{ "license": "ADU Ledger (https://aduledger.com) — CC BY 4.0. Attribution required: link to https://aduledger.com and name \"ADU Ledger\". Verified against primary sources; see /methodology. Not legal advice.", "state": "co", "generated": "2026-08-20", "cities": [ { "slug": "arvada", "name": "Arvada", "state": "co", "county": "Jefferson", "framework": "Land Development Code §5-1-5-2", "ordinance": "2022 LDC (Ord 4793), amended by Ord 4905", "effectiveDate": "2022-03-21", "complianceNote": "Arvada's ADU framework dates to its 2022 code and was amended in August 2025 — after the state deadline — without fixing the provisions that appear to conflict with Colorado's ADU statute: ongoing owner-occupancy with a deed restriction, a blanket parking mandate, and size caps that dip below the statute's protected range. The state's October 2025 compliance review listed Arvada among the non-complying jurisdictions.", "verifiedAt": "2026-08-19", "rules": { "adus": { "v": "One ADU per lot with a single-family detached home, in residential, OT, and MX districts — either Type A (detached) or Type B (interior/attached with separate access), not both.", "cite": "LDC §5-1-5-2.A, .C, .G" }, "size": { "v": "The lesser of 40% of the home's living space and a lot-size tier: 600 sq ft on lots up to 6,000 sq ft; 850 up to 12,499; 1,000 up to an acre; 1,200 beyond. The 600 sq ft tier sits inside the 500–750 sq ft range state law protects — an apparent conflict. In-footprint conversions may reach 50% of the home including basement.", "cite": "LDC §5-1-5-2.E, Table 5-1-5-2; contrast C.R.S. 29-35-402(18)" }, "height": { "v": "25 ft in most RN subdistricts; 30 ft in RN-32.5, R6, R13, R24, and MX districts.", "cite": "LDC Table 2-1-3-3A (rows added by Ord 4905)" }, "setbacks": { "v": "Principal-dwelling standards: RN interior side 5–15 ft, rear 10–15 ft by subdistrict — and zero rear setback where the lot abuts an alley. A detached ADU must sit at or behind the house's front plane (10 ft behind the façade on both frontages of a corner lot).", "cite": "LDC §5-1-5-2.B, .F; Table 2-1-3-3A" }, "parking": { "v": "One on-site space required for the ADU, in addition to the home's parking (tandem allowed) — broader than the narrow case where state law permits requiring a new space.", "cite": "LDC §5-1-5-2.D.1–2; contrast C.R.S. 29-35-403(3)" }, "ownerOcc": { "v": "Still required, ongoing: the owner must occupy the house or the ADU, enforced by a recorded deed restriction that ties the ADU's certificate of occupancy to continued owner occupancy and bars separate sale. State law has barred ongoing owner-occupancy requirements since June 30, 2025; Arvada's August 2025 amendment left this in place.", "cite": "LDC §5-1-5-2.K, .L; contrast C.R.S. 29-35-403(2)(b)" }, "coverage": { "v": "District standards apply (RN lot coverage 25–40% by subdistrict); in the OT district the ADU footprint is capped at the lesser of 800 sq ft or 40% of the house's footprint.", "cite": "LDC §5-1-5-2.B; Table 2-1-5-10B" }, "permit": { "v": "Administrative building permit via eTRAKiT, with a licensed contractor required. Published review timelines — rare and welcome: about 3 weeks for a detached (Type A), 1–2 weeks for an interior/attached (Type B).", "cite": "City ADU page; LDC §3-1-2-1.B" } }, "quirks": [ "ADU utilities must share the home's water and sewer services — no separate taps allowed (the opposite of Everett, WA's separate-meter mandate).", "One short-term rental per property; the ADU may be the licensed STR unit.", "The city's page notes HOA approval — though state law limits HOA ADU bans.", "Closing out the permit takes more than inspections: an improvement location certificate, grading certification, blower-door test, and recorded covenants are all