How Long Does It Take To Build An ADU?

After cost, timeline is one of the most commonly asked questions by those looking to add an ADU to their property. It is important to understand the full project timeline and not just the construction phase as you begin to plan your project.

Projects can typically be broken down into 4 phases:

1. Planning and Research

2. Design

3. Permitting and Approvals

4. Construction

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The Planning and Research Phase: 4-8 weeks but potentially longer

This is vital to having a successful project as it is always easier and cheaper to make decisions on paper than when the project is under construction. It is also important to have the base research done to understand and accommodate the wide range of factors that will impact the project, from local rules and regulations, material supply availability, cost of materials and labor, interest rates and other financing information, to the specifics of the existing conditions of the property.

The length of time for this phase can vary from a few weeks to a few years depending on the client and how motivated they are to move forward with the project. When clients come to us to assist with this work, we typically estimate about 4 weeks to review the property, understand the local rules and regulations, and work with the client to develop a project budget and building program.

The ADU Design Phase: 3-6 months but sometimes up to a year

A common theme in all of these rough timeframe estimates will be that it depends on the client. Some people are quick to make decisions or just trust the design team to make decisions for them. Others want to be involved with the specifics of each decision throughout the project or may need a good amount of time to think through the options before settling on what they want to do.

We typically walk clients through a custom designed ADU process in 3-4 months. We feel that is a good balance of collaborating on the important decisions while our expert designers handle the details as we develop the permitting and construction drawings. You can then add on another month or two for the various other consultants that may need to be involved in the project. This would be consultants such as structural, mechanical, electrical, and plumbing engineers, landscape architects, arborists, civil engineers and other professionals. Most of these consultants will need the architectural design to be complete before they can carry out their work.

This is a place that starting with a pre-designed ADU plan can save significant time. If you are ok with one of the designs that are available for purchase, you can condense 3-4 months into just a couple of weeks. You would basically be skipping most of the design work and moving straight into engaging with consultants.

The Permitting and Approvals Phase: 1 month to 1 year, or more!

That range may seem crazy and we agree. This is one of the biggest frustrations homeowners, designers, and builders of ADUs have in the process. Each jurisdiction has their own rules and regulations and often there are conflicting rules between towns/cities, counties, and states. It is challenging to work through the various levels of regulation. Adding further frustration is how slow most building departments are at responding to questions as well as reviewing and approving submitted plan sets.

For some specific examples, we found that it took about 4-6 months on average to work through the permitting process in Portland, Oregon. Places in the Bay Area, like San Francisco, Berkeley, Oakland and others, the process could easily stretch out to one year or more. Seattle also has incredibly long review processes, probably falling somewhere between Portland and the Bay Area. Smaller towns or states with less regulation often work a lot faster. Places like Idaho or Texas can review and approve ADUs in just a few weeks or months, assuming the town you are building in allows ADUs, and the designs meet the local codes.

We highly recommend talking with your local building department as part of your Planning and Research phase, to get a realistic estimate of the permitting time you can expect.

The Construction Phase: 6-9 months

Once you receive approved plans from the permitting process you can break ground and start construction. From this point you could probably assume a 6-9 month construction timeframe. Of course this could vary based on your local climate, material supply, labor market, etc. Also, some contractors have larger crews and may move quicker. You may also chose to work with someone who will take their time and be a bit more meticulous with the construction details to deliver a higher quality final result. Sometimes taking longer is prefered.

Remember a few key things: starting construction in the spring is ideal as you will hopefully avoid delays due to winter climate conditions (freezing cold, snow and ice, and heavy rains can delay construction significantly). In the post covid world, material supply chain and skilled labor are significant challenges to overcome. There are significant delays in getting some key building materials, especially windows, that could significantly extend the construction timeframe.

The construction timeline for building an ADU can also vary based on the type of ADU. Converting a basement or attic, or even a garage could potentially be a bit quicker to complete vs doing a ground up construction. Working within an existing structure - assuming it is weather protected - may not face climate caused delays and also may reduce some of the work such as pouring foundations or doing significant framing.

