ADU Permit
Accessory Dwelling Unit Permit Guide
ADUs usually require zoning review, building permits, utility planning, fire and life-safety review, and inspections from foundation through final approval.
Permit likelihood
Almost always required for detached ADUs, garage apartments, basement apartments, and new independent dwelling units.
Typical permit cost
$1,000-$10,000+ in permit, impact, utility, and review costs depending on location and scope.
Planning timeline
Two to six months is common where plan review, utility review, and zoning checks are required.
Common permit triggers
- Separate kitchen
- Separate entrance
- Detached dwelling
- Rental or long-term occupancy use
Documents to gather before applying
- Site plan
- Architectural plans
- Energy documentation
- Utility and sewer information
- Fire separation details
Inspection sequence to plan around
- Foundation or slab inspection
- Framing and trade rough-ins
- Insulation and fire separation
- Final building and utility inspections
Mistakes that create delays
- Assuming a guest room is not a dwelling unit
- Missing utility capacity questions
- Ignoring parking or owner-occupancy rules
- Starting construction before zoning approval
State and city variation
State ADU laws may limit local restrictions, but city zoning, utility, and building-code review still control the permit.
Contractor questions
- Who is responsible for pulling the permit?
- Will the permit list the full scope of work?
- Which inspections must happen before work is covered?
- Are permit fees, corrections, and reinspection fees included in the quote?
- Will I receive copies of approvals and final inspection records?