Are ADUs allowed in Sitka, Alaska?

Yes. Sitka permits accessory dwelling units in residential zones. As an island community with limited developable land, ADUs are an important housing option.

What is the maximum ADU size in Sitka?

Accessory dwelling units in Sitka are generally limited to 800 square feet or 50% of the primary dwelling's floor area, whichever is less.

Are there wetland or terrain restrictions for ADUs in Sitka?

Yes. Sitka has significant wetland areas, steep terrain, and tsunami inundation zones. Development in these areas is restricted or requires special permits.

ADU Rules in Sitka, Alaska | Zoning Guide by Building Club

Sitka is located on Baranof Island in Southeast Alaska and is accessible only by air or water. With constrained developable land and a high cost of living, ADUs are an important housing solution. The City and Borough of Sitka permits ADUs in residential zones under its land use code.

Permitted ADU Types

Detached ADU: A separate structure where lot size and terrain permit
Attached ADU: An addition to the primary home with its own entrance
Conversion ADU: Converting an existing accessory structure to a dwelling unit

Size Limits

ADU Type	Maximum Size
Detached ADU	800 sq ft or 50% of primary dwelling
Attached ADU	50% of primary dwelling floor area
Conversion ADU	Existing footprint

Setbacks

Front: Must comply with base zone standard
Side: 5 feet minimum
Rear: 15–20 feet minimum

Height

Detached ADU: Maximum 25 feet
Cannot exceed height of primary structure

Site Constraints

Sitka has significant development constraints:

Wetlands: Extensive wetland areas — check with Community Development before planning
Steep slopes: Many areas over 25% slope require geotechnical review
Tsunami zones: Low-lying coastal areas have tsunami inundation risk
Rain: Extremely high annual precipitation requires excellent drainage and waterproofing

Seismic Requirements

Sitka is in a high seismic risk area. All structures must comply with Alaska Building Code seismic design requirements.

Parking

One off-street parking space required per ADU where physically feasible.

Permit Process

Site assessment: Check wetland, steep slope, and tsunami zone maps
Zoning check: Confirm eligibility with Sitka Community Development
Submit plans: Architectural and site plans with drainage design
Review: Planning and environmental compliance review
Building permit: Issued by Community Development
Inspections: All required phases
Certificate of Occupancy: Required before occupancy

Contact

City and Borough of Sitka Community Development Department 100 Lincoln Street, Sitka, AK 99835 Phone: (907) 747-1814 Website: cityofsitka.com/government/departments/commdev

Disclaimer: Verify current requirements with the Sitka Community Development Department. Terrain and environmental constraints significantly affect ADU feasibility in many parts of Sitka.

ADU Rules in Sitka, Alaska