Before You Hire / Flagship guide
ADU Builder Comparison Checklist
Compare ADU builder scope, permit responsibilities, utility assumptions, sitework exclusions, timelines, payments, and references.
Method: Official-source research, plain-English synthesis, and parcel-specific verification guidance. Read our editorial standards.
Use this before comparing ADU estimates
Do not compare only the bottom-line number. Compare the scope, assumptions, exclusions, local experience, permit responsibilities, utility responsibilities, sitework, payment schedule, warranty, and communication process.
How to use the checklist
Ask each builder the same questions, write answers in the same format, and flag any estimate that does not clearly separate design, permit, engineering, construction, utilities, sitework, finish level, timeline assumptions, change orders, and inspection handling.
Builder comparison table
Use this checklist before comparing ADU estimates. Fill in Builder A, Builder B, Builder C, and notes as you interview each company.
| Question | Why it matters | Builder A | Builder B | Builder C | Notes |
|---|---|---|---|---|---|
| Local experience | City and county familiarity can affect submittals, corrections, utilities, and schedule assumptions. | ||||
| Design scope | Clarifies whether revisions, site fit, energy forms, and finish assumptions are included. | ||||
| Permit scope | Shows who submits, tracks corrections, attends appointments, and communicates with departments. | ||||
| Engineering scope | Structural, Title 24, energy, grading, drainage, and foundation work may be separate. | ||||
| Construction scope | Separates site-built work, prefab setting, inspections, cleanup, and final closeout. | ||||
| Utility scope | Meters, panels, sewer laterals, water service, trenching, septic, or well work can change cost. | ||||
| Sitework scope | Grading, drainage, retaining walls, access, demolition, trees, and staging are often separate. | ||||
| Payment schedule | Deposits, progress payments, change orders, and lien releases should be written clearly. | ||||
| Warranty and references | Past work, service response, warranty terms, and communication style matter before signing. |
Official sources and research starting points
Use the current official pages below, then confirm the parcel-specific interpretation with the responsible local department.
Frequently Asked Questions
Is there one statewide answer for this issue?
No. California rules create starting points, but parcel-specific local confirmation is required.
Which department should I contact first?
Start with the planning department for the parcel's city or unincorporated county area, then confirm building, utility, environmental health, and fire authority requirements as needed.
Can I rely on this guide instead of contacting local officials?
No. Use this guide to organize questions and documents, then confirm the answer directly with the appropriate local departments before spending money or submitting plans.
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Put This Research to Work
Use the Property Checker to organize the parcel facts and unanswered questions that matter for your next call.
TinyHomeNavigator provides educational information only. Rules vary by parcel, zoning district, city, county, overlay, utility provider, fire authority, and environmental health department. Always confirm directly with the local planning department, building department, environmental health department, fire authority, and utility providers before buying land, designing, permitting, placing, or building any structure.