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Overall ADU Timeline

If you are just beginning to consider adding an ADU a good safe estimate is it would take about 12-18 months from start to finish. That would include pre-design research, the architectural design phase, permitting approvals, and construction. Of course some jurisdictions - I’m look at you Bay Area - will probably throw some wrenches in the gears and take too long to review your project and issue permits, so it could take longer.

To bring this timeframe down you can consider strategies like starting with a pre-designed ADU, or even an prefabricated or modular ADU. It is also wise to plan for a a springtime construction start, and to hire your design team and general contractor well in advance so they can collaborate and plan for a successful construction process. The best time to start design would be late summer or early fall with the goal of starting construction the following spring or summer.

If you are starting a project and have any questions don’t hesitate to reach out. We are always happy to help you get on the right track. And if you want to cut down on your timeline and want to start with a pre-designed ADU plan check out our available designs by clicking the button below.

Design Process: Additional Services

We have outlined the general phases of the design process in earlier posts. However, there often are other services that we offer to make your project easier to achieve. None of these are required to get an ADU designed, permitted, and built, but some can make your project a greater success or take some work off your plate so you can focus on other things. Additional services for ADUs or Custom Homes allow us to customize the service offerings to the unique needs of each client and each project.

Property Search and analysis (Feasibility Study)

You are looking into buying a new home and want to know what the potential is to add an ADU as a rental unit. Or perhaps you want to analyze your current property to better understand the opportunities and challenges for adding an accessory dwelling unit or other property improvement project - like a major addition, remodel, or even a new custom home design. It is also a great idea to do a feasibility study when considering purchasing of a piece of land. If you are considering any of these options a feasibility study is highly recommended as the first step. Whether you hire us or engage another design team, it is worth investing in this preliminary research before you commit to a larger project or before you close on a property purchase. Zoning research, site analysis, property review, and other research is can save significant money or prevent you from beginning a project before knowing exactly what is allowed. Whether you are considering an ADU, a major remodel, or a custom home design, this is a valuable service that is worth the upfront investment.

Interior Design

Some clients love shopping for materials, finishes, appliances, and picking out colors and other interior elements for their homes and ADUs. Others don’t have the time and want someone to assist with this process. Since most interior finish selections don’t affect the permitting process this service isn’t necessary to get a custom home or ADU approved to build, but it can make a big difference for the look and feel of your project. An interior design that matches the aesthetics of the exterior and creates a welcoming environment can make or break your project. And interior design is especially important if you are planning to rent out the ADU as a long or short term rental. You want durable materials and finishes as well as a noteworthy, photogenic design that will set your rental apart from the competition. This service can include selecting all of the finishes like tile, counters, cabinets, fixtures, and hardware or can include additional tasks like helping select furniture, artwork, and other decorations to bring the space together and feel warm and inviting. Custom home and ADU Interior Design can take a great deal of time and effort but can have a great return on investment. This is why we recommend that our clients hire a professional designer to assist with this work. Typically we like to work with you to at least select all of the materials, finishes, and fixtures that will be attached to the structure which is why we offer interior design as an additional service for our ADU and custom residential clients.

Existing Conditions Drawings (As-Builts)

Most of the projects we work on are detached new construction ADUs or custom residences. However, when an ADU interacts with an existing structure on your property it is necessary to document the existing conditions. Often these are called as-built drawings, and include creating dimensioned drawings of all the existing spaces and structures that will be affected by the project. Most designers will offer this service or sub-contract it out to another drafting company. It is worth the investment to get an accurate drawing set that shows the current conditions of your home before you start any project.

