Do I have to live in Longmont to build an ADU?
✓ Verified against code · August 19, 2026
At application, yes — the city requires proof of Longmont residency (Colorado ID plus two documents like a utility bill or voter registration), waived if the ADU is built with a new home. There's no ongoing live-on-site requirement afterward. Note the state statute's carve-out is written as residency on the parcel; Longmont's city-wide version is a broader reading.
Citation: LMC 15.02.080.E.2
How current is this?
Longmont’s ADU rules run under LMC 15.02.080.E (Longmont Municipal Code) (Ordinance O-2025-35 (amended by O-2025-83)). Longmont adopted its state-compliance rewrite in June 2025 and amended it again in December. Its distinctive features: proof of City of Longmont residency at application (a broader reading than the statute's resides-on-the-parcel check), a total ban on short-term-renting ADUs, and a flat prohibition in the 100-year floodplain. We verified this answer against primary sources on August 19, 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.