How big can a Westminster ADU be?
✓ Verified against code · August 19, 2026
The lesser of 1,200 sq ft or half the home's floor area, with two protections: a 190 sq ft minimum, and — since March 2026 — a guarantee that owners of homes under 1,500 sq ft can still build up to 750 sq ft. Maximum two bedrooms.
Citation: WMC 11-4-19(H); Ord 4335
How current is this?
Westminster’s ADU rules run under WMC 11-4-19 (Westminster Municipal Code) (Ordinance 4272 (amended by Ord 4335)). Westminster complied six months early (January 1, 2025) with clean, statute-shaped rules — then amended once more in March 2026 (Ordinance 4335, at the state's insistence) to guarantee small-home owners the statutory 750 sq ft. One of the smoothest adoptions on the Front Range, with a published review timeline to match. We verified this answer against primary sources on August 19, 2026, and every change we catch is logged in the changelog.
More Westminster ADU questions
- How long does a Westminster ADU permit take?
- Does Westminster charge impact fees on ADUs?
- Do I have to live on the property?
All Westminster ADU rules → · Compare Colorado cities →
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.