Renderings

Three dimensional views of the project are another part of the design process that isn’t necessary for the permit approval process but can be a great tool to make design decisions. Taking these views a step further, you can use modeling and drawing software to create rendered views that show materials, finishes, lighting, furniture, people and other effects to really show what the spaces will look and feel like. We often do a couple exterior and a couple interior renderings so our clients can see an approximation of what their project will look like after it is finished. This allows them to have the confidence they will like the final design prior to starting construction. Good renderings do take time and thus cost money, but we always find it is worth spending a bit of extra effort during the design phase to prevent changes or worse, regrets, once construction begins. A couple thousand dollars during design can save tens of thousands during construction. If you are unsure about what your project will look like or how the interior spaces will feel by looking only at plans, sections, and elevations, ask your design team to make some renderings. It is an added service but can give you a better sense of the final project plus are great to share with friends and family so they can see what you are planning!

Physical Models

These are pretty rare these days as most firms have moved to digital drafting and 3D visualization software. However, some clients think better when seeing a physical model of their new home or ADU. We have built a few models for clients and they can be a valuable tool to help make design decisions. They can be time consuming if you are looking for a lot of detail. Simple massing models, or chipboard diagrammatic models can be quick and cheap, but detailed wood models can be very time consuming and could add significant cost to the design process. Still, like with the renderings, it is still cheaper to invest in the design process than try to make changes once construction begins. It is better to be sure about the design direction and sometimes physical models are the best way to think through a design challenge or capitalize on an opportunity.

Meetings and Presentations: Design Review, Community Engagement, Neighborhood Associations, Historic Review, and other meetings or presentations.

Certification Process & Applications: LEED, Earth Advantage, Passive House, Net Zero, or other certifications.

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Other Articles in Our Design Process Series:

1. Phase I - Predesign

2. Phase II - Schematic Design

3. Phase III - Construction Documents

4. Phase IV - Permitting and Bidding

5. Phase V - Construction Administration

Healthy Indoor Environments for ADUs and Custom Homes

There is so much more to developing a design for an ADU or Custom Home than just making a beautiful building. Our approach balances aesthetics, sustainability, high performance, and maybe most importantly, healthy indoor environments.

Great design creates healthy environments.

According to the EPA, “Americans, on average, spend approximately 90 percent of their time indoors, where the concentrations of some pollutants are often 2 to 5 times higher than typical outdoor concentrations.” Armed with this data, we look for ways to make our buildings healthy places to live to avoid polluted environments that can negatively impact your health. The most beautifully designed home is a not a success if it isn’t also sustainable and a healthy place to live. A great home needs to do all of the above.

Indoor Air Quality

Indoor air quality is one of the many considerations that guide decisions during our design process for both custom homes and custom designed ADU projects. From creating spaces that have natural ventilation and can open up to the outdoors, to selecting materials that minimize toxins and off-gassing, we help guide our clients through the decision making process that leads to a healthy home. This includes selecting natural materials (like plaster instead of gypsum board), low VOC (volatile organic compounds) paints and adhesives, and heating and cooling systems that filter out contributors to indoor air pollution. A home shouldn’t contribute to conditions such as asthma, allergens, or other irritants, and the design process can help avoid these conditions.

Open to the outdoors

Before we look to mechanical systems like air filters on an HVAC system, we look for opportunities to create passive ventilation in our homes. This includes operable windows in the areas people spend most of their time - bedrooms, living rooms, kitchen and dining areas - and other ways to make use of natural ventilation for airflow, like natural convection to create airflow. The orientation of the building, sun shading, and other passive strategies can also limit the use of active systems that can move dust and toxins throughout a home’s interior.

A common design element we use in a lot of our projects are large sliding doors that completely open up spaces to the surrounding landscape. Living in connection to nature can help make our indoor spaces healthier and more enjoyable - bringing in fresh air, natural light, as well as views into the beauty of nature.

Don’t compromise on health

When creating a home for a family we don’t believe in compromising between a high performance healthy home and great design. A healthy indoor environment is part of our thinking from the start of each design. It as integral to our process as developing efficient floor plans, beautiful aesthetics, selecting high quality materials, and integrating sustainable strategies. It is only when all of these things come together that a project meets the needs of our clients and becomes a great place to live. By adding an ADU you are taking a great first step into building a sustainable home.