required.", "Arvada is a plaintiff in the six-city home-rule lawsuit — but that case targets other housing laws, not the ADU statute it currently conflicts with." ], "faq": [ { "q": "Is Arvada's ADU code compliant with state law?", "a": "The state says no: Colorado's October 2025 compliance review listed Arvada as non-complying. The specific conflicts: ongoing owner-occupancy enforced by deed restriction, a blanket one-space parking mandate, and a 600 sq ft cap on small lots — inside the 500–750 sq ft range the statute protects. The August 2025 code amendment left all three in place. State law controls on paper, but expect the counter to apply the city's code; get positions in writing.", "cite": "DOLA Oct 2025; LDC §5-1-5-2.D, .E, .K–.L" }, { "q": "How big can an Arvada ADU be?", "a": "It depends on your lot: 600 sq ft on lots up to 6,000 sq ft, stepping up to 1,200 sq ft on lots over an acre — but never more than 40% of the home's living space. Note the small-lot cap conflicts with the state statute's 750 sq ft protection, which is part of the state's non-compliance finding.", "cite": "LDC Table 5-1-5-2" }, { "q": "How long does an Arvada ADU permit take?", "a": "The city publishes targets: about 3 weeks of review for a detached ADU, 1–2 weeks for an interior or attached one — administrative, through the eTRAKiT portal, with a licensed contractor required.", "cite": "City ADU page" }, { "q": "Can my Arvada ADU have its own water meter?", "a": "No — the code requires the ADU to share the principal dwelling's water and sewer services. That cuts utility connection costs but matters for landlords who want separate billing.", "cite": "LDC §5-1-5-2.I" } ], "sources": [ { "label": "LDC §5-1-5-2 (Municode)", "url": "https://library.municode.com/co/arvada/codes/land_development_code" }, { "label": "City ADU page", "url": "https://arvadaco.gov/338/Accessory-Dwelling-Units-ADU" }, { "label": "DOLA ADU program page", "url": "https://dlg.colorado.gov/accessory-dwelling-units" } ], "pending": [ "No corrective ordinance found through August 2026 (the only 2026 LDC amendment covered short-term rentals) — the state-conflict provisions are the top watchlist item.", "The six-city home-rule lawsuit (other statutes) remains pending." ] }, { "slug": "aurora", "name": "Aurora", "state": "co", "county": "Arapahoe / Adams / Douglas", "framework": "UDO §146-3.3.6.G (2018-era rules carried into the 2019 UDO)", "ordinance": "No HB24-1152 compliance ordinance exists", "effectiveDate": "2019-09-21", "complianceNote": "Aurora is the state's highest-profile ADU holdout: its council voted a staff-drafted compliance ordinance down in June 2025, the state formally identified Aurora as non-compliant with the ADU law in October 2025, and as of August 2026 the codified rules are still the restrictive 2018 regime. Where the code conflicts with C.R.S. 29-35-403, state law controls on paper — but the city's counter still applies its own code, and only 9 ADUs have been permitted since 2018.", "verifiedAt": "2026-08-19", "rules": { "adus": { "v": "As codified: one detached ADU per single-family home — attached and internal ADUs prohibited — and only in the Original Aurora MU-OA subdistricts (OA-R1, OA-R2, OA-RMU) on alley-served lots, plus the Painted Prairie master-planned area under its own development plan. State law requires far more; the code hasn't caught up.", "cite": "UDO §146-3.3.6.G.1; Table 3.2-1; contrast C.R.S. 29-35-403(1)" }, "size": { "v": "650 sq ft — below the 750 sq ft the statute protects, one of several provisions in apparent conflict with state law.", "cite": "UDO §146-3.3.6.G.1.h; contrast C.R.S. 29-35-402(18)" }, "height": { "v": "No taller than the principal dwelling, and never more than 24 ft.", "cite": "UDO §146-3.3.6.G.1.i, .p" }, "setbacks": { "v": "Rear yard only; 5 ft side, 5 ft rear, 3 ft from the alley. An ADU atop an existing garage may keep the garage's setbacks.", "cite": "UDO §146-3.3.6.G.1.o; §146-4.2.3.F.1" }, "parking": { "v": "One additional alley-accessed off-street space — and alley service is itself a prerequisite for the use. Both likely exceed what the statute permits.", "cite": "UDO §146-3.3.6.G.1.a, .k; contrast C.R.S. 29-35-403(2)(a), (3)" }, "ownerOcc": { "v": "Still codified: the owner must occupy the primary dwelling or the ADU. Preempted on paper by state law since June 30, 2025, but not repealed.", "cite": "UDO §146-3.3.6.G.1.l; contrast C.R.S. 29-35-403(2)(b)" }, "coverage": { "v": "Lot must exceed 6,000 sq ft; the ADU may cover no more than 50% of the rear yard, and 360 sq ft of usable private open space (minimum dimension 10 ft) must remain.", "cite": "UDO §146-3.3.6.G.1.e, .g" }, "permit": { "v": "Conditional use with a Planning Commission public hearing — the opposite of the administrative approval state law mandates. No published timeline.", "cite": "UDO Table 3.2-1; contrast C.R.S. 29-35-403(1)" } }, "quirks": [ "The numbers tell the story: 9 ADUs permitted (5 built) since 2018, while 262 inquiries between 2023 and mid-2026 fell outside the eligible zones.", "Council rejected the staff-drafted compliance ordinance on June 9, 2025 — the exact tally is contested (press reported 6–2 while admitting the clerk never announced it; a meeting-video summary says 7–2), so we publish the rejection without a number; a July 2026 study session directed staff to draft a broader fix (internal/attached/detached ADUs on most single-family lots, administrative review) — nothing adopted yet.", "Aurora is a plaintiff in the six-city home-rule lawsuit against the state, but that suit targets other housing laws (HB24-1313, HB24-1304, an executive order) — not the ADU statute itself.", "Aurora is not a state-certified ADU-supportive jurisdiction, which affects its access to related state grant programs.", "How the city treats an application citing state law directly (outside the MU-OA zones) is publicly unstated — the city's 2024 memo says existing requirements remain until the UDO is amended." ], "faq": [ { "q": "Can I build an ADU in Aurora?", "a": "Under the city's code as written: only a detached, 650 sq ft ADU on an alley-served lot in the Original Aurora subdistricts, through a public hearing, with the owner living on site. State law (C.R.S. 29-35-403) has required much more since June 30, 2025, and the state formally flagged Aurora as non-compliant in October 2025 — but the code hasn't been amended, so expect friction at the counter and get anything the city tells you in writing.", "cite": "UDO §146-3.3.6.G; DOLA Oct 2025 determination" }, { "q": "Is Aurora breaking Colorado's ADU law?", "a": "The state says yes: Colorado's October 2025 compliance review named Aurora among the jurisdictions not complying with the ADU statute, after its council voted a compliance ordinance down in June 2025. A corrective ordinance was in staff drafting as of July 2026 but nothing has been adopted. We re-check every pass and will log the fix the day it lands.", "cite": "DOLA Oct 7, 2025 release; council record 6/9/2025" }, { "q": "When will Aurora's ADU rules change?", "a": "Unknown — council directed staff in July 2026 to draft an ordinance allowing one internal, attached, or detached ADU on most single-family lots with administrative review, but no ordinance number, hearing date, or adoption exists yet. Any guide describing 'new Aurora ADU rules' before an ordinance passes is ahead of the facts.", "cite": "Council study session 7/13/2026" }, { "q": "Does Aurora's lawsuit against the state cover ADUs?", "a": "No — Aurora joined