How many ADUs can I build in Bellingham?
✓ Verified against code · August 20, 2026
Two per lot, in any combination you like. The code is explicit that no more than two are permitted alongside the principal unit and that they may be in any configuration of attached or detached units — so two detached ADUs on one lot is allowed, as is one of each.
Citation: BMC 20.10.036(F)
How current is this?
Bellingham’s ADU rules run under BMC 20.10.036 (Accessory Dwelling Units) (Ordinance 2025-12-035 §2). Bellingham completed its HB 1337 alignment in Ordinance 2025-12-035, effective December 23, 2025 — roughly six months after the state's June 30 deadline. Two of the standards below rest on interim ordinances rather than permanent code: the citywide elimination of parking minimums, and the companion infill regulations that sunset in December 2026. We verified this answer against primary sources on August 20, 2026, and every change we catch is logged in the changelog.
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Not legal advice — lot-specific overlays can change the answer for your parcel. The citation above points at the governing code section; check it, or ask the city to confirm.