What Is An ADU?

Definition of ADU (Accessory Dwelling Unit)

Although they are called by many names depending on where you live, an ADU, which stands for Accessory Dwelling Unit, is a second home that is located on the same property as a primary residence. More and more cities are now allowing ADUs to go with main houses thus providing more housing in our neighborhoods without creating more sprawl. Primarily ADUs are located on residential properties that are zoned for single family housing, although the can also include living spaces in basement apartments or additional units on some multi-family properties.

Accessory Dwelling Units can take many forms as we will discuss below, but they need a few basic elements to be considered a full dwelling. Each ADU must have a kitchen, bathroom, living space, and sleeping space to be considered an ADU. They are full stand-alone dwellings that can provide everything someone would need to live in the unit long term. Basically they are smaller houses, typically limited in size and height by local zoning regulations.

View of a backyard detached ADU we designed on Bainbridge Island, Washington. Detached ADUs are the best option for rental units or for aging-in-place.

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Types of ADUs

There are a range of options for creating ADUs on a particular property. These include building a detached ADU as a stand-alone structure, our preferred option. You can also build an accessory dwelling unit as an addition to your existing house, sharing a wall. Renovating a basement into an ADU is common, as-is converting an existing garage into a living unit. I have seen a few attics converted into ADUs, although creating a separate entrance can be challenging. I have even worked on a couple of projects to carve out parts of a client’s main house into an ADU, dividing it into two dwelling units under one roof. I have also designed ADUs over garages which is a very common request, especially in urban locations where off-street parking is desirable.

Although there are many options, and there may be a specific type that best suits your property, by far the easiest type of ADU to build is a new construction fully detached ADU. There are a bunch of advantages to keeping the new unit separate from the main house. First, from the perspective of someone living in each unit, having a fully separate dwelling is a nicer experience from a noise and privacy standpoint. There are no shared walls or floors, sound insulation isn’t much of an issue, utilities can be completely separate, and with careful design consideration, each unit can have some private outdoor space to enjoy.

There are also some technical reasons I recommend detached ADUs. Working within the confines of an existing structure can be difficult - especially if you have an older home or aging garage. Building new living units requires that it meets current codes and regulations. When building within an older house, cities often use the new project as an opportunity to make people upgrade the existing home to meet current codes as well. This could mean doing structural upgrades, replacing stairs that don’t meet code, adding egress windows, putting in fire and sound separation, and sometimes even adding residential sprinkler systems to the house. These can be complicated upgrades that add significant cost to the project. Plus, doing a detached ADU give you the most flexibility with the design, to make a space that is both great to live but also meets your style and aesthetic choices.

Examples of ADUs

Discussing the types of ADUs that can be built is one thing. Seeing examples of what these spaces can look and feel like is something else. Below are a range of projects that showcase the various types of accessory dwelling units that are possible. All are designs that I worked on and styles that vary based on the location, the client’s needs, and surrounding context.

Detached ADU

ADU over garage

Attached ADU

Basement ADU

Detached ADU

Internal ADU (carve-out)

Attached ADU (connected with a breezeway)

Internal ADU

Detached ADU

Other common names for ADUs

Although ADUs, or accessory dwelling units, are the technical term used to describe these project types, there are many other common names to describe these housing types and the common use of these names vary depending on location.

Backyard cottages, granny flats, laneway houses, casitas, and guest houses are all common terms used for the stand-alone detached ADUs. For garage conversions or apartments built over garages you may hear them called carriage houses or garage apartments. These have been featured in pop-culture, specifically the Fonz lived in an ADU over a garage in Happy Days, and one of the main characters in the Hulu show The Handmaid’s Tale also lived in an apartment over the garage. In the show Full House the family had both a basement ADU and an Attic ADU.

Attached ADUs have been called bump-out ADUs in some places although this isn’t the most common ADU type. On the other hand, basement ADUs are some of the most common ADU projects and have many common names including: basement apartments, au pair units, mother-in-law units, in law units, Pied-à-terre, secondary suites, accessory apartments, to name a handful.

Regardless of what they are called we believe adding an ADU is a great idea and a worthwhile investment. They provide housing, can increase your property value, and can also generate rental income. You could also consider building yourself an ADU to live in while renting out the primary residence to a young family. Or perhaps you want to having aging family members live close by to save on the cost of care or to have grandparents nearby to help with childcare. Regardless of the reason for building an ADU, we think they are great projects that are fun design challenges.

One thing of note, ADUs are not tiny houses. Tiny houses are their own category of dwelling and typically refer to very very small units built on wheels. Unlike tiny houses, Accessory Dwelling Units are built on real foundations and are permanently fixed to their location just like a full sized house.

Typical Uses For ADUs

There are many reasons people consider for adding an ADU. Sometimes it is for increased living area for their family. Often it is to provide housing for an aging family member so they can be close by if they need care. Perhaps the most common reason to build an ADU is as a real estate investment, to generate rental income and increase property values. Building an ADU can be a great investment regardless of the use. As a property owner, you get to leverage an asset you already own - land - to add a new home. This is a low-barrier to entry into small scale real estate development. Accessory Dwelling Units also can be designated as affordable housing. Many cities, like Portland, Oregon, are actually incentivizing people to make ADUs affordable by waiving some of the development fees and also allowing property owners to build additional units if a percentage are designated as affordable. Even without the incentives and designations, adding an ADU creates naturally affordable housing since there are less costs to build an ADU than a new house considering the land is already owned and the size is limited.

We also sell Modern ADU Plans in order to help make these more affordable to a wider range of people.

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Custom Homes: How Much Do They Cost?

If you are considering designing and building a custom home there are three steps you need to take as you embark on this journey. You have to find land, find a designer and builder, and set a project budget. When people reach out to us about their projects, cost considerations are typically the first question they ask. They may already have land picked out, or are looking for our help as they consider different properties. What they are most stressed about is seeing if they can afford a project that meets their goals and ideas. Budget is top of mind and usually a big part of our early conversations. Here we will discuss the various aspects of a project budget and some numbers of recent projects so you can have a jumping off point as you consider your project.

When I read articles like this, I always get frustrated trying to find the answer to the first question. How much will it cost? Rather than make you scroll all the way to the bottom (although you should definitely read through everything) let’s get right to the chase. The answer is $1,260,000 plus the cost of land.

Of course that isn’t exactly accurate. It is impossible to give you an exact number without knowing more about the specifics of your project, but it it isn’t that far fetched. I would say that most nicely designed custom homes will start at around $1 million and go up from there. It may be possible to build something very nice for under that amount, especially if you are looking for a smaller project like a weekend getaway cabin, or some other modest project. But for most full sized houses, say 1,500 square feet and up, I would venture to guess that the final cost will start at around $1 million when all factors are considered. Keep reading for a more detailed breakdown of how these costs add up.

There are three main expenses you will need to plan for with a custom home. The first is the cost of the land. Second is the soft costs - all the fees that are needed to develop the design and get permission to build the project. Third are the hard costs - the expenses of actually building the project.

Land Costs

Unfortunately you are going to hear this a lot, but this cost is widely variable. Depending on the location, the local market, the type of land, the quality of the property, surrounding property values, views, water features, and other qualities, the price can fluctuate. For example, I’ve been looking at land in the Hudson Valley and Catskills regions of New York State and have seen land that cost $2,000/acre and others that have been over $100,000/acre. The main factors were views, if the property was on a river or lake, and the location - closer to New York City or the trendy towns in the Hudson Valley drove up the cost significantly. I am hoping to narrow in on some properties in the range of $10,000 per acre and want a minimum of 10 acres of land. So my land budget is about $100,000 to $150,000.

On the other hand, I have also been helping a client search for land in the High Desert of Oregon (a couple hours drive from Portland) and we are eyeing a property that is 60 acres for $199,000, or around $3,300/acre.

Soft Costs

When just throwing around rough numbers as you start thinking through the project budget, we recommend you allocate 20% of the project budget to soft costs with the remaining 80% going to the hard costs. This is a general rule of thumb and a good guideline to use before you start getting actual numbers to plug into your calculations. This 20% would cover design fees, engineering costs, permitting fees, insurance, financing costs, site survey, and other required expenses before ground is broken to start construction. Let’s break this down a bit further.

Design Fees
You can budget about 10-15% of the project budget for design fees. Some designers might be a bit cheaper but also may not offer the same level of service. Designing a custom home is a significant investment and you want a design team that is going to give it the time and dedication it needs to do it right and create a high-quality result. Compared to the cost of construction, design fees are still a small percentage of the overall project and not somewhere you want to cut costs. Design fees vary depending on the firm, their reputation, the budget of the project, what scope of work is included in the fee, and the local market, among other factors. In NYC we have seen 12% as a very common design fee percentage, where famous starchitect firms may be 15% or some could even be as high as 20-25%. I offer a few different tiers of design fees depending on the scope of work, 10%, 12%, or 15%.

For argument’s sake, let’s say you are looking to spend $1,000,000 on the construction of your home. You can thus budget between $100,000 to $150,000 for design fees.