five other home-rule cities suing over different housing laws (occupancy limits, transit-oriented density, parking) and an executive order. The city is 'not currently fighting' the ADU law in court; it just hasn't complied with it.", "cite": "Six-city suit, Denver District Court (filed 5/19/2025)" } ], "sources": [ { "label": "UDO §146-3.3.6 (codified)", "url": "https://aurora.municipal.codes/UDO/146-3.3.6" }, { "label": "DOLA compliance announcement (Oct 2025)", "url": "https://cdola.colorado.gov/press-release/department-of-local-affairs-dola-announces-high-level-of-local-government-compliance" }, { "label": "Aurora enactment history", "url": "https://aurora.municipal.codes/enactments" } ], "pending": [ "The corrective ordinance directed at the July 13, 2026 study session — this page goes materially stale the day it's adopted; it's the top item on our watchlist.", "The six-city home-rule lawsuit (other housing statutes) remains pending and could reshape the preemption landscape." ] }, { "slug": "boulder", "name": "Boulder", "state": "co", "county": "Boulder", "framework": "B.R.C. 9-6-3(n) (Boulder Revised Code)", "ordinance": "Ordinance 8650 (building on Ord 8571)", "effectiveDate": "2025-03-08", "complianceNote": "Boulder spent two decades as one of the country's most ADU-restrictive cities and unwound it in stages: the per-block saturation caps died in September 2023 (Ord 8571), and owner-occupancy ended March 8, 2025 (Ord 8650). Older Boulder ADU lore — caps, waitlists, owner-occupancy — describes a code that no longer exists, but the size limits remain among the region's tightest.", "verifiedAt": "2026-08-19", "rules": { "adus": { "v": "One ADU per lot — attached or detached, not both — on a lot with one detached home, by right in all zoning districts except RH-6, MH, BMS, BCS, IS-1, and IM.", "cite": "B.R.C. 9-6-3(n)(1)(A)(i); 9-6-1 Table 6-1", "prev": "Per-block saturation caps limited how many ADUs a neighborhood could hold", "changedBy": "Ord 8571, effective Sept 1, 2023" }, "size": { "v": "Attached: the lesser of half the house's floor area or 1,000 sq ft (750 if the house is under 1,500). Detached: 800 sq ft. Affordable ADUs (rent capped at 75% AMI) and designated historic properties get more: attached to 1,200, detached to 1,000. Areas under 6-ft ceilings, mechanical rooms, and below-grade parking don't count.", "cite": "B.R.C. 9-6-3(n)(1)(A)(ii), Table 6-3" }, "height": { "v": "20 ft for a detached ADU; the manager may allow 25 ft with a roof pitch of 8:12 or steeper. Conversions of legal existing accessory buildings may keep their height and roof form.", "cite": "B.R.C. 9-6-3(n)(3)(A)" }, "setbacks": { "v": "Accessory-building setbacks: interior side and rear 3 ft; front 55 ft or behind the house's rear wall; 6 ft of separation from any other building. An attached ADU can extend into the rear setback under conditions (ADU-only space, 5 ft off the rear line, ≤500 sq ft, ≤20 ft tall).", "cite": "B.R.C. 9-7-1 Table 7-1; 9-6-3(n)(2)(B)" }, "parking": { "v": "None — the parking chapter contains no minimum vehicle-parking requirements for ADUs (or anything else; only maximums in two districts).", "cite": "B.R.C. 9-9-6" }, "ownerOcc": { "v": "Not required since March 8, 2025 — the city's page says so explicitly, and no owner-occupancy standard survives in the code.", "cite": "City ADU page; B.R.C. 9-6-3(n) (absence verified)", "prev": "Owner occupancy was required", "changedBy": "Ord 8650, effective Mar 8, 2025" }, "coverage": { "v": "The lot must still meet district FAR and building-coverage limits, and accessory buildings between the house's rear setback and the rear lot line are capped at 500 sq ft of cumulative coverage in the RR/RE/RL/RMX-1 districts.", "cite": "B.R.C. 9-7-1 Table 7-1; 