500 SF school-fee checkpoint
At 500 SF or more, obtain the serving school district’s assessment before permit issuance; a school fee may apply.
Size changes
more than space.
Explore how jurisdiction, square footage, unit count, site constraints, and finish level can affect fees, reviews, consultants, and the preliminary building budget.
01 / Project inputs
Build a preliminary project profile.
Adjust the inputs to see how size and site conditions can change the permit path and budget.
02 / Jurisdiction summary
City of San Diego
Size framework
Up to 1,200 SF, subject to the selected ADU pathway and site standards
Local impact
The first two ADUs on a premises are currently exempt from City Development Impact Fees (DIF). Additional ADUs over 750 SF may trigger DIF. Detached ADUs above 500 SF also enter a different City building-fee category.
Plan opportunity
Review official jurisdiction source ↗City standard-plan and custom paths available
03 / Threshold analysisREVIEW WITHIN WITHIN WITHIN WITHIN
What changes at 750 SF.
750 SF impact-fee checkpoint
At 750 SF or less, state law prohibits local ADU impact fees. Building, plan-check, utility, school, and other service fees can still apply.
1,000 SF design checkpoint
This size remains within the state-protected minimum allowance for a qualifying ADU with two or more bedrooms, subject to the selected statutory pathway.
1,200 SF upper-range checkpoint
Many local programs allow detached ADUs up to 1,200 SF, but the local ordinance and property conditions control.
City of San Diego unit-count checkpoint
The first two proposed ADUs on a premises are currently exempt from City Development Impact Fees regardless of gross floor area.
04 / Preliminary budget
A sourced planning range, not a bid.
The model uses a regional construction baseline, the selected finish level, known site conditions, architectural production, consultant and agency allowances, and contingency. Final cost must be established through property review and contractor pricing.
Regional marketSan Diego–Chula Vista–CarlsbadCurrent modeled construction rate$425 / SFEstimate confidencePreliminary · property not verified
Construction model$318,750
Architectural production$4,500
Consultants + site allowances$9,000
Permit + agency allowance$5,500
Construction contingency$31,875
Expected planning total$369,625
Low
$314,181Expected
$369,625High
$443,550
This range is a budgeting tool. It is not a contractor proposal, guaranteed price, appraisal, or representation of final permit fees. Utility work, access, soils, grading, fire protection, coastal review, finish selections, market conditions, contractor overhead, and profit can materially change the result.$314,181Expected
$369,625High
$443,550
05 / Data behind the estimate
What is recorded—and what is modeled.
Public data establishes regional labor and material movement. Licensed estimating data can localize construction assemblies. Official agency schedules establish listed fees. Site work and completed construction costs remain allowances until the property, consultants, and contractor proposals are reviewed.
Regional labor
Bureau of Labor Statistics (BLS)Published metropolitan wage data for construction occupations
Review source →Material escalation
Federal Reserve Economic Data (FRED)Producer Price Index trends for construction inputs
Review source →Localized assemblies
RSMeans Data ServicesLabor, material, equipment, and square-foot estimating models
Review source →Permit and impact fees
Reviewing jurisdictionPlanning, Building and Safety, Public Works, fire, utility, and impact-fee schedules
Review source →Recorded public data Published government observations such as wages and price indexes.
Commercial connection Licensed localized estimating information; activation requires a data agreement.
Project allowance A planning amount used until an agency invoice, consultant proposal, contractor bid, or completed-project record replaces it.
What this project likely needs next.
Verify zoning, overlays, utility providers, and the legal ADU pathway for the address.
Confirm bedroom count and whether the selected plan fits the available building envelope.
Confirm whether any coastal review applies.
Screen the parcel against current fire-hazard mapping.
Confirm whether survey, grading, drainage, or geotechnical work is required.
Confirm sewer point of connection and utility agency requirements.
Replace planning allowances with written consultant scopes, official fee calculations, and contractor pricing before establishing the final building budget.
Recorded data where available. Clear allowances where it is not.
The threshold engine uses California law, California Department of Housing and Community Development (HCD) guidance, and official jurisdiction resources. Regional labor and escalation references come from published government data. Localized construction assemblies can be connected through a licensed RSMeans data service. Permit fees, utilities, site work, contractor overhead, and final construction pricing remain property-specific.