A custom home in an urban area wraps around a central courtyard so all rooms have access to natural light, natural ventilation, and have views to the outdoors. Natural materials, low VOC paints and adhesives, and high quality air filters on the HVAC system round out the strategy to create a healthy indoor environment.

Frequently Asked Questions about Designing and Building Custom Homes

How does the design process work?

We have a set design process that we lead you through in order to deliver the best results. We break down each project into 5 phases so there is a clear and predictable path that each project moves along. We have outlined this process in detail in another post. Click the button below to learn more.

How long does it take to design a Custom Home?

This can vary greatly from project to project depending on the specifics of the property, the size of the home, and the clients. If you can make decisions relatively quickly we can design a home in 6-9 months. If you want to take your time and deliberate longer on decisions than a 1-year design timeline is a good rough estimate. Keep in mind, this is for the design work. The permitting review and construction process would be added on to these estimate. For a rough order of magnitude you can anticipate 1.5 to 2 years total from start to finish. As we mentioned in our Value statement, we want to serve the best interest of our clients and that takes time. Like the growth of the slow food movement as a pushback against unhealthy fast food, we believe quality is vital and working diligently through our process leads to the best results. And the best results take time.

How much does it cost to build a custom home?

We expanded on this in more detail here. However, as a quick estimate you can assume a custom home would start at around $1 million and go up depending on the size, the site, the quality of materials, systems, and other elements in the project. Your overall budget is really about your goals and ideas and how much you want and are able to spend on the project. We have design small homes, ADUs, that were around $300,000 and we have designed full custom homes for $1,000,000. Larger, higher-end, homes are easily $2 million or more. It really depends on what you are specifically looking for. We start our design process by interviewing you to better understand your wants, needs, goals, ideas, and lifestyle so we can deliver a project that is unique to the specifics of your life and property.

What is included in the design fee?

When any client first contacts us we listen to their goal and ideas, we then ask questions to get an intimate understanding of what they want and need, and what their lifestyle is so we can best craft a solution. Based on this analysis of the uniqueness of your project, we develop a proposal that is specific to your project and the value we can provide as designers and advisors. We also offer tiers of services that you can select to best serve your needs, expectations, and budget. This is a long way of saying, “it depends.”

Generally speaking, our design fees cover Predesign, Schematic Design, Construction Documents, Permitting, and Construction Administration. These are the five phases we guide each project through from our first meeting to handing you the keys to a beautiful custom home. You can learn more about what each of the phases covers by reading the Design Process post linked above.

What other expenses should I expect?

Outside of the design fees there are a handful of expenses that you need to consider. First is the construction cost, of course. This would be the cost of materials and labor paid to the General Contractor. There will also be a handful of consultants needed to complete your project. This includes a surveyor, structural engineer, perhaps a Civil Engineer and Geotechnical engineer (these depend on the property and full scope of design work), arborists, and landscape designers. There may also need to be energy consultants or other special consultants depending on the local requirements.

Other than construction costs and consultant fees, the other major expense will be the Permitting fees assessed by your local jurisdiction. Each city and town is different and has different fee structures so we will conduct that research and report on estimated permitting costs during our Pre-design phase.

How will I know that I will like the end result?

Design is an iterative process and involves sharing ideas, discussing your style, taste, preferences, needs, and wants. It is our job to listen to you, learn about your lifestyle, and understand what you are looking for and then transform that into a design of your custom home. Throughout the design process you will sit down with us as we present design ideas, floor plan layouts, and other drawings to describe the look and feel of your home. Together we will talk through pros and cons of different options and actually sketch ideas as we refine the design into a beautiful home that reflects your values. This iterative process has led to successful designs that our clients love as well as designs that have been recognized and won awards from the design community.

It is also recommended that you look through our portfolio, follow our instagram account, and make sure that our style and values are aligned with what you are looking for. We tend to design modern or contemporary styled projects that are connected to nature and influenced by the landscape around them. If you are looking for a craftsman style suburban home we probably aren’t the right designer for you. However, if you like the work you see on our website, I’m confident that we can design a beautiful project that you love and are proud to call home.

