Accessory Structures in Matanuska-Susitna Borough, AK (2026)
2 rules for unincorporated Matanuska-Susitna Borough, Alaska.
Verified from official government sources
ADU Rules
Homeowners in the borough's Single-Family Residential Land Use Districts, Canoe Lake Subdivision, Chugach View Estates and Wilderness East Subdivision, may add up to two accessory dwelling units for guests, family or care providers, capped at a combined 50 percent of the principal dwelling's floor area, under § 17.75.060(B)(5). An ADU can sit inside the house, in a garage apartment, or as its own structure.
Mat-Su SFR District Accessory Dwelling Unit Rule
Some RestrictionsMatanuska-Susitna Borough Code § 17.75.060(B)(5)
Two accessory dwelling units designed and used for guests, family members, or persons providing domestic or health services to the residents of the principal structure on the same lot. The total combined floor area of the accessory dwelling units may not exceed 50 percent of the principal dwelling unit floor area. The accessory dwelling unit may be located within the principal dwelling structur...
Shed & Carport Rules
A shed, detached garage, barn or other storage building in the borough's Single-Family Residential Land Use Districts, Canoe Lake Subdivision, Chugach View Estates and Wilderness East Subdivision, is a permitted accessory use, but all accessory structures combined cannot exceed 150 percent of the principal dwelling's square footage under §§ 17.75.060(B)(1) and 17.75.150(B). Setbacks follow MSB Chapter 17.55.
Mat-Su SFR District Accessory Building Footprint Cap
Some RestrictionsMatanuska-Susitna Borough Code § 17.75.060(B)(1), § 17.75.150(B)
Noncommercial garages attached or detached, storage buildings, barns, fences, and other incidental structures and uses, the total square footage of which all accessory uses shall not exceed 150 percent of the principal dwelling; ... Accessory building uses, whether attached or detached to the principal dwelling, must not have a larger footprint than 150 percent of the principal dwelling.
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