9-7-8(a)" }, "permit": { "v": "Building permit only — the prior administrative-review step was eliminated in September 2023. ADUs in old PUD areas are approved as minor modifications, and prior PUD ADU bans are void. No published timeline.", "cite": "City ADU page; B.R.C. 9-6-3(n)(1)(A)(viii)" } }, "quirks": [ "The affordable-ADU trade: cap the rent at 75% AMI (recorded Declaration of Use) and the size limits jump — 800→1,000 detached, 1,000→1,200 attached.", "Renting either unit requires a City of Boulder rental license, and detached ADU rentals must meet SmartRegs efficiency standards.", "Short-term rental of the ADU or the main house is prohibited (narrow pre-2019 grandfather).", "Detached ADUs need fire sprinklers and an In-Property Wet Utility Permit — real cost lines.", "No separate sale of the ADU; the saturation caps and waitlists of Boulder legend died in September 2023." ], "faq": [ { "q": "Did Boulder really drop its ADU saturation caps and owner-occupancy rule?", "a": "Yes, in stages: the per-block saturation caps ended September 1, 2023, and owner-occupancy ended March 8, 2025 under the state ADU law. If a guide mentions caps, waitlists, or living on site, it's describing the old regime.", "cite": "Ord 8571 (2023); Ord 8650 (2025); city ADU page" }, { "q": "How big can a Boulder detached ADU be?", "a": "800 sq ft — among the tightest detached caps in our Colorado corpus, though Aurora (650 sq ft) and Arvada's smallest-lot tier (600 sq ft) go lower — unless you commit to affordable rent (75% AMI, recorded restriction) or own a designated historic property, which raises it to 1,000 sq ft.", "cite": "B.R.C. 9-6-3(n)(1)(A)(ii), Table 6-3" }, { "q": "Can I Airbnb a Boulder ADU?", "a": "No — short-term rental of either the ADU or the main house on an ADU property is prohibited, with only a narrow pre-February-2019 grandfather. Long-term rentals require a city rental license.", "cite": "B.R.C. 9-6-3(n)(1)(A)(iv); 10-3-19" }, { "q": "Do I need parking for a Boulder ADU?", "a": "No — Boulder's parking chapter sets no vehicle-parking minimums for ADUs at all.", "cite": "B.R.C. 9-9-6" } ], "sources": [ { "label": "City ADU page", "url": "https://bouldercolorado.gov/services/accessory-dwelling-units" }, { "label": "City ADU guide", "url": "https://bouldercolorado.gov/accessory-dwelling-unit-adu-guide" }, { "label": "B.R.C. 9-6-3 (Municode)", "url": "https://library.municode.com/co/boulder/codes/municipal_code" } ], "pending": [ "Ordinance 8745 (2026) re-amended section 9-6-3 as part of a broad Title 9 package; our text reflects the post-8745 codified version, and we characterize 8745's specific changes on the next pass." ] }, { "slug": "colorado-springs", "name": "Colorado Springs", "state": "co", "county": "El Paso", "framework": "UDC 7.3.304E (City Code Ch. 7)", "ordinance": "Ordinance 25-45", "effectiveDate": "2025-04-21", "complianceNote": "Colorado Springs adopted on time — and pushed back on purpose. Council amended the detached-ADU height cap down to 16 ft from the floor, restored a parking requirement staff had proposed eliminating, and wrote into the ordinance's recitals that conflicting state laws 'may be superseded by local law' under home rule, even while seeking supportive-jurisdiction status.", "verifiedAt": "2026-08-19", "rules": { "adus": { "v": "One ADU per lot with a single-family detached home — attached, integrated, or detached — in all districts where single-family homes are allowed. Wildfire (WUI-O) overlay: integrated only; R-2: detached only with a home on a 5,000+ sq ft lot.", "cite": "UDC 7.3.304E.1" }, "size": { "v": "Detached: the lesser of 50% of the principal home's habitable area or 1,250 sq ft; if the home is under 1,500 sq ft, the ADU may still be 750 sq ft. ADU floor area