Engineering/Consultant Fees
A few different engineers are needed for most residential projects: civil engineering, geotechnical (soils) engineering, and structural engineering. Occasionally we may also engage a Mechanical, Electrical, Plumbing engineer if it is a complex project, although typically we approach these systems as a design-build where the contractor who installs the system also does the design and permitting work. You can budget about 1% of the construction cost for each engineer as a placeholder before we get actual bids from companies. Fees could vary if it is a complicated site; steep topography for instance. A site survey is also required and could add another $5,000 or so in fees depending on the site. Other consultants may also be necessary like arborists, landscape designers, energy consultants, and others depending on the specifics of your project and your property.

For that same theoretical $1,000,000 project you are looking at around $35,000 to $50,000 in consultant fees.

Permitting Fees
Each jurisdiction has their own permitting process and associated fees. Typically there is a permit review fee for the actual time and effort for the building department to review the drawing set and issue an approved permit. On top of that, most cities and towns also asses system development charges for new construction. These are fees that cover town expenses for infrastructure and services like roads, schools, utilities (water and sewer systems), parks, and other amenities.

On a custom home we completed in Portland that was valued at $750,000 in new construction, the total city fees came in around $47,000.00. That includes about $16,500 in permit fees and $30,500 in System Development Charges (SDCs). That is a lot of money! Not every jurisdiction will be this expensive to get a permit. Call the town where you are planning to build and talk to someone in their building department. Alternatively, many places have permit fee calculators on their building department websites.

Let’s use $50,000 to be conservative.

Insurance
It is recommended that you carry insurance during the construction process. This would cover things like unexpected events: think fire, weather, vandalism, or theft. The goal is to have security that if there is an issue during construction your insurance would cover losses or increased expenses to prevent the bank from foreclosing on the project. Policies vary depending on deductible and coverage amount. Annual premiums can range between 1% and 4% of the project cost but call an insurance company to get specific quotes.

Say 1% for now, for $10,000.

Financing Costs
This would be the cost of securing a construction loan, plus the interest you will pay throughout the project’s construction. Most construction loans work like a line of credit, so you make monthly draws to pay for the General Contractor’s labor and materials. You then start accruing interest on that balance until the project is complete and you then refinance into a more traditional mortgage (at a lower interest rate and a longer loan term). Closing costs on the loan could be around 1% of the loan amount, and interest can add up quickly - probably around 5% of the loan amount over the course of year, although the actual amount will depend on the interest rate and length of construction.

Say $50,000 for the loan fees and 12 months of interest accrual.

Altogether we are right around $260,000 in expenses (using 10% for design fees) on top of the estimated construction cost of $1,000,000. That is almost exactly 20% of the project cost ($260,000/$1,260,000).

Hard Cost

Before construction has even begun you have already spent about 20% of your project budget, more if you include the cost of land. We understand it is stressful being this far into the project without even seeing progress on the site. This is why everyone is so excited when that permit approval arrives and construction can begin.

At this point the cost of your project shifts from the design team to the General Contractor. The GC will take over leading the project and will typically invoice monthly based on the construction progress and the month’s labor and material costs accrued. This monthly invoice will be approved and then sent to the bank to issue payment from your construction loan.

Let’s discuss how we can estimate the cost of construction. First, I’d like to state for the record that I dislike cost per square foot calculations. All square footage isn’t considered equal, so we shouldn’t assign the same cost evenly across the project. Kitchens and bathrooms are expensive with all of the electrical work, plumbing work, casework, cabinets, counters, tile, etc. On the other hand, bedrooms, typically just empty rooms, are cheap square footage. So adding a second kitchen is much more expensive on a cost per square foot basis than adding an extra bedroom. This all being said, sometimes cost per square foot is the easiest way to make quick calculations. Let’s walk through some calcs.

Typical construction costs for a nice custom home start at around $350 per square foot and go up from there. For example, a new construction 2,500 square foot home would have a rough construction budget of $875,000 (2500 x $350). However, if you are looking for something more towards the luxury side, you could start seeing cost per square foot approach $500/sf or even higher. There are hundreds of decisions we will make together throughout the design phase that will affect this cost. In our $1 million dollar house example mentioned in the soft costs section, we would be looking at about $400/sf.

Why do I hate cost per square foot so much? Let’s say you want a smaller house - more of a weekend getaway in the mountains rather than a larger home for full-time living. In that case maybe you only need a nicely designed 1,200sf home. Using the cost per square foot calculation you will get a construction cost of $420,000. Sounds great. However, that is misleading. The expensive parts of the home (kitchens and bathrooms, excavation, and utilities, etc. ) aren’t being subsidized by as much cheap square footage (bedrooms, dining room, etc.). You should expect the cost per square foot for smaller projects to be higher than larger homes. For some of the Accessory Dwelling Units (ADUs) we have designed, cost per square foot often came in at around $500/sf or more, and we even saw a couple come in closer to $800/sf (one was on a steeply sloped site with complicated foundations and structural requirements).

For nice round numbers, from my experience I would say a high-quality ADU would start at $250,000 in construction cost or $300,000 in full project costs and up. A small vacation home would start at around $500,000 in construction cost or $600,000 in full project cost and up. Meanwhile, a full custom home would start at around $1,000,000 in construction cost and $1,200,000 in full project cost and go up from there.

Other considerations for Construction Cost:

Clients have immense control over the final cost of their projects. We guide you through the hundreds of decisions to be made but at the end of the day you are the one who has the final say on what you are willing to spend, and make the decisions that affect the cost. For example, you can get tile for the bathroom that cost $3/sf or tile that costs $30/sf. Kitchen appliances could be a few thousand or $30,000. Windows and doors can be cheap vinyl or luxury triple-pane, high-efficient, European tilt-turn windows for hundreds of thousands. Roofing, siding, flooring, structure, heating/cooling systems, hardware, lighting fixtures, and dozens of other decisions will have large impacts on the final cost.

Of course the property you pick at the beginning will also impact the construction cost. Steep slopes could necessitate more expensive structure, retaining walls, and other site expenses. Granite bedrock close to the surface can make excavation extremely expensive, especially if you are considering a basement. Having to clear trees, or level a flat part of the site can add costs. If the building site is far back from the street you could have to build a long driveway and pay to get utilities back to the house location. If the property is rural and necessitates a septic system or water well, rather than tying into the city utilities, that could add significant cost. These are all reasons it is important to do due diligence and maybe even hire the design team prior to putting in an offer on a piece of land.

Conclusion

There is a lot to think about. Budgeting needs to be well thought out and will be affected by lots of outside forces and personal decisions. These numbers are just rough guidelines to get you started as you consider your options. Most importantly, we are happy to talk with you about your goals and ideas and offer any advice or insight based on the specifics of your project. Don’t hesitate to reach out with any questions. We can also help you crunch some early numbers and even help you find land if you want some help looking for the right property for your dream home. Let us know how we can help.

The Hill House is a schematic design we developed for a client in southern Washington State. The estimated construction cost was around $500/sf for a total cost of around $2,000,000. Excavating on a sloped site to get a basement garage, concrete and steel construction system, and the floor to ceiling window package were significant drivers of this cost.

The Sheltered Nook House was a very cost effective project coming in at around $350/sf for the house itself. At 2,200 sf the cost was around $780,000 for the house structure. On top of that was the cost of the land, cost of installing a well and septic system, some site grading, some excavation and retaining walls. The total project was closer to $1,000,000 when considering those other costs.

This Accessory Dwelling unit is just 700sf and ended up at around $400/sf. Smaller projects have a much higher cost per square foot since they have all the expensive parts of a full house but without the cheap space (extra bedrooms, living and dining rooms, etc.).

This project is around 1,200sf with a project cost of about $360,000 for a cost per square foot of around $300/sf. This is one of the more affordable projects we have done with the goal of balancing nicely designed spaces with affordable materials. Fiberglass windows and doors, hardie-siding, asphalt shingle roof, Ikea kitchen, and affordable tiles and floor materials kept the cost down. Plus the 1,200sf includes the garage area which is a simple empty room with concrete floor and drywall walls.

Design Inspiration: 4 Historically Significant Custom Homes

These projects are pillars of residential design in America - projects that are studied in architecture school and still resonate with custom home designers today. Innovative at the time, they have stood the test of time and still reflect a lot of the values people look for in their homes today. Each has a relationship to the land, takes advantage of views, and are experimental with materials and structure.

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Stahl House (Case Study House No. 22) - Pierre Koenig

Where the homes I feature below are more about a connection to nature and landscape, this incredible house is all about the city. That view demanded that the architecture be open, transparent, and light on its feet. The modern aesthetic and steel structure are perfect responses to this context, giving the home a lightness that appears to float out over the city lights below. That view will never get old and the architecture is perfectly crafted to respect the drama of the site and recede into the background.

