How Long Does It Take to Build an ADU in Richmond?
Most people asking about an ADU want one number. How long. The honest answer is that the build itself is often the shorter half of the project. Paperwork comes first, and it takes real time.
Here is how the work usually sequences, and what you will be doing or waiting on during each stretch.
The short version
For a new detached ADU, plan on roughly nine to eighteen months from your first design meeting to a finished building you can move into. Design and permitting usually eat three to seven months of that. Construction on a detached unit commonly runs five to seven months.
A garage conversion or an attached unit is faster on the build side, often three to five months, because the foundation and shell already exist. Permitting is not always faster, though.
Weeks 1 to 6: design and decisions
This phase is you making choices and a designer putting them on paper. Site measurements, setbacks, utility locations, septic or sewer, where the unit sits in the yard, how it is accessed, how many bedrooms, where the kitchen goes.
Expect two or three rounds of revisions. Each round adds a week or two. The faster you give feedback, the faster this moves. This is also where structural engineering and energy compliance documents get produced, which can add a couple of weeks after the floor plan is settled.
Use this time to get a sense of scope and budget. Square footage, foundation type, whether the sewer lateral or electrical service needs upgrading, and your finish level are the four things that move the number most.
Weeks 6 to 24: permit review
You submit a complete set of drawings, then you wait. Plan check for an ADU is commonly six weeks to four months depending on the jurisdiction's backlog and how complete the submittal is.
You will almost certainly get correction comments. That is normal, not a sign something went wrong. Your designer responds, resubmits, and the file goes back in line for a second review. Each cycle adds a few weeks.
Separate items can run in parallel here. Utility coordination for a new electrical service, sewer or septic review, and any school or impact fees all get sorted before you receive the permit.
Weeks 1 to 2 of construction: site work
Once the permit is issued and we have a slot on the calendar, work starts. The first two weeks are the least visually satisfying and the most disruptive to your yard.
Fencing, access path, portable toilet, dumpster. Demolition if a structure is coming down. Excavation, trenching for water, sewer, and electrical. Grading. Underground inspections happen before anything gets covered.
Weeks 3 to 5: foundation
Forms, rebar, inspection, pour, cure. Concrete sets its own schedule and rain can push it. After the pour there is a waiting period before framing can load the slab or stem walls.
Weeks 5 to 9: framing and dry in
This is the fast, loud part. Walls go up, then the roof structure, then sheathing. Within a few weeks you go from a flat slab to a building with a recognizable shape. Windows and exterior doors get set, roofing goes on, and the building gets weather tight.
Framing inspection happens before anything is covered. If windows have long lead times, this is where that shows up, so order them early.
Weeks 9 to 13: rough plumbing, electrical, and mechanical
Pipes, wires, ducts, and the heating and cooling equipment all go in while the walls are open. Three separate trades, usually overlapping. Each one gets inspected.
Progress looks slow from outside because nothing changes on the exterior. It is not slow. This is the phase where a missed decision costs the most, so lock in where outlets, lights, and the water heater go before it starts.
Weeks 13 to 16: insulation and drywall
Insulation, inspection, then drywall hang, tape, and texture. Drywall mud needs drying time between coats. The interior starts to feel like a house.
Weeks 16 to 22: finishes
Interior and exterior finish work often overlap. Siding, exterior paint, and final grading happen outside while cabinets, countertops, tile, flooring, interior doors, trim, and paint happen inside.
Countertops are measured after cabinets are installed, then fabricated, so there is a built in gap of a week or two.
Weeks 22 to 26: trim out, inspections, and punch list
Plumbing fixtures, light fixtures, outlets and switches, appliances, hardware. Final inspections from building, electrical, plumbing, and mechanical. Then the certificate of occupancy.
A punch list follows. Touch up paint, adjusting doors, small corrections. Budget a week or two for it and do not plan a move in date on the day of final inspection.
What actually causes delays
- Correction cycles during plan check, usually the single biggest variable
- Long lead items such as windows, cabinets, and electrical panels
- Utility coordination for a new service connection
- Change orders after framing, which ripple through every trade behind them
- Rain during excavation, foundation, and roofing
- Inspection scheduling, which is out of everyone's hands
How to keep it moving
Make decisions early and in writing. Pick finishes before drywall, not after. Keep the yard clear so crews are not working around stored items. Answer questions the same day when you can.
If you are weighing an ADU in Richmond and want a realistic schedule for your specific lot, get the site walked before you commit to a design. The site usually tells you more about the timeline than the floor plan does.