is exempt from the accessory-structure area cap.", "cite": "UDC 7.3.304E.2.a" }, "height": { "v": "16 ft for a detached ADU, regardless of roof type or pitch — council cut this from the prior 25/28-ft standard on the floor. Garage conversions: 25 ft. Attached/integrated: the zone maximum.", "cite": "UDC 7.3.304E.2.b (as amended 3/25/2025)", "prev": "25 ft (28 ft with steep roof) under the prior code", "changedBy": "Ord 25-45 council floor amendment, adopted Apr 8, 2025" }, "setbacks": { "v": "Front and side: same as the principal building. Rear: 5 ft. No detached ADUs in front yards; the old alley/above-garage setback rule was repealed.", "cite": "UDC 7.3.304E.2.c–d" }, "parking": { "v": "One off-street space per ADU, in addition to the home's parking — council restored this after staff proposed zero. Stricter than the state statute's narrow parking allowance.", "cite": "UDC Table 7.4.10-A; contrast C.R.S. 29-35-403(2)(a), (3)" }, "ownerOcc": { "v": "Application-time only: an owner-residency affidavit when applying, with an exception for ADUs built simultaneously with a new home. The old ongoing owner-occupancy and recorded declaration were repealed.", "cite": "UDC 7.3.304E.1.a" }, "coverage": { "v": "ADU exempt from the combined accessory-structure floor-area cap; zone lot-coverage and dimensional tables still apply.", "cite": "UDC 7.3.304E.2.a; Part 7.4.2" }, "permit": { "v": "Administrative — site plan plus building permit, decided on objective standards; utility ability-to-serve determination required, plus a 14-day posted public notice before the permit issues. No land-use application fee. No published review timeline.", "cite": "UDC 7.3.304E.1.i–j" } }, "quirks": [ "An ADU and a short-term rental can't coexist on the same property (grandfathered only if both were legal by June 30, 2025).", "The 16-ft detached height cap is the region's strictest — it effectively rules out two-story DADUs except over converted garages.", "A detached ADU meeting all subdivision provisions may be subdivided and sold — otherwise a recorded no-separate-sale covenant applies.", "Prefab and tiny homes qualify on permanent foundations; the ordinance created a new ADU-O overlay district.", "The ordinance's recitals stake an explicit home-rule position against conflicting state law — making Colorado Springs a jurisdiction to watch if ADU preemption ever reaches the courts." ], "faq": [ { "q": "How tall can a detached ADU be in Colorado Springs?", "a": "16 feet, regardless of roof pitch — city council amended that down from the prior 25/28-ft standard during adoption, over the staff proposal. That's the strictest DADU height cap in our corpus; two-story backyard units are effectively out unless you're converting above a garage (25 ft).", "cite": "UDC 7.3.304E.2.b" }, { "q": "Do I need parking for a Colorado Springs ADU?", "a": "Yes — one off-street space per ADU on top of the home's parking. Staff proposed requiring none; council restored the requirement. It's stricter than what Colorado's ADU statute contemplates, and the city's ordinance openly asserts home-rule authority for such differences.", "cite": "UDC Table 7.4.10-A" }, { "q": "Do I have to live on the property?", "a": "Only when you apply: an owner-residency affidavit at application time (waived when the ADU is built together with a new home). The old ongoing owner-occupancy rule and its recorded declaration were repealed by Ordinance 25-45.", "cite": "UDC 7.3.304E.1.a" }, { "q": "Can I run my Colorado Springs ADU as an Airbnb?", "a": "No — an ADU and a short-term rental can't exist on the same property, unless both were legally permitted before June 30, 2025.", "cite": "UDC 7.3.304.A.3.d" }, { "q": "What does a Colorado Springs ADU permit cost?", "a": "Colorado