Book: The Stahl House: Case Study House #22: The Making of a Modernist Icon

Fallingwater - Frank Lloyd Wright

I was lucky enough to visit this house back in 2006 while driving cross country to attend graduate school where I earned my Master’s of Architecture degree from the University of Oregon. I snapped the photos below on an old digital camera so please excuse the resolution and focus. I’m not sure there is a more recognized house in the world, or one that sits in a more incredible setting. Despite seeing hundreds of photos over the years, visiting Fallingwater in person was a transcendent experience. Feeling the spaces, experiencing how the home is woven into the landscape, seeing how the interior flows outdoors, demonstrates just how spectacular this design really is. These images don’t do it justice. Go visit this house in person. It will exceed your expectations.

Book: Fallingwater

Farnsworth House - Mies Van Der Rohe

A house distilled down to the bare minimum, this design elegantly sits in the landscape while the interior is wrapped with views out over the surroundings. WIth the simple structure, slight elevation from the land, and an ultra simple form, the architect used minimalist design to compliment the beauty of nature. The interior is all about the 360 degree views out with the floor to ceiling glass walls the wrap the entire home. The spaces within are divided by the service core, meaning there are practically no walls that impeded the views of the outdoors. This may be one of the most influential houses in American architecture and reflects many of the values that I strive for in my work: touch the ground lightly, emphasize the indoor-outdoor connections, keep the form simple, use a minimal material palette.

Book: Broken Glass: Mies van der Rohe, Edith Farnsworth, and the Fight Over a Modernist Masterpiece

Eames House (Case Study House No. 8) - Charles and Ray Eames

The proportions, materials, prefab elements, and color composition of the exterior is what you first notice about this house. Yet more importantly is how the house sits on the site. Nestled into the hillside the house is protected on one side, while the double height facade on the other, opens up to a meadow and a grove of eucalyptus trees on the other. It is this relation to the land that makes this house what it is. Too often modern architecture is thought of imposing it’s rigid form on the surroundings. Yet the truly great homes strike a balance between their form and structure and responding to the specifics of their site. It is this sensitivity, that Charles and Ray Eames displayed in this project, that I’m inspired by.

Book: The World of Charles and Ray Eames

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These are some of the most famous houses in America, inspiring countless architects and designers over the decades. They celebrated new materials and construction technology. Their style was a stark departure from the more ornamental aesthetics of earlier home design. Yet, what makes me fall in love with them is how they each celebrate the natural surroundings despite their distinctly industrial material palette and structural systems. This juxtaposition both celebrates how they were built while still paying deep respect to the landscape. This combination, designing for the specific strengths of each material while crafting a response to the specifics of the land, is what I love about residential design. Working with clients that share these values, exploring each site, and working through design iterations to reveal the ideal solution is what makes design so much fun.

What You Need To Know Before Building A Custom Home

Building a custom home can be an exciting and rewarding experience, but it's important to be well-prepared before starting the process. These projects can be more complicated and stressful then they appear so it is also advised to hire an experienced design team to help guide you through the process. Here are a few things you should know before building a custom home:

1. Set a custom home budget.

   Building a custom home is a significant expense, so it's important to set a budget that you are comfortable investing in the project. More importantly, it is important to be transparent and share your accurate budget numbers with your designer and general contractor. Transparency and trust will make the project more successful, so be open with discussing what you are comfortable spending with your design team. As you are calculating your custom home budget, be sure to factor in all of the costs associated with building a home, including the cost of land, materials, labor, permit fees, design fees, and any additional features or amenities that you want to include. You should also be prepared for unexpected costs that may arise during the construction process, so building in a contingency amount is recommended.

2. Choose the right location for your custom home.

   The location of your custom home will be a key factor in its value and appeal. Consider factors such as proximity to schools, public transportation, and amenities like shopping and dining. You should also consider the long-term prospects for the area, including the potential for future development or growth. You want your investment to pay off, and in general, real estate tends to appreciate in value over time. Location can also impact other aspects of your project like, availability of material and labor, cost of mobilizing a construction site, complications with foundations and structure. Engage your design team to talk through to the pros and cons of your property and the ideal location to place your project on the site.

3. Work with a reputable and experienced residential builder.

   Building a custom home is a significant investment, so it's important to choose a reputable builder with a proven track record of delivering high-quality homes on time and on budget. Research and compare builders in your area, and make sure to get references and check their credentials before making a decision. We also advise picking the builder based on reputations, skill, and alignment of values. Don’t select a contractor based on price as often the cheapest builders will end up cutting corners. Pick a contractor and then work with them and your design team to develop a design that meets your budget.

4. Choose the right design team with custom home experience.

   A good design team can help you turn your dream home into a reality. Look for a team that has experience in custom home design and a track record of creating functional and visually appealing homes that align with your taste and values. You should also consider your personal style and preferences when choosing a design team, as they will be working closely with you to bring your vision to life. A great designer is worth the investment and a well designed home will be worth more in the long run. This isn’t a place to cut corners or tighten your purse strings. Investing more in the design phases can save you thousands of dollars in construction, and can lead to a home that is much more enjoyable for you and your family and much more valuable as an investment.

5. Plan for the future with your custom home design.

   While it's important to focus on the present when building a custom home, it's also a good idea to consider the future. Consider factors such as the potential for future family growth or changes in your lifestyle, and design your home with these changes in mind. This can help ensure that your custom home will meet your needs for years to come.

Overall, building a custom home is a significant investment that requires careful planning and preparation. It is recommended that you assemble a talented team to help you achieve your goals. A talented designer, trustworthy builder, a great location, a carefully crafted budget, and a long term plan can take the stress out of the process and help ensure your new home project is a resounding success.

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Interested in starting a custom home project with us? Tell us about your goals and ideas using the form below:

Design Inspiration: 4 More Custom Homes We Love

In our first design inspiration post we discussed how we are inspired by the creative work of others and use precedent studies to influence our own design practice. We are returning to this theme to share four new projects and firms that we admire and have impacted our approach to residential design. These reinforce our love for homes that are woven into the landscape. We also included a couple of smaller scale projects that are more modest than the sprawling luxury homes in our first post. Great design is needed at all scales and all budgets.

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Lake Flato - Aegean Pool House

This project is a small guest house and pool house but reflects many of our design values. The celebration of structure is prevalent as the architects highlighted the columns and beams that support the roof. The stone chimney and concrete walls ground the project, while natural wood finishes make the interior spaces feel warm and inviting. Each room opens to the outdoors allowing life to flow from the interior out into the landscape. Large roof overhangs create outdoor rooms that encourage life and activity to take place outside. Meanwhile the simple modern form and shed roof let the materials and details be the center of attention. This is a superb little project.

Rick Joy - Tucson Mountain House

Rammed earth is one of our favorite materials and we can’t wait until we have a client that lets us explore designing with it. The thickness of the massive walls exude a feeling of being grounded and protected. The texture and color of the earth give the walls intimate scale and celebrate the unique qualities of ground from which they are made. Juxtaposing this heavy weighted material, large window walls and openings allow the interiors to remain open to the landscape and be illuminated by natural light. Once again, the materials take center stage while the form is relatively simple and subdued. The main move is the butterfly roof which gives the home a dynamic feel while responding to the mountain peaks and valleys surrounding the site.

Nature Humaine - Poisson Blanc

This humble cabin fits perfectly into the snowy landscape of Quebec. Unlike the past two projects, the materials recede into the background while the large windows allow the exterior to the be focal point. With such a modest footprint, the design is pared down to the basic necessities with bedrooms tucked below the vaulted living spaces above. This organization of spaces responds to the sloped site and gives the primary living spaces better views out into the forest. Inside, the single wood casework wall defines the space and creates a warm counterpoint to the white interior. I would love to spend a weekend here with friends and a great book or two.

MW Works - Whidbey Farm

One of my favorite houses, I love how this home meanders through the forest, with the architecture seemingly placed to avoid the majestic trees. Again, the natural materials on the interior and exterior compliment the surroundings with the simple material palette of stone walls, natural wood, and black accents. This home does a great job at making the exterior become part of the interior life, with window walls, and corner glass that open each room to the outdoors. The kitchen and bedroom in particular are beautiful spaces that show the power of borrowed vies. The large overhangs further encourage outdoor living and connecting the home to the landscape.

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Once again we are drawn to homes that are interwoven with the surrounding landscape. Indoor spaces that flow outdoors and blur the boundaries between indoors and outdoors reflect how we want to live. Being connected to nature makes life more enjoyable as we can experience the changing of seasons or even the shifts of weather throughout a day. Each of these projects reflect these values and do an excellent job of creating clean modern homes that feel rooted in the specifics of place.

If these projects inspire you and reflect your values, please reach out to us. We would love to collaborate on crafting a design for your custom home that reflects your lifestyle and is seamlessly integrated into the specifics of the land. Homes that compliment nature and inspire a more connected life.

