How long does a detached adu project really take in San Francisco, CA?

39–72 weeks from contract to keys for a typical San Francisco detached adu, end-to-end including SF Department of Building Inspection plan check. The low end assumes a clean parcel, no overlays, and scope locked at contract; the high end assumes overlays, plan-check corrections, and one long-lead material slip.

What's the longest single phase on a San Francisco detached adu?

Almost always permit + plan check, not construction. SF Department of Building Inspection runs multi-round corrections on most submittals — that single phase eats more calendar than framing.

Can a San Francisco detached adu be done faster than the typical band?

Sometimes — if scope is locked before design starts, the permit package is "clean" on day one, and long-lead materials are pre-purchased at design lock. We've delivered San Francisco detached adu projects 15–25% under the band when all three conditions hold.

What slows down a San Francisco detached adu the most?

Scope changes after permit submittal — every change resets the plan-check clock.; Discovering hidden conditions at demo (knob-and-tube, hidden moisture, undersized footings) — we budget 1–2 weeks contingency per major scope.; SF Department of Building Inspection seasonal queue depth — spring/summer submittals routinely run 2–4 weeks longer than winter ones.. Each of those alone can add 4–10 weeks; stacked, they're how a 6-month project becomes a 12-month one.

When should I start a San Francisco detached adu project to finish before summer / winter?

Backwards-plan from your target close-out date by the high-end estimate (72 weeks). For a Memorial Day move-in, that means contract signed by the prior September. We share a written month-by-month calendar at contract so the dates are explicit, not implied.

How much does Coastal Zone review add to my San Francisco detached adu timeline?

4–10 weeks on top of the building permit when the parcel is inside the Coastal Zone. The CDP and building permit run in parallel where possible, but the CDP almost always controls when work can start.

San Francisco Detached ADU timeline — 39–72 weeks end to end

Every detached adu project in San Francisco has the same five phases — design, permit, long-lead material, construction, closeout — but the calendar moves city by city. Below: the realistic 39–72-week band for San Francisco in 2026, what controls each phase, and the three highest-leverage moves to keep the schedule tight.

The San Francisco detached adu calendar, phase by phase.

1. Design & planning
5–10 weeks
Site walk, feasibility, schematic design, then full construction documents. For San Francisco detached adu, the schedule-killer here is usually waiting on the survey + soils letter — we order them in week one so DD doesn't stall on missing inputs.
2. Permit & plan check
15–25 weeks
SF Department of Building Inspection plan check plus 7 weeks of stacked overlay review. We submit a "clean" package — full Title 24, structural calcs, and site plan tied to the same revision — to land first-round comments instead of a hard reject.
3. Material ordering & long-lead
4–10 weeks
Lead-time-critical items (custom windows, panel upgrades, custom cabinetry, slab counters) get ordered the day permit issues. San Francisco detached adu projects most often stall on window lead times — we lock the order at design lock, not permit lock.
4. Construction
14–24 weeks
Demo through finish, on a published 2-week look-ahead. San Francisco detached adu crews work a 6-day week through framing and a 5-day week through finishes — that's how we stay inside the band rather than drifting.
5. Inspection & closeout
1–3 weeks
Final inspection, certificate of occupancy (if required), warranty paperwork, and walkthrough. We bank inspection slots a week in advance so closeout doesn't drift.

Total: 39–72 weeks contract to keys.

How San Francisco weather shapes the schedule.

San Francisco's marine layer drives June/July fog mornings — exterior paint, stucco, and roof finishes get scheduled around dew point, not the daily forecast. California rainy season (mid-November through March) compresses exterior phases — siding, roofing, and exterior trades get sequenced into May–October when possible.

On a San Francisco detached adu, the permit and the utility service request run in parallel — never sequential — because the utility lead is the longest single timeline (8–16 weeks for a panel upsize or new water tap).

What speeds it up

⚡Lock scope before design starts — every change after DD adds 1–3 weeks.
⚡Order survey, soils, and as-builts in week one of design.
⚡Submit a "clean" permit package (Title 24 + structural + site plan all on the same revision) to skip a correction round.
⚡Open utility-service request (water meter, electrical capacity) the same day we submit SF Department of Building Inspection permit.
⚡Pre-purchase long-lead items (windows, panel, cabinets) at design lock, not permit lock.

What slows it down

⏱Scope changes after permit submittal — every change resets the plan-check clock.
⏱Discovering hidden conditions at demo (knob-and-tube, hidden moisture, undersized footings) — we budget 1–2 weeks contingency per major scope.
⏱SF Department of Building Inspection seasonal queue depth — spring/summer submittals routinely run 2–4 weeks longer than winter ones.
⏱Coastal Development Permit appeals — even a denied appeal adds 6–10 weeks to the calendar.
⏱Missing a historic / design-review board meeting costs the full cycle — typically 4–6 weeks.

Verify with San Francisco's authorities.

Timeline questions.

How long does a detached adu project really take in San Francisco, CA?: 39–72 weeks from contract to keys for a typical San Francisco detached adu, end-to-end including SF Department of Building Inspection plan check. The low end assumes a clean parcel, no overlays, and scope locked at contract; the high end assumes overlays, plan-check corrections, and one long-lead material slip.
What's the longest single phase on a San Francisco detached adu?: Almost always permit + plan check, not construction. SF Department of Building Inspection runs multi-round corrections on most submittals — that single phase eats more calendar than framing.
Can a San Francisco detached adu be done faster than the typical band?: Sometimes — if scope is locked before design starts, the permit package is "clean" on day one, and long-lead materials are pre-purchased at design lock. We've delivered San Francisco detached adu projects 15–25% under the band when all three conditions hold.
What slows down a San Francisco detached adu the most?: Scope changes after permit submittal — every change resets the plan-check clock.; Discovering hidden conditions at demo (knob-and-tube, hidden moisture, undersized footings) — we budget 1–2 weeks contingency per major scope.; SF Department of Building Inspection seasonal queue depth — spring/summer submittals routinely run 2–4 weeks longer than winter ones.. Each of those alone can add 4–10 weeks; stacked, they're how a 6-month project becomes a 12-month one.
Does San Francisco weather affect the detached adu schedule?: San Francisco's marine layer drives June/July fog mornings — exterior paint, stucco, and roof finishes get scheduled around dew point, not the daily forecast. California rainy season (mid-November through March) compresses exterior phases — siding, roofing, and exterior trades get sequenced into May–October when possible.
When should I start a San Francisco detached adu project to finish before summer / winter?: Backwards-plan from your target close-out date by the high-end estimate (72 weeks). For a Memorial Day move-in, that means contract signed by the prior September. We share a written month-by-month calendar at contract so the dates are explicit, not implied.
How much does Coastal Zone review add to my San Francisco detached adu timeline?: 4–10 weeks on top of the building permit when the parcel is inside the Coastal Zone. The CDP and building permit run in parallel where possible, but the CDP almost always controls when work can start.

Plan the rest of the San Francisco project.

Plan the San Francisco schedule around plan check, not after it.

We map SF Department of Building Inspection review windows, utility coordination, and inspection sequencing into a real calendar — not a hope.