Published: 24 Oct 2026 · Last verified: 24 Oct 2026 · Next review: Jan 2027
The most expensive drawing in an ADU project is the first one. Custom ADU plans from a licensed architect run $8,000–$20,000 — before the city has even looked at them. Then plan check adds its own fee and its own months.
Seven cities in our coverage area skip the first cost entirely. They hand you the drawings.
The seven programs
| City | Program | Plans | Cost | Notes |
|---|---|---|---|---|
| Chula Vista | City Standard ADU Plans | 12 | Varies | SnapADU partnership; plan check complete; pairs with $3,951 flat permit |
| Garden Grove | ADU Go | 4 | Free | Four designs, city pre-reviewed |
| Anaheim | ADU Express | 4 | Free | Four designs; most in the series |
| Pasadena | ADU Standard Plans | 4 | 2 free | Prototypes A (374 sq ft) and D (682 sq ft) drawn free by the city; $7,000–$13,000 published permit estimates per plan |
| Fontana | Pre-approved plans | 3 | Free | Includes 738 sq ft design — ducking under the 750 cliff |
| Riverside | Pre-approved ADU plans | Varies | Free | 800 sq ft plans match our benchmark size exactly |
| Sacramento | Pre-approved plans | Varies | Free | 747 sq ft plans — three feet under the cliff, deliberately |
Two patterns stand out. Fontana and Sacramento size their free plans to dodge the 750 sq ft impact-fee cliff — 738 and 747 square feet, respectively. The city is telling you, in floor-plan form, where the fee boundary sits. And Pasadena publishes a permit estimate per plan ($7,000–$13,000), the only city in our series to price its own drawings’ permits in advance.
What “free” actually saves
- Architect fees: $8,000–$20,000. Eliminated if you build the plan as drawn.
- Plan check fees: ~$1,000–$3,000. Pre-approved plans have cleared engineering review; the city typically charges only a reduced site-specific review. (Estimate based on plan-check-as-percentage-of-permit math across the series; confirm with your city.)
- Time: weeks to months. Full plan check cycles run 4–12 weeks per round, with corrections. Pre-approved plans compress this to a completeness check.
What free does not save: the building permit itself (still $1,006–$7,541 depending on city), school fees, impact fees, utility connections, or soils and survey work for your specific lot.
The catches
- No modifications. Pasadena voids pre-approval on structural changes. Most programs allow only site adaptations (foundation type, orientation). Redraw the kitchen and you are back in full plan check.
- Your lot still matters. Setbacks, easements, fire access, and utility locations are site-specific. A free plan that does not fit your lot is not free — it is a starting point you pay an architect to adapt.
- Availability changes. Oceanside runs a pre-approved ADU program whose plan library is currently empty — zero submitted designs. A program on paper is not plans in hand. Confirm the library exists before you plan around it.
- The 750 cliff still applies. A free 800 sq ft plan does not exempt you from impact fees. Only Fontana’s 738 and Sacramento’s 747 thread the needle deliberately.
The bottom line
Free plans are the closest thing to a subsidy most ADU builders will ever touch: $8,000–$20,000 in design fees plus weeks of review, for the cost of building exactly what the city drew. The constraint is the point — the savings come from not changing anything.
Related reading
Free plans cluster just under the 750 line for a reason. Read why that threshold matters, then what the full build costs.