ADU Design Process

In order to deliver great services to our ADU clients we have developed a design process that we use to direct each project. This process has been refined over the past 10 years designing over 60 ADU projects across Washington, Oregon, and California. We want you to know what to expect when you choose to work with us and to know that by going through our design phases you can have confidence that we will arrive at a great design solution to your problem. Plus, designing can be fun. Once you know what to expect, you can relax and enjoy the process of design and participate in the creative energy of crafting a beautiful ADU.

The Five Phases of Every Project

Design is a process of discovery, where you share your goals and ideas, we learn about your needs and your lifestyle, and together we craft a layout and design that balances all the influences into an ideal solution. If you think of it like cooking, first we need to identify and gather all of the ingredients. We then need to cut, chop, blend, and measure them to make sure they are in the right mix. We then spice them and cook them together. Finally we plate the dish, and serve it. Five steps are needed to refine everything that goes into a project. We break them down into the following phases:

Pre-design - PD

The pre-design phase is when we conduct the research needed to lay the foundation for the future design work. This includes zoning and code research at the city offices, a thorough analysis of your property, coordinating a survey of your property, and meeting with you to create the program for the project.

A program is a spreadsheet of all the spaces desired for the ADU as well as any other features or items that need to be considered in the design. We want to identify all of the rooms, rough sizes, notes on any adjacencies that are preferred, ideas on how interior spaces connect with the outdoors, and any other goals for the project. For example, a recent c;ient we worked with was building an ADU for their aging mother to move into. Although ADUs are a small home it was important that we designed space in the living room to fit her baby grand piano. It is vital to get information or requests like this documented up front so we can meet your expectations. As we develop the floor plans and layout of your project we want to make sure the design work takes your ideas and specific needs into account.

Deliverables:
Measured Site Plan
Programming Document
Surveyor has been hired

Schematic Design - SD

With the research complete, understanding the specifics of your property, and the programming document in hand, we begin designing your project. We typically start with exploring floor plans, and developing a site plan to talk through how the ADU will sit on your property, and how the interior spaces will be organized. We typically present a few options and have a working meeting where we talk through the pros and cons of each option and sketch together to narrow in on a preferred choice.

After this first SD meeting, we refine the site plan and floor plans based on your feedback so it’s the right solution for you and your property. We have a second meeting to go over the refined floor plans and begin talking about the 3D views of the project and define the overall look and feel. This includes talking about elevations of each side of the ADU and sections through the spaces to show vertical relationships. In the meeting we will discuss the functionality, flow, style, and other aspects of the project that could affect the details and costs. This will be another working meeting where we will sketch together to refine our design ideas to best address your taste, needs, and budget.

Deliverables:
Schematic site plan, floor plans, building elevations, building section
3D views as needed to describe the design intent

Construction Documents - CD

With the overall form, layout, look and feel of your project now defined, we begin the process of documenting the design to get it ready for both permitting and construction. We will gather and/or create all the documents needed to acquire permits and get an accurate bid from a general contractor (GC). We’ll also coordinate the necessary engineers and other consultants and combine their work with ours. This is the phase where we finalize all of the details like finishes, fixtures, and equipment to match your preferences and budget.

During this phase, your designer will create a dimensioned site plan, demolition plans, floor plans, cross-sections, elevations, construction details, and finish schedules. They will also coordinate with any sub-consultants needed to complete the work like structural engineers or other experts. At the conclusion of the drawings your contractor will provide an updated construction bid based on the final construction documents.

Deliverables:
Dimensioned site plan, floor plans, reflected ceiling plan, building elevations, building sections, interior elevations, enlarged floor plans, assemblies and construction details.
Door, window, and finish schedules
Finishes, Fixtures, and Equipment

Permitting

At this point the design and documentation work is complete. Before we can break ground and start construction we need to get permission by the local building department. Unfortunately, each town, city, county, or state, has their own rules and regulations when it comes to permitting a new building, even small ones like ADUs. During this phase we will work with the local officials to fill out all of the paperwork and supply all of the drawings and other information needed for them to review the design and ultimately approve the project. Typically this includes a few rounds of questions and revisions requested by the reviewers as they compare the designs against all of the local laws. We will work with them to make sure they have everything they need and your project gets reviewed and approved in a timely manner.

It is important to note that each jurisdiction has their own rules and their own process. It is very difficult to predict exactly what they will request or what the timeline will be for the review process. We do our best to research the local requirements and plan accordingly but the actual review process is out of our control. There are also some additional reviews that could be required that can add time or fees. For instance, projects in historic districts require special review, which may mean more time and additional fees. We will identify this during our Pre-design research and inform you of any special circumstances that we will have to plan for.

Deliverables:
Approved building permit
Construction Drawing Set

Construction Administration - CA

During the construction phase we communicate with you and the contractor to answer questions or provide additional information to help realize the design intent. We check quality by periodically visiting the site to observe progress. We also are available as a resource to answer any questions the GC has or to clarify anything on the drawings. We can also help work through any challenges and review and approve any requested changes the GC proposes. Construction includes many steps and a lot of communication, and we are with you along the way in order to help facilitate a high quality finished project. We are you trusted advisors and advocates to make sure that the end result is in alignment with your values and expectations.

Deliverables:
Designer involvement throughout construction
Periodic site visits to observe construction progress

Project Closeout

Now that construction is complete there are a few final tasks to closeout your project. First, we want to celebrate the success of the project. We sponsor a small gathering at your ADU to acknowledge all of the hard work the entire project team has put into the effort. We invite the entire design team, clients, consultants, and contractors to gather and celebrate the achievement. We provide the refreshments if you are kind enough to offer the ADU space.

Finally, we schedule a professional photographer to come out and document the completed project. We want nice photos to use in our portfolio and marketing materials so we can show future clients the work we have done. We also want you to have copies of these to show your beautiful ADU to friends and family.

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Additional Services

Although we find the process above can serve most ADU clients and deliver a great result, there are always situations that are unique or clients who have particular requests outside our standard scope of work. We offer a range of additional services that can be added depending on your needs and the specifics of your project.

• Renderings

• Physical model building

• Additional design options

• Landscape design

• Historic Design Review

• Sourcing materials

• Furniture selection

• Certifications (LEED, Passive House, Net Zero, Earth Advantage, etc.)

These are a few of the services that have been requested, although if there is some way we can add additional value to your project that isn’t included here, please reach out to us and lets talk through how we can help.

The interior of the Stilts ADU in Portland, Oregon, used reclaimed doug fir for the flooring, ceiling, trim, and counters, creating a unified, warm and inviting interior.

Definitions

Programming: programming involves research and decision making that helps the designer and owner establish the requirements and design criteria for the project. Programming can range broadly from identifying the project’s goals and objectives to particular elements, such as the precise size and characteristics of a space. It is an essential first step before the design phase and a critical communication tool throughout the project. A program guides participants from concept to construction documentation.

Survey: Site surveys are inspections of an area where work is proposed, to gather information for future design work. It typically determines the property lines, topography, location of existing structures and site features.

Section: A section drawing, or simply a section, shows a view of the design as if it was sliced vertically. Where a plan is a drawing looking down at the layout of a home, a section is a vertical drawing that shows the relationship of spaces vertically. We typically use these drawings to show ceiling heights, lofts, stairs, relationships between first and second levels, and other vertical design features.

Reflected Ceiling Plan: Where a plan shows what is happening on the floor, a reflected ceiling plan, or RCP for short, shows where the design elements on the ceiling would correspond to the floor plan. It is reflected because rather than looking up at the ceiling, the view is actually looking down at the floor but reflecting what is happening on the ceiling above.

Finishes: This is simple a fancy word for materials. Finishes are all the things we need to select during the design process like flooring, cabinet fronts, countertops, tile, siding, roofing, etc. We want to select and document all of the materials that will be attached to the building in order to get accurate cost estimates.

Fixtures: These are the all the accessories that are attached to the building - things like faucets, showerheads, lighting. fans, switches, outlets, smoke detectors, and others.

Assemblies: This is a drawing that show all of the layers and materials that make up a floor, wall, or roof. It is a detail drawing that is used to inform the contractor how to build, or assemble, those items.

Schedules: Typically we use schedules for all of the doors, windows, and rooms in a project to create a spreadsheet that adds additional information that can’t fit on the drawings themselves. For instance in a window schedule we will list every window in the project and describe the manufacturer, model, size, height, materials, color, operability, and other information. In a room finish schedule we list out all of the rooms in a project and then describe the materials that will go on each wall, floor, and ceiling.

Why New York State Should Legalize ADUs

New York State is considering The Accessory Homes Act

I am excited to see that there is proposed legislation in New York State - The Accessory Homes Act - aiming to legalize ADUs statewide. Coming from Portland which has been at the forefront of the ADU trend, and Oregon which recently passed legislation to also legalize accessory dwelling units statewide, it is great to see that this housing type is spreading across the country. This is great news for New Yorkers.

This legislation is a huge win for the state of New York including homeowners, renters, affordable housing advocates, and landlords alike. It is rare to see legislation that will benefit such a wide spectrum of groups and businesses. And it is encouraging to see that elected leaders are looking for new ways to address housing issues facing our cities and towns by allowing for the addition of new housing typologies.