What drawings are included in your services?

There are two main drawing sets that are created during our design process. There is the Schematic Design set and the Construction Documents set. Each has their own specific drawings that are included. For the SD set we include a site plan, floor plans, elevations, sections, and 3D views to describe the design intent. However, to arrive at the final drawing package we do a lot of drawings as we present options and work through the iterative design process. There are a series of plans, elevations, 3D views and hand sketches that we create and use to talk through design ideas along the way.

The Construction Documents Set includes all of the drawings that are needed to both receive a permit from the local building department as well as the information needed for a General Contractor to bid and then build the project. This includes but is not limited to: general notes, a detailed site plan, dimensioned floor plans, building elevations, building sections, foundation plans, reflected ceiling plans, enlarged floor plans, interior elevations, assemblies, schedules, construction details, finishes, fixtures, and equipment lists, and structural engineering and other drawings provided by the consultant team.

Who manages the permitting process?

It is part of our standard scope of work to oversee the permitting of our projects. This includes compiling the permit drawings, filling out permit applications, and submitting all of this to the local building department. We then follow up to respond to any review questions or requests for additional information. There may be a few forms you are required to sign as the project owner, but otherwise we manage the process on your behalf.

Do you have experience working in my local area?

I have worked across the country and around the world and have had success on projects regardless of location. I worked remotely on a project in northern Alberta and I worked with communities as far away as rural Japan. I lived and worked in Thailand, China, and Germany. In earlier years I worked on the design of train stations in Russia, renovations in Berlin, and ADUs in Seattle and the Bay Area. I’ve lived and worked in Portland, Oregon and designed over 100 projects across Oregon. My home base is currently Brooklyn, NY but I travel frequently for work and pleasure. The point is, I may have some experience in your area but I also know how to work in different locations. Regardless of the location of the project, I do the research needed to understand the local rules and regulations, the local permitting process. I collaborate with local contractors and craftspeople, and of course I visit the site to understand the unique aspects of your property and the surrounding landscape.

Do you stay involved during construction?

Absolutely. It is vital to have your designer follow the project through to completion. There are always some adjustments when translating drawings into a built home and we are there to help answer questions, make suggestions, and observe that the construction is following the design intent. I will be an advocate for you during the construction process to get a high-quality home that aligns with the values and design ideas we worked on throughout our design process. A designer stepping away during construction is irresponsible and doesn’t have their client’s best interest at heart. Construction Administration is an important part of our standard services for all residential projects.

Do you have builders/General Contractors you can recommend?

Recommending contractors is part of our services. Working with trustworthy, high-quality contractors and craftspeople is key to the success of a project. In places where we have already completed projects we can recommend people we had great working relationships with. In new locations we do an extensive search to find qualified contractors to collaborate with. This means reviewing contractor websites, talking to local designers, architects, and engineers to get recommendations. We reach out to the companies that have a good reputation and interview them and ask for references to follow up with. Ultimate we typically recommend about 3 companies for each project and have you meet with them. It is important that you meet and get a good feeling for the contractor as they will be a big part of the success of your project. We want to make sure you have a good feeling about them and they are both excellent communicators and have the experience needed to build a finely crafted home.

Can we make changes to the design during construction?

Changes during construction are not recommended. Change orders are often what causes budgets to get out of control. It is always much more expensive to make changes during construction than working out design options on paper. It is also important to consider that there are many factors that influenced what was design. Changes during construction can affect structural systems or may not meet codes that were considered during the initial design. Even when contractors make suggestions for changes in order to save money, we find that often it ads as much expenses and what they think they will save. Major changes require additional drawings and details to document what is changing and need to be reviewed by the jurisdiction as a permit revision. And even small changes can cause delays and additional costs. For these reasons we highly recommend that once construction begins we all stick to the original design.