Read on for the overall project phases and typical ADU construction timeline working with Snap ADU to build your granny flat in San Diego County.

How long does it take to build an ADU?

The entire process of designing, permitting, and building an ADU will take 8-12 months depending on complexity of your design, the city in which you are located, and your site conditions. Design is roughly 3-4 months, permitting 3-4 months, and build out is 3-4 months. See below the steps and how long each phase takes.

We’re here to support you, whether you have plans ready to quote & build or are still in the learning & conceptual phase. From our first contact, we'll monitor where you are in your project so we can follow up in a way that is most useful to you... and you can expect that same customer focus as we design & build your ADU.

Step 1

Free Consultation

We will want to learn about your site location & requirements, building size & specifications, as well as your vision for the finishes in the unit. We’ll want to know which ADU plan is closest to what you’re looking for as a starting place for the design. From there, we can provide high-level feedback on feasibility & cost. Timing: 1-2 days

Step 2

Sign Proposal

We will deliver a proposal laying out our process & fee schedule with budgetary pricing for the entire project. This gives you a comprehensive view of anticipated all-inclusive costs from the outset of the project. Signing the proposal authorizes us to begin the Feasibility Study (and we always bill after the work is done). Timing: 1-2 days

Step 3


The Site Plan & Feasibility Report confirms what the building envelope will be for your ADU given the local requirements and your site conditions (we also factor in constraints like septic system and HOA if relevant). Then we lay out your desired floor plan along with exterior elevations. We can flip or mirror a standard plan to best work with your lot constraints. We can also modify our plans based on your input & requirements. We ask for a mark-up with your changes to ensure we are on the same page and move swiftly through the design phase. Timing: 8-10 weeks (standard plan), 10-14 weeks (modified plan)

Step 4

Construction Documents

Once the floor plan & elevations are approved, we will produce a full set of architectural drawings along with required calculations & reports for submission to the city for permits. Concurrently, we will refine your construction estimate, working with you to ensure the design will fall within your budget. Timing: 4-6 weeks

Step 5

Design Selections

We like to have our clients make interior & exterior design selections early in the process to ensure we can keep your project on time and on budget. While the architect is working on construction drawings, you’ll make your design choices. You can choose an included standard design from our LookBook, select finishes a la carte, or work with our designer to create a full custom look for your ADU. Ultimately, our goal is to specify upfront which materials will be used so we can keep the project rolling smoothly. Timing: 2-4 weeks (concurrent with other phases)

Step 6


You may want to pursue financing options, such as using a line of credit or construction loan. We ensure you have the required plans, scope of work, and budget to submit to a lender for any loan requirements. We can also make recommendations for lenders who work with construction loans for ADUs. Timing: 6-12 weeks (concurrent with other phases)

Step 7

Permitting & Guaranteed Price Maximum

We submit plans to the city & pull required permits. We work closely with the building department to ensure submitted construction plans move as swiftly as possible through plan review & permitting processes. After we receive revisions from the city, we also produce your guaranteed price maximum for construction. Timing: 12-18 weeks

Step 8

Build Out

Once we have permits, construction can typically start moving within a week. We handle the entire process, all the way to the final punch list with you to make sure your ADU meets or exceeds your expectations. Timing: 14-18 weeks