The Accessory Homes Act (S4547, A4854) would direct local governments to legalize accessory dwelling units (ADUs) in all areas that are zoned for residential use, thereby providing extra income for homeowners, new affordable housing, reasonable protections for tenants, and new tax revenue for local governments. The bill is backed by a diverse coalition of housing nonprofits, tenant activists, policy organizations, fair housing and immigrant justice organizations, and more

I’m particularly glad to see that part of this legislation calls for the state to make the permitting and approval process for these projects streamlined, reasonable, and affordable. This will go a long way in encouraging people to add accessory dwelling units to their properties across New York State.

Thank you to New York State Assemblymember Harvey Epstein and New York State Senator Pete Harckham for introducing this important legislation.

You can read the full bill here:
https://www.nysenate.gov/legislation/bills/2021/A4854

You can send a letter in support of the bill using this link:
https://actionnetwork.org/letters/tell-albany-to-legalize-accessory-dwelling-units?source=direct_link&

Benefits of ADUs:

• ADUs increase housing options both for renters, multi-generational living, and for those looking to downsize.

• ADUs are relatively affordable to build because there is no cost to the land.

• ADUs can provide rental income to families - helping them pay off mortgages or debt, have additional spending money, save for putting children through college, or plan for retirement.

• ADUs are inherently sustainable developments - they double down on existing infrastructure rather than requiring cities to invest in expanding utilities and roads. Being small, they also have lower demand for energy and water use.

• ADUs provide cities and towns with new residents and an increased tax base.

• ADUs can be beautiful - great design can make these highly desirable places to live.

• ADUs increase property values for homeowners.

I believe when this legislation passes it will be great for New York State and I’m glad elected officials are working to allow these projects statewide. Although some may be concerned about this change and how it will affect the character of their neighborhoods, I reassure you that change is good as it shows we are making progress towards addressing some of the issues related to housing and affordability. WIth the nature of ADUs being smaller homes located on existing property, they have a minimal impact on the surrounding neighborhood other than introducing new neighbors and new customers for local businesses. I have experienced firsthand how ADUs, granny flats, or guest suites, have grown in popularity across Portland and become a highly desirable addition to properties. They have been supported by politicians, homeowner groups, housing developers, affordable housing advocates, and community groups. Each year the demand for these projects increase as people realize all of the benefits they provide. And each year more people advocate for more of these projects to be allowed as they see the benefits they bring to a neighborhood.

ADU Design Services

I have worked with clients on the design of over 60 ADU projects to date. Most of these are in the greater Portland, OR area but I’ve also worked on a projects in Seattle, and the Bay Area. Having returned to New York about a year ago I’m looking forward to advocating for these project types across the state, and working with people to add ADUs to their properties. There are a range of reasons ADUs benefit homeowners and renters alike. I have worked on accessory dwelling units aimed at aging-in-place and barrier free living. Others were targeting Airbnb or short term rentals to generate additional income. Some clients were looking to downsize and move into the ADU once their children moved out, or building granny flats for aging family members who needed additional care. Regardless of the use, ADUs are great assets for homeowners and renters alike. I even sell plans of pre-designed ADUs for those who would like to save some time and money compared to going with a fully customized design.

If you have any questions about ADUs, want to learn more about the cost of designing and building these project types, or would like to discuss design ideas for a specific project, please get in touch. I love answering questions and sharing my expertise in this wonderful project type. I’m also taking on new clients if you are looking for a designer.

The exterior design of the ADU is a contemporary twist on a traditional house form. The simple gable roof reflects the form of the primary dwelling while the cedar screen and trellis provides privacy, defines an outdoor patio, and shades the western sun.

The interior of this ADU is bright and open with a combined kitchen, livingroom, and dining area. The vaulted ceiling and large windows make the smaller dwelling feel spacious and introduces lots of natural light and views to the garden.

Purchase pre-designed ADU Plans here:
https://lucasgraydesign.com/adu-plans

Frequently Asked Questions about ADUs

Question 1: What is an ADU?

ADU is an acronym that stands for Accessory Dwelling Unit. The term refers to adding secondary homes on a property that already has a primary residential unit. For instance, if you own a single family house and build a second, smaller home in the backyard to rent out, that would be considered an ADU. This second unit could come in many forms including detached new construction ADUs, garage conversion ADUs, attached ADUs, basement conversion ADUs, or other internal ADUs. We find that the most common and ideal option for most properties is to do a detached accessory dwelling unit as they are the least disruptive to those living in the primary house.

Different places have different names for ADUs so you may have heard some of these names: granny flats, in-law units, backyard cottages, guest suites, laneway suites, au pair suite, basement apartment, secondary units,and more.

Regardless of what we call them, ADUs are great ways to add new housing options to our neighborhoods. They are used for a variety of reasons and are excellent investments. We have designed ADUs for aging parents, long term rental income, Airbnb rentals, downsizing, barrier free living, aging-in-place, guest suites, home offices, or just to have extra space for a family.

ADUs are inherently affordable as you don’t have to buy land, and they can provide income streams while increasing your property value. They are really great investments and are growing in popularity across the country.

Question 2: How much does it cost to build an ADU?

This is almost always one of the first questions we get asked, along with how much are the permitting and design fees. Fees can vary widely depending on the specifics of your project, the scope of work, complexities of the site, your budget, style and materials used. Cost also fluctuates with the market, so prices typically rise over time. This being said, below is a rough breakdown of the the typical cost of a detached ADU project in Portland, Oregon. Depending on your location the costs could be more or less than what is shown below. For instance, in the San Francisco Bay Area, New York City, or Seattle, the construction costs would probably be about 25-50% higher. In smaller cities or towns, like those in upstate New York, or the rural towns of Oregon or Washington, the construction costs could be a bit lower.

• $200,000 to $350,000 - Construction Costs with a General Contractor (a high-end, luxury ADU could easily go much higher than top range. We have seen ADUs for over $500,000)

• $20,000 to $35,000 - Architectural Fees (typically 10% of construction costs)

• $3,000 to $5,000 - Structural Engineering Fees (around 1% of construction costs)

• $7,000 to $25,000 - Permits (The range in cost here varies greatly by the local jurisdiction. In Portland it is largely dependent on two things: 1) Is the ADU being built initially as a short term rental? If not, there is a System Development Charges (SDC) Fee Waiver. 2) Do the additional plumbing fixtures for the ADU necessitate a new water supply branch installation by Portland Water? This alone can add over $6,000 to the cost of permits.)

• $230,000 to $415,000 - ESTIMATED TOTAL PROJECT COST

As I mentioned, this is just a rough breakdown of the project costs. Location plays a big role in the cost of the project as material prices and labor expenses can vary dramatically across the country. The specifics of your property, construction access to the site, the final design and size, the quality of finish materials, appliances, fixtures and other design elements can impact this cost. With so many variables, please use these numbers as a quick estimate to help you build a project budget and conduct more research on ADUs in your area. If you have any questions or would like to run some costs and assumptions by us, please don’t hesitate to reach out.

Question 3: How long does it take to design and build an Accessory Dwelling Unit?

This is another tough one to answer as every project and client is different and some aspects are far outside anyone’s control - like the permitting process and weather conditions during construction. In my experience it can take anywhere from 12-20 weeks to design an ADU. Permitting varies greatly by jurisdiction, but in Portland we estimate permit approvals take about 10-12 weeks (where in some of the cities in the Bay Area permit review could easily take 6 months or more). Once permits are approved, we estimate 5 to 10 months to build the ADU, depending on weather conditions, material and labor availability and other unforeseen setbacks. In total that comes out to about a year from start to finish on the shorter side and maybe 18 months or so on the longer side. This timeline is for a detached accessory dwelling unit. It could be a bit shorter if you are doing an internal ADU like a basement or garage conversion.

Question 4: What services do you provide for ADU projects?

I view my role as a guide for my clients as we work through the design and construction process. I am there to see the big picture when it comes to your project, and foster the design concept through to the intimate details. This includes interviewing you to understand your goals and ideas, your aesthetic taste, and your specific needs. I then conduct research to understand the site conditions as well as the codes and regulations that will affect the project. I guide you through an iterative design process where I help you explore what appeals to you aesthetically and what you require functionally. I then coordinate the team of design, engineering, and construction professionals as we refine the design, work out the details, obtain permit approval, and turn the drawings into a built project. During construction, my job is to work with you and the general contractor that we select to build the ADU, so that your project is built the way it was intended, and that the final project meets your expectations.

In short, I help you with everything from creating a site plan, developing the architectural concept and floor plans, all the way to selecting tiles, counters, and other finish materials. I follow your project from early concept design through completed construction working with your best interests at heart.

Question 5: When should I involve a designer for my ADU project?

