The cost to build an ADU (Accessory Dwelling Unit) in the Bay Area, like any other type of housing construction, depends on many factors: size, construction method, location, and the age of your property. In addition, elements specific to your particular ADU, like utilities, topography, and accessibility, also come into play when considering the ADU cost in the Bay Area, which will vary from the ADU cost in California as a whole due to the Bay Area’s expensive housing market.
Conversions of existing habitable space will come in at the lower end of the ADU building cost range of just under $100,000 to possibly over $250,000. These can be done for less cost because you are taking a finished portion of an existing house. Conversions of non-habitable space, such as ADU garage conversions, will likely fall toward the higher end of the above range, and possibly more. Garage conversion floor plans often take advantage of some of the basic structural elements already in place, but in some cases, the garage is in such poor condition that you are better off tearing it down and starting from scratch. In these cases, or for anyone looking to build a brand new ADU from the ground up, costs can be upwards of $400,000 for a unit of decent size and quality.
Size does matter, and the average cost of a 650-square-foot ADU will run around $325,000 to build ($500/sq ft), while a 350-square-foot ADU will be around $175,000 ($500 sq ft). In general, the larger the unit, the cheaper the cost per square foot is likely to be; so the cost per square foot for a 1200 square foot ADU should be less than that of smaller units.
While these costs may seem high, if you consider what it costs to buy a home in the Bay Area, you may be feeling a lot better about the cost to build an ADU. What’s more, if the unit is to be a rental, it is likely to pay for itself over time. This is new territory for many property owners, however, and it pays invaluable dividends when you work with an ADU expert that can not only help you navigate the ADU building process, but the viability of your particular project as well.
ADU COST BREAKDOWN
Cost To Build an ADU: Feasibility Study
A common process among ADU specialists in the industry is to first conduct a feasibility study, which is likely to be a flat fee. A thorough feasibility study should always include an on-site inspection and customized financial analysis. Keeping this a separate cost from the overall fees protects the property owner in the event they ultimately decide not to proceed with the project (or resource).
Cost To Build an ADU: Design
The design phase comes next and typically represents less than 10% of total project costs. A professional draftsperson or licensed architect should scope the design based on the findings in the feasibility study. While the use of a licensed architect is not always required (it is for many multi-family properties), it offers you the peace of mind that you are working with an experienced and properly insured professional who is likely able to get plans approved quicker and with less hassle.
Cost To Build an ADU: City Approvals
With a complete design in place, you can then move onto city approvals, which is another step where you will benefit from partnering with an ADU professional. Familiarity with ADU building processes and requirements of local jurisdictions can keep the time spent on this phase on the lower side. Everyone can agree that the Bay Area – and California as a whole – is in dire need of affordable housing, but it must be safe and properly approved and permitted. During this stage, your costs will include additional fees to your architect for plan check revisions and, depending on your local jurisdiction—permit fees—which typically run from 5-10% of the estimated construction costs.
Cost To Build an ADU: Building Construction
Next comes the building phase. ADU construction cost represents the majority of the ADU cost overall. Contractors typically quote construction costs on a per-square-foot basis, which is generally assumed to be between $200-$400/square foot; however, as we all know in the Bay Area, these numbers can be much higher, especially in a good economy. Again, converting existing habitable space can lower the costs. If permit fees have not already been paid, they will be during this phase when your contractor goes to pull the permits.
ADU Cost Bay Area Outlook: Optimize the Value Of Your Property!
The smartest way to look at the cost to build an ADU in the Bay Area is to look at the potential of your longer-term investment and the value you’ll be creating. This can be both through the generation of passive income and the resale of your property, whose value can be increased substantially with the addition of a well-designed, well-built ADU. The cost to build an ADU in California, in general, should increase the value of your existing property.
Whether you’re considering the addition of an ADU garage conversion, granny flat, basement conversion or multi-family ADU, Adapt Dwellings are The Bay Area Experts. When you partner with Adapt Dwellings, you don’t just get experts in ADUs; you also benefit from our expertise in local real estate services and property management. We are committed to affordable housing in the Bay Area, and we believe that accessory dwelling units are an important part of the solution.
