ADU PLANS
ADU plans drawn for your lot and your city, at a fixed price
Detached backyard unit, attached addition or garage conversion: we draw the permit set your building department asks for and quote it before you pay. You bring the design idea, or we lay it out from your sketch.
- ✓ Site plan with setbacks and utility runs
- ✓ Floor plans, elevations, sections
- ✓ Electrical and plumbing layouts
- ✓ Title 24 or REScheck energy forms
- ✓ Separate sets when your city wants them
What ADU plans cost
A new detached ADU under 1,200 sq ft is priced by sheet at $195 per sheet, and most need 10 to 13 sheets, so expect roughly $1,950 to $2,535. A garage-to-ADU conversion or an attached ADU built as an addition is priced at $1 per square foot of drawn area with a $1,200 minimum, which covers most of them.
Small ADUs cost more per square foot to draw because the sheet count barely shrinks with the footprint: a 400 sq ft cottage still needs a site plan, foundation, framing, sections, electrical, plumbing and energy compliance. We'd rather publish that than pad small quotes quietly.
| Project | Drawn area | Fixed fee | What sets the fee |
|---|---|---|---|
| Detached new-construction ADU12 sheets × $195 | 400 sq ft | $2,340 | 12 sheets × $195 |
| Garage-to-ADU conversionProject minimum | 600 sq ft | $1,200 | Project minimum |
| Attached ADU additionProject minimum | 750 sq ft | $1,200 | Project minimum |
Sheet counts are confirmed in writing before you approve. Two ADUs on one lot are quoted together, with a credit for work we don't do twice.
What the drawing set includes
An ADU permit set looks like a small house set, plus whatever your city adds for ADUs specifically:
A-0Cover, code and ADU summary
Unit size, height, bedroom count, parking and the local ADU rules the design complies with.
A-1Site plan
Setbacks from every lot line, separation from the main house, utility connections, fire access path and drainage.
A-2Floor plan
Dimensioned layout with egress windows, smoke and CO alarms, and kitchen and bath fixtures.
A-3 / A-4Elevations, sections and roof
Heights measured the way your code measures them, roof pitch, wall and roof assemblies.
S-1Foundation and framing
Prescriptive framing where the code allows it; engineered sheets sealed by your engineer where it doesn't.
E / P / T-24MEP and energy
Electrical and plumbing layouts, and Title 24 or REScheck compliance forms.
What the fee doesn't cover
We'd rather you hear about these now than at plan check. None of them are hidden fees of ours; they're paid to other people, and we tell you up front which ones your project needs.
- Structural engineering
- Detached ADUs in seismic or high-wind areas, and conversions that cut new openings in bearing walls, usually need an engineer. You hire them directly; we draft to their design.
- Soils reports and surveys
- Some cities ask for them on every new detached ADU. Redwood City, California is one we checked in September 2026. We tell you when your city requires them.
- Impact, utility and permit fees
- Paid to the city and utility companies at submittal.
Check your city's ADU limits before anything is drawn
The most expensive ADU mistake we see happens before drafting: a design that's larger than the city allows or sits inside a setback. A 2026 client came to us with a 1,200 sq ft detached ADU for a city whose size cap for their bedroom count was lower. We caught it in the quote reply, before they paid for drawings that would have been rejected.
Cities also differ on paperwork. A 2026 client in Visalia, California told us the city wanted each of the two ADUs on their lot submitted under its own permit application and plan set. We price that as two sets with one shared site base, so the second set costs less than the first.
Questions people ask before they order
How much do ADU plans cost?
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At ArchWorkPro, a new detached ADU under 1,200 sq ft is $195 per sheet, usually 10 to 13 sheets ($1,950 to $2,535). Conversions and attached ADUs are $1 per sq ft of drawn area with a $1,200 minimum.
Do you design the ADU or just draft it?
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Both, within reason. Send a sketch or a plan you like and we lay out the unit to fit your lot and your city's rules, then draw the permit set. We don't provide feasibility studies, financing or builders; we draw.
Can you draw two ADUs on one property?
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Yes. If your city wants separate permit sets, we prepare two and credit the shared work (one site base, one code analysis) so you don't pay for it twice.
Do ADU plans need an architect's stamp?
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In many jurisdictions the architectural sheets for a small residential unit don't need an architect's seal, but the structural sheets often need an engineer's. It varies by state and city, so we check yours when we quote.
How long do ADU plans take?
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A typical ADU permit set takes 5 to 10 business days from the day we have your measurements and site information. Your quote states the date.
Related: Permit sets explained · Garage conversion plans · For owner-builders · Price rules
Get your ADU plans quoted
Send the lot address, a sketch and the size you have in mind. We reply within 2 working hours with a fixed fee, the sheet count and anything in your city's rules that could change the design.
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