I may be biased, but I don’t think it is ever too early to hire a designer. We can add great value as you consider your options and refine your goals and ideas. If you are looking for a new property to buy, we can help analyze what the opportunities or challenges could be for different options. Designers can provide important pre-design services including site evaluation, feasibility studies, programming, and can help you explore options you may not have considered. Involving a designer early in the process can help avoid costly mistakes, and increase the likelihood of your satisfaction with the project. Plus, the earlier you hire a designer, the more time they have to really learn what your needs and taste is. It is my goal to design something specific to you and your site. Where the building is beautifully integrated into the surrounding context and responds to your unique needs, taste, and lifestyle.

Question 6: Don't designers add substantial cost to an ADU project?

Design fees are an investment that can actually save you money over the course of your project. Designers are focused on your project and help you make decisions that in the best interest of achieving your stated goals. This can include tracking the budget and making design decisions that keeps the project from going beyond what you can afford to build. We are familiar with general costs of materials and systems, and how design decisions could impact construction costs. We monitor your budget and can negotiate with contractors and suppliers to get preferred pricing on materials. At the same time, the design work itself can impact project cost in a beneficial way. With a strong passion for sustainable design my work aims to reduce energy and water use which can save you money over the lifespan of your project. Selecting high quality materials and systems can reduce maintenance costs or allow you to avoid costly replacements down the road. All of these savings could be much greater the upfront design fees.

Beyond just the potential lifecycle cost savings, creative problem solving can turn a difficult property into a successful building site. We can look for opportunities to take advantage of or challenges to avoid. We also spend time documenting and detailing the design decisions to avoid costly changes once construction is underway; one of the biggest reasons projects go over budget is change orders in the field. It is always cheaper to make changes on paper before construction begins.

It is also important to remember that design fees are part of your project budget from the beginning. If you come to us and say your total project budget is $350,000 then that would include all project costs. Design fees wouldn’t necessarily increase your budget beyond that number unless you decide to increase the budget. You are in control of how much you spend and it is our job to help you manage that budget to get the best results.

Question 7: How are designers compensated?

Design fees can be based on time, a lump sum, a percentage of the construction cost, or based on the project's square footage. Each design studio has their own ways of deriving their fees and billing clients. And fees can vary depending on the scope of work, included services, complexity of the project, or even how often clients change their mind or ask for design revisions. Overall, estimating design fees to be approximately 10% of your project cost will be a good starting point when developing your budget.

Having worked with over 60 ADU clients to date has provided some insight into what clients like in terms of fee structure. I have found that clients prefer to have cost certainty as they begin their project. Hiring a designer can be stressful and there are many horror stories of design fees going far above initial estimates and getting out of control. To limit this pain point for clients, I put together a lump sum fee proposal where the fees are fixed from the beginning of work and you know exactly what you will pay for our services. As long as the scope of work doesn’t change or you don’t ask us to start over partway through, our fees won’t change. Typically the lump sum fee will be 10% of the construction budget.

Question 8: What is the client’s role in the ADU design process?

The entire design process is built around our clients and making sure we understand their goals and ideas and design to meet their taste and needs. We depend on you to communicate your design preferences, functional requirements, and budget. This last one is key. It is vital that you are open and transparent about how much you expect to spend on the project. The clearer you are at the beginning the better we can serve you as we work to design inspiring spaces that meet what you are willing and able to spend. We don’t want to design something that is over budget as we want to see our designs get built.

Your timely response to questions and design submissions will help keep the project on schedule. It is also important for you to raise any concerns you have as the project proceeds, so they can be addressed in the earliest stages. Working in partnership with us will help ensure the best possible outcome for your project.

Question 9: How long does it take to permit an ADU in Portland?

We usually estimate that in Portland it takes 10-12 weeks to receive a permit. Although we have heard that some projects are getting approved on faster timelines with the electronic permit submission now in place.

It is important to point out that each jurisdiction is different so permitting times can vary greatly. Some smaller towns or cities approve projects in a few days. Larger cities like those in the Bay Area can take many months to approve a design. We recommend you call your local building department to inquire what their typical timeline is for permit approval. Or if you would like us to help you find this information let us know. We would be happy to help.

Question 10: What is the payback time for an ADU investment?

What do you think you can get for rent? I know it isn’t great to answer a question with another question but that is really the crux of the question. If you are in a high rent area like Berkeley, California you may have a payback period of 5-6 years. If you are in a smaller town with lower rents it could be 10-15 years.

The good news is that ADU actually can pay you back twice. First is the rental income they can generate on a month-to-month basis. If you rent these out as long-term rentals or even Airbnb/short term rentals you can get revenue on a monthly basis. You would just have to check that what you can get in rent would be more than the cost of the servicing the loan you use to build the unit. On top of the rental income, your ADU also adds value to your property. If or when you decide to sell the property you will get an increased return based on the ADU that adds to the value of the main house.

Crunch the numbers to verify this, but we think they are great investments.

Question 11: How are ADUs financed?

The client’s I have worked with primarily use three ways to finance accessory dwelling units: cash, home equity lines of credit (HELOC), or cash out refinances of the main house. Right now there aren’t many financing products specifically for ADUs although as they grow in popularity this is starting to change. Banks are recognizing the value they add and are starting to be more open to financing options for adding ADUs. Many cities are also working on finding ways to create financing products to make ADUs more attainable for people of all income levels. I recommend contacting your local bank or credit union to talk about what financing options they have that would cover the cost of adding an ADU.

Question 12: What is the cost per square foot for ADU projects?

No offence, but this is the wrong question to ask. Construction costs are not proportional like this. An 800sf ADU doesn’t cost $350 more than a 799sf ADU. I know many resources on the internet talk about cost per square foot and some contractors and real estate agents talk about costs this way, but with smaller projects like ADUs it just doesn’t make sense.

Put it this way, all ADUs have some things they have to have: kitchens, bathrooms, heating, water and electricity, a foundation, roof, walls, a front door. These tend to be the more expensive parts of a home. Where a full sized home can distribute the cost of these items over lots of square footage in empty bedrooms or living rooms ADUs don’t have that ability. If you did calculate the cost per square foot of an ADU it would be much higher than the square footage costs you find on other sites.

Quick example, the project image at the top was an ADU that was about 500sf and cost about $200,000 in construction costs. That is around $400/sf. or $500/sf if you include the full project cost. Now lets say we added another bedroom and expanded the living room to make that an 800sf unit. The new cost wouldn’t be 800sf * $500/sf for a total cost of $400,000. Instead it would probably be around $300,000 total, an addition of around $50,000 in construction costs.

Costs just aren’t proportional to square footage so please start thinking about total budget rather than per square footage. If you have a budget of say $300,000 we could design you a nice 400sf unit or a nice 800sf unit. In both situations we would design a project that balances your budget with your goals and needs.

I’m glad we all agree to think about cost differently.

Question 13: Can I buy a pre-designed ADU Plan?

Yes you can. Depending on the local codes and regulations there could be a predesigned ADU that meets your goals and the local rules. In fact, we sell ADU plans of projects that we have designed to offer great modern design to more people. We understand that not everyone can afford or wants to spend the time on a custom ADU design. Buying a predesigned planset may be the right path for you. It could save some money and time. However, each local jurisdiction has their own sets of rules that determine what can be built. It is up to you to make sure that the plans you buy meet the regulations where you live.

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If you have any further questions don't hesitate to send us a message. We love talking with people about their ideas and helping them consider their options. We will do our best to get back to you as soon as possible. Thanks.

This modern ADU in Portland had a construction cost of about $200,000. The clients then invested another $25,000 or so for the landscape design and construction. Including the design fees, engineering fees, and permitting cost the total project cost was approximately $250,000.

The Importance of Designing for Acoustics

Below is an expert from my newsletter discussing the acoustics of the built environment. Acoustic design should extends into the places we call home. Too often, design focuses on the visual senses. We care so much about how things look or how light impacts a room that we forget the other senses that a design should consider. Acoustics in particular can turn a beautiful space into an uncomfortable place to live. Whether it is blocking the noise of the outside, creating a quiet place to read and think, or finding ways to introduce the sounds of nature into the interior, acoustics are something that are an important consideration as I design homes.

A snowy walk through the streets of Fort Greene, Brooklyn reminds me of my childhood. It has been 17 years since I have lived in a climate that has snowy winters and it is a pleasure waking up to snow blowing past our apartment windows, covering the surrounding rooftops, and accumulating on the streets. Snow transforms the city in many ways. Often overlooked and under appreciated is how it transforms the city’s acoustics.

I love cities and have lived in some of the largest and busiest urban centers in the world. From the frigid winters of Montreal to the heat of Bangkok, the crowds of Shanghai to the artistic hub of Berlin, the outdoor paradise of Portland to my current home in New York City, each place has it’s own character and pace of life. And each has it’s own soundscape.

Almost every morning in Portland I was unpleasantly awoken at sunrise by the screech of crows. Here in NY there is a constant drone of the noises of city life. Traffic roars along Flatbush; people unrelentingly express their love of car horns; sirens grow and fade as ambulances or police race through the streets; helicopters whirl overhead as they crisscross the sky carrying police or billionaires to some important destination. The biggest downside to life in a city is this constant noise.

