ADU Rules in Sitka, Alaska

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

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

1. Site assessment: Check wetland, steep slope, and tsunami zone maps
2. Zoning check: Confirm eligibility with Sitka Community Development
3. Submit plans: Architectural and site plans with drainage design
4. Review: Planning and environmental compliance review
5. Building permit: Issued by Community Development
6. Inspections: All required phases
7. 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.