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.

How do you build an ADU?

The process to build an ADU includes design, permitting and construction. Within each of those phases, there are literally hundreds of small decisions to be made and tasks to complete. Check out the full process to build an ADU below, and click into the details for more information.

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

Feasibility Study, Design & Price Lock

The Feasibility Study confirms what the budget will be for your ADU given the local requirements and your site conditions. During this phase we make a site visit to map & assess your existing utilities, plus refine our assumptions about sitework. If you’re going with a semi-custom plan, we modify your desired floor plan¬†along with exterior elevations. We present all of this in a Feasibility Study along with a Construction Estimate with locked pricing for the build. Timing: 3-4 weeks (standard plan), 4-8 weeks (modified plan)

Step 4

Construction Documents & Application

Once the floor plan, elevations & budget are approved, we will produce a full set of architectural drawings along with required calculations & reports for submission to the city for permits. If you have an HOA or Construction Loan, we will also make sure documentation is ready for submission to those entities. Timing: 3-4 weeks

Step 5

Finish Material 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 city is reviewing your plans, you’ll make your design choices. You can choose an included standard design from our LookBook or select finishes a la carte. 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 & Revisions

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. Our in-house permitting team will also let you know what plan check & permit fees must be paid. 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