Snow changes all of that. Traffic dissipates as people huddle indoors. With less traffic, there are fewer car horns, reduced tires on the roads, and less emergencies needing attention - thus fewer sirens. Flights are grounded leaving the sky clear of human made sounds. Meanwhile the falling snow blankets the city with an acoustic carpet, deadening the audible soundscape.

It is refreshing, and a reminder that cities are more pleasant without the rumble and rattle we all make. The quiet streets are a joy to wander down. In the park you hear the deadened sounds of children laughing as they sled and play in the snow. An occasional dog barks. You hear the slight wind or creak of trees. The snow muffles the intruding sounds beyond the park’s borders.

We need to remind ourselves that cities don’t have to be so noisy. We can design places that have better acoustics and thus create better places to live. We can restrict traffic - either by closing streets, removing lanes, or implementing congestion pricing. Adding protected bike lanes would encourage people to drive less. Charging for parking and subsidizing public transit would further reduce car use. Electric vehicles can replace the roar of combustion engines. It would be an easy political win to ban helicopters as they are completely unnecessary and only serve a tiny handful of people.

The design of our streets, public spaces, and buildings can consider the acoustics of the urban environment just as they respond to climate, weather, and other functions. While we currently focus on how things look, we rarely discuss how the built environment impacts how things sound. I hope this changes.

Cities can be places where the noises of nature outweigh the sounds of human. Sirens and traffic could be the exception rather than the dominant force in the urban soundscape. I’d rather hear the sounds of wind, the songs of birds, or simple have quiet spaces to walk and think, even when I’m in the heart of a dense urban environment.

Subscribe to our newsletter here: lucasgray.substack.com

How Much Does An ADU Cost?

More and more people are considering having an ADU designed and built for their property, and one of the primary questions they have is how much does an accessory dwelling unit cost to build? People like you want to know how to start budgeting for ADU projects whether they are living on Bainbridge Island outside of Seattle, in Portland, OR, or down in Los Angeles, California. ADU Cost is one of the most common questions we get and we will do our best to outline the areas that impact ADU budgets below.

The problem with googling “ADU Cost”

A quick search on google for cost of construction can lead to a wide range in estimates, and most of them are not realistic, especially for ADUs. Having worked on over 60 ADUs to date we have designed everything from simple 500sf projects on flat lots to larger 1000sf ADUs on tricky sloped sites. We have a good sense of the cost ranges for these projects and what factors impact the final price. We will do our best to outline how to set your budget and then will give a breakdown of ADU costs from a recent project that you can use as starting point to build your budget.

But first, let’s discuss cost per square foot numbers and why you shouldn’t use this is a way to develop a budget for ADU projects.

Many resources on the internet, some contractors, and many clients use cost per square foot as a basis to develop a budget for residential projects. I want to urge you not to use this as a metric to analyze your ADu budget. Although this can work if you have your numbers correct, we find that it can be very misleading for budgeting an accessory dwelling unit compared to a full custom home. The main problem has to do with scale.

Just like a large home, ADUs have all the expensive parts needed to live - a functional kitchen, bathrooms, plumbing and electrical systems, windows, doors, excavation and utility work, plus design costs and permitting fees. On a large home these costs get spread out over the larger square footage and cheaper space to build, like bedrooms and living rooms. A good way to think about it would be that the cheaper rooms like bedrooms and living rooms subsidize the more expensive rooms like kitchens and bathrooms plus utility connections, etc. ADU floor plans don’t have this advantage since they are limited in size.

Not all square footage is the same cost. A bedroom is just empty space with blank walls, a couple of windows perhaps, some flooring, and a couple of doors. This is relatively cheap to build. A kitchen on the other hand has all the walls and floor, but more lighting, appliances, counters, cabinets, plumbing work, more complicated electrical, etc. It is much more expensive to build. Where a bedroom may be $150/sf a Kitchen is more like $400 or $500/sf. This means that going from a 700sf to an 800sf project can actually bring your cost per square foot down considering both have a kitchen and a bathroom. The 800sf ADU spreads those costs out over an additional 100sf.

With ADUs being so small, they don’t have the extra square footage to spread the base costs out like a larger home does. A $200,000 five hundred square foot ADU would have a cost per square foot of $400. Where a $600,000 two thousand square foot home would only be $300/sf.

The point here is that we encourage people to develop a budget and then work to design something to hit that total project number. The size of the unit is less of an impact on final cost than the form, site conditions, materials, and systems selected. Start your project knowing that the base cost of building an ADU will be about $200,000 and then the decisions you make with your design team will impact what the final cost ends up being. Our advice is usually that ADUs come in between $200,000 on the low end and $500,000 on the upper end. We have seen some luxury ADUs in the Bay Area and Los Angeles even exceed $500,000.

How Much Should You Budget For Your ADU Project?

ADUs have three main costs to build into your budget: design fees, permitting fees, and construction costs.

ADU Design Cost

For a custom designed ADU you can expect that the design cost will be between 10-20% of your total project costs. These would include the cost of an architect or designer, structural engineer, surveyor, and other consultants that may be needed. Although most people decide they want a custom designed ADU that is specific to their needs, aesthetic taste, and responds to the unique character of their property, it is possible to save on the design cost by starting with a pre-designed ADU plan set. If you are trying to bootstrap a project and reduce costs as much as possible this could be a good way to go. We sell ADU floor plans of our past projects for those looking to save time and money. Shop for a floor plan design that works for you here: Modern ADU Floor Plans

ADU Permitting Cost

Permitting fees can vary greatly from city to city, but in Portland, Oregon you can expect that the permit fees for a detached ADU would be between $6,000 and $14,000, potentially more if you are going to use the ADU as a short term rental like Airbnb or VRBO. The big range here has to do with water service and whether you will have to upgrade the water meter for the property and/or add a new water meter for the accessory dwelling unit. If you are able to simply tie in to the existing water and sewer service of the main house you would fall on the lower end of the range. However, you may want to chose to install a new water meter if you will be using the ADU for rental income, so you can pass on the water utility bill to the tenants.

ADU Construction Cost

Construction cost is the big variable and depends on the site conditions, project size, design complexity, and the selection of materials and systems. We find that with today’s construction costs building an ADU, even smaller simpler projects on flat sites, will come in at $200,000 or more. That is sort of the baseline price, and the cost can go up from there depending on some of the variables mentioned above. Building an ADU can be complicated and we don’t advise taking shortcuts to save cost.

Although $200,000 is achievable for a nice but simple ADU, in our experience, most clients decide to add features that drives the cost up from that baseline. Whether it is nicer windows, higher performing systems, nicer interior finishes, high-end appliances, or premium materials, there is almost always a decision that is made where the clients balance the quality vs price and decide to upgrade the design. For this reason, we say that the average price of an ADU is about $250,000 in the Portland market. In places like the Bay Area or Seattle the average cost for an ADU is closer to $350,000 or more. On the higher end of the scale, if you are looking for a premium luxury ADU with the top of the line systems and appliances, high-end materials, and a premium design, you can look to spend $400,000 to $500,000 or even more.

Keep in mind that these construction cost estimates are for the construction only. On top of the construction costs needed to build the ADU, there would be the 10-15% in design fees and $6,000 to $14,000 in permitting fees. When you build your budget and talk to your design team about the project costs, make sure to be clear what the costs of construction are and what the total project costs are. $200,000 in construction costs probably means a total ADU project budget of closer to $240,000.

Interior view of a studio ADU on the second floor with a home office below.

This project current being designed is on a sloped site which requires additional concrete foundation work.

Accessory Dwelling Unit (ADU) Construction Cost Breakdown:

To give you a sense of how the construction budget gets to those ranges, below we have broken down a budget for a 790 square foot ADU we designed in the Cully Neighborhood in NE Portland. This ADU is being used to generate rental income and the couple who built it plan to move into the ADU when their kids leave the house. It was designed for aging-in-place with all necessary living functions on a single level.

Below is a rough construction cost breakdown for a 790 square foot sustainable ADU that was built in the summer of 2015 in Portland, OR (we’ve inflated pricing below to reflect an average 6% construction cost increase per year since that time). This design has a few unique elements that are reflected in the cost breakdown. The design includes a high performance envelope - typical wall construction with standard batt insulation walls & roof per code, plus an additional 2” of continuous exterior insulation on all the walls, and an additional 3” of continuous exterior insulation added to the roof, plus a fully insulated slab. We also designed it to have radiant floor heating with an on-demand hot water system. There was also a couple of unique custom windows that are significantly more than standard windows would be - however they were important to the design and function of the spaces.  

Finally, this breakdown is for the construction costs and doesn't include Architectural or Structural Design Fees. The design fees vary depending on the complexity and size of your project. We recommend budgeting about 10-15% on top of the construction cost for design fees, $6-14k for permitting, and we always recommend budgeting another 10% as a contingency fund to cover any unexpected costs that may come up.

Permits: $12,000
This includes the current Portland SDC Waiver. Typically permitting fees for an ADU fall around $6-$14k. This project came in at the higher end due to the fact we had to upgrade the water supply line & meter size due to the amount of plumbing fixtures in the main house and ADU combined.

Excavation: $15,000
Around a 650sf slab area including the exterior decks. Also included excavation for a couple landscaping retaining walls on the property.

Concrete Work: Footings & Retaining Walls: $28,000
This includes work needed for the ADU plus a couple of retaining walls that were designed as part of the surrounding landscaping.

Concrete Slab: $8,000
The interior exposed concrete slab and finishing for the floor of the main level. This was poured as a separate slab from the foundation footings.

Framing and Sheathing: $25,000
Typical 2x6 stud wall construction, 2x12 roof joists, supporting structural posts and beams. The large exposed glulam beam in the center of the project was around 30’ long to span the length of the living space.

Siding: $12,000
Horizontal fiber cement siding with vertical tongue & groove cedar siding at the front entry and back patio, as well as a cedar soffit under the eaves.

Roofing: $15,000
Standing seam metal roof

Windows and Doors: $15,000
2 custom windows (including a complex window that wraps the corner of the kitchen), 3 skylights, 8’ front door with sidelite, 8’ two panel sliding door, and three large vinyl sliding windows.

Plumbing: $25,000
Includes radiant floor heating installation and an on demand hot water system. Plumbing fixtures, sump pump, fire protection sprinklers & installation.

Electrical & Fixtures: $20,000
Electrical panel, electrical wiring, outlets and switches, lighting fixtures, and installation labor.

Insulation: $12,000
Roxul batt insulation in walls and ceiling stud cavities per code, plus an additional 2” of continuous exterior polyiso insulation on all walls, 3” of continuous exterior polyiso insulation added to the roof, and a fully insulated slab on grade. (This amount of insulation is well above code requirements and is close to passive house standards. With some solar panels this ADU could easily achieve net zero energy. )

Sheetrock (Drywall): $10,000
Drywall, mudding, taping, sanding

Interior Doors: $2,500
2 standard doors, 1 pocket door and 3 closet bi-folding doors

Paint - Exterior: $5,500
One color, no accent or trim color

Paint - Interior: $8,000
One color throughout the interior.

Trim Work: $5,500
1x4 painted MDF base trim, plus clear coated fir window sills

Cabinets: $6,500
IKEA kitchen cabinets and some custom casework in laundry and bathroom

Countertops: $1,500
Ikea wood countertops material and install labor

Tile: $7,000
Kitchen backsplash and shower - materials and labor

Staircase: $3,500
Off the shelf spiral staircase kit

Flooring in Loft: $3,500
Pre-finished solid White Oak, about $8/sf plus misc. materials and install labor

Cable Railing: $3,500
Off the shelf system

Appliances: $7,000
Stovetop, oven, vent hood, dishwasher, garbage disposal, refrigerator, washer, and dryer

TOTAL: $251,000
Includes all materials, labor and contractor fees.

The budget above is fairly typical for ADUs we have worked on over the years. And it is important to point out that this wasn’t a high-end or luxurious project. There were a few places where the clients made decisions to invest more to get the result they were looking for. For instance we had some custom windows, skylights, and radiant floor heating. The rigid insulation was also an upfront cost but will pay itself back through lower energy bills for the lifetime of the project. Meanwhile, the rest of the project was pretty standard materials and systems and in some places we used cheaper than normal elements, like the Ikea kitchen. Overall, we think this is a good starting point for most people who want a high-quality, nicely designed accessory dwelling unit in Portland, Oregon.

Important Note:
Every site is different and the conditions can greatly impact cost. Excavation and concrete work costs can vary greatly depending on the topography and of the site and other conditions (is it sloped? lots of trees? poor soil conditions? Does it need extra soil removal or backfill?). Ease of access to the location of the ADU can also add costs (are there fences that need to be removed and rebuilt? Can machinery get to the location to excavate or deliver materials? will a crane rental be required?). Material selections and other design decisions you and your designer will make throughout the process will also have a big impact on cost. The outline above is a good starting out point but I guarantee your project will end up being different.

If you have any questions don't hesitate to reach out. We are always happy to talk about the unique aspects of your project and talk through your goals and ideas for a sustainable Accessory Dwelling Unit.

This ADU in the Cully Neighborhood of Portland would cost about $250,000 to build.

Interior view of the ADU’s main living space with an open loft above. A 30’ long glulam beam spans the length of the living room.

A large custom window wraps the corner kitchen, offering great views to the surrounding yard.

What Is An ADU And Why Should You Build One On Your Portland Property?

Accessory Dwelling Units, ADUs for short, refer to a second home on a property that already has a main house. Typically these are smaller than the main home and are detached structures located in the backyard. However, they can also be internal ADUs adding an apartment within the main structure. For instance, you could convert a basement into a separate apartment or renovate an attached garage into a new living unit.

Most often ADUs are built by homeowners who want to add a unit to their property to earn rental income, use as a guesthouse, or for a relative to live. People also build these for themselves in order to downsize and allow them to rent out the larger main home. With the growing popularity of ADUs around Portland and across the country, many new houses are being built with ADUs as part of the development. We see many new homes include basement ADUs as part of the selling point for new homeowners.

Portland has grown into one of the most popular markets for Accessory Dwelling Units. With recent changes in state and local laws, ADUs are now permitted on any residential property. And the city of Portland has seen applications for accessory dwelling units skyrocket over the past few years. We foresee this trend growing further as housing prices increase and limitations loosen even further. In the summer of 2021 Portland will allow multiple ADUs per property which should contribute to even more of these housing types being built.

ADUs are a great way to increase the value of your property and earn additional income by renting one out. The extra revenue can help you pay off your mortgage faster, afford a larger house or a home in a more desirable area, or just give you extra money to live more comfortably or take a nicer vacation.

As well as being a great investment for most homeowners, ADUs also are great assets for our communities. Housing costs continue to rise, often outpacing increases in income. More an more people are searching for housing opportunities that are affordable and are in desireable urban neighborhoods. Accessory Dwelling Units are a great way to address these issues. They add new housing while maintaining neighborhood character. They increase density while being sensitive to the surroundings, and the new residents also contribute to the local economy, boosting small businesses. And with the additional residents, cities get additional revenue to provide services like better public transit. They really are a win-win for everyone.

To summarize, Accessory Dwelling Units can provide rental income, an increase in property values, housing for family members, and on a neighborhood scale they create desirable growth without needing to add new infrastructure, while providing affordable homes. The new residents also will benefit the local cafes, restaurants, and shops - a boon to local businesses.

I have led the design effort on over 60 ADUs to date, with a focus on developing beautiful solutions for these project types while incorporating sustainable design strategies. I’ve developed an expertise in these projects because I believe in their ability to positively impact our communities.

Thousands of Portland residents have already added an ADU to their property, to take advantage of some of the benefits described above. I anticipate that this trend will continue to grow considering that Portland will soon allow multiple ADUs per property. It makes sense that many people who already have detached ADUs in their backyard will now consider adding another in their basement, or housing developers may create new developments with basement units and detached ADUs as a new product as the market starts demanding homes that have built-in revenue streams.

I am excited to see how this market shifts and grows over the coming years. My goal is to help guide people through the process of adding ADUs to their properties - creating beautiful and sustainable designs that are environmentally, socially, and economically responsible investments.

If you are interested in learning more about accessory dwelling units, or have questions about an ADU project you are considering, please don’t hesitate to reach out. We are always willing to discuss your goals and ideas and offer advice or design services to help you achieve your vision.

The Namaste ADU in SE Portland was designed as a modern home that opens to a Japanese inspired garden.

This ADU in NE Portland is a 2-bedroom apartment perched over a 2-car garage. The design aimed for a balance between the traditional craftsman style homes in the neighborhood with a contemporary feel.

A compact layout allows the ADU to be tucked back into the landscape, preserving private outdoor spaces for both the main house and accessory dwelling unit.

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You can learn more about Portland ADUs and the Permitting Process here:
https://www.portland.gov/bds/adu-permits

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ADUs have different names depending on where you live. We have also hear the following names used interchangeably:

Alley Apartments, Detached Accessory Dwelling Unit, DADU, Accessory Apartment, Accessory Suite, Ancillary Unit, Backyard Cottages, Basement Apartments, Carriage Houses, Garden Cottages, Garden Suites, Granny Cottages, Granny Flats, Granny Pads, Granny Units, Guest Suites, Home within a Home, In-Law Suite, In-Law Unit, JADUs, Junior Accessory Dwelling Units, Laneway Houses, Laneway Suites, Mother-In-Law Flats, Multigenerational Homes, Next Gen Units. SDUs, Secondary Dwelling Units, Secondary Suites, HGTV has popularized Tiny Houses although that often means small homes on wheels which aren’t really what ADUs are. In Hawaii they have Ohana Units (and by the way, we would LOVE to do a project in Hawaii).