Springs charges no land-use application fee for an ADU. The permit itself is administrative: a site plan plus a building permit reviewed against objective standards, with a required utility ability-to-serve determination and a 14-day posted public notice before the permit issues. The city has not published a review timeline for this process.", "cite": "UDC 7.3.304E.1.i–j" } ], "sources": [ { "label": "Signed Ordinance 25-45", "url": "https://coloradosprings.gov/system/files/2026-01/Ordinance%2025-45%20Accessory%20Dwelling%20Units.pdf" }, { "label": "City ADU page", "url": "https://coloradosprings.gov/adu" }, { "label": "Council record (CODE-24-0006)", "url": "https://coloradosprings.legistar.com/" } ], "pending": [ "The city's supportive-jurisdiction certification status is unverified; its home-rule recitals make it a candidate for future preemption disputes over the parking and height provisions." ] }, { "slug": "denver", "name": "Denver", "state": "co", "county": "Denver", "framework": "Denver Zoning Code §11.8.2 and Article 3/5 form standards", "ordinance": "CB24-1302 (amended by CB25-0684, CB25-2163)", "effectiveDate": "2024-12-16", "complianceNote": "Denver's citywide ADU ordinance (CB24-1302) ended parcel-by-parcel rezonings in December 2024, a follow-up repealed all vehicle-parking minimums citywide in August 2025, and a February 2026 amendment forced PUDs to allow ADUs. The city's own 2023 'Constructing an ADU' handout, still linked from its permits page, describes the pre-2024 regime — ignore it.", "verifiedAt": "2026-08-19", "rules": { "adus": { "v": "One ADU per primary dwelling unit; in single-unit (SU) districts, one per zone lot, attached or detached. ADUs accessory to two-unit or multi-unit primaries must be detached.", "cite": "DZC §11.8.2.1.A.1–.2", "prev": "ADUs required a parcel-by-parcel rezoning through city council", "changedBy": "CB24-1302, effective Dec 16, 2024" }, "size": { "v": "SU districts: building footprint capped at 864 sq ft on lots of 7,000 sq ft or less, 1,000 sq ft on larger lots — footprint, not floor area, so a two-story unit can roughly double the space. Non-SU attached ADUs: up to the greater of 75% of the primary's floor area or 864 sq ft.", "cite": "DZC §11.8.2.1.B.2; §5.3.4.5" }, "height": { "v": "Urban contexts: 2 stories / 24 ft with a side-lot-line bulk plane (12 ft on lots ≤40 ft wide, then 45°). Suburban: 1 story/17 ft, or 2 stories/24 ft with a 20-ft rear setback. The ADU must sit in the rear 35% (urban) or 50% (suburban) of the lot.", "cite": "DZC §5.3.4.5 form tables" }, "setbacks": { "v": "Urban: side 3 ft (lots ≤40 ft) or 5 ft; rear 5 ft without an alley — with an alley, 5 ft if garage doors face it, 0 ft if they don't. Suburban: side 3/5/7.5 ft by lot width; rear 10 ft (one story) or 20 ft (two). Vehicle access must come from the alley where one exists.", "cite": "DZC §5.3.4.5; §11.8.2.1.C.1" }, "parking": { "v": "None. Denver repealed all minimum vehicle parking requirements citywide effective August 11, 2025.", "cite": "CB25-0684; DZC Div. 10.4", "prev": "Minimum vehicle parking applied per zone", "changedBy": "CB25-0684, effective Aug 11, 2025" }, "ownerOcc": { "v": "No ongoing occupancy requirement. In SU districts, both units must stay under common ownership, and an owner must occupy the primary home at the time of permit application when adding an ADU to an existing house (waived for simultaneous new construction and DHA properties) — the exact carve-out state law allows.", "cite": "DZC §11.8.2.2.A–.B; C.R.S. 29-35-403(2)(b)" }, "coverage": { "v": "A detached ADU counts toward the primary form table's maximum building coverage (Urban House: 60/45/40% by lot width). No ADU-specific bonus.", "cite": "DZC §5.3.4.5; Art. 5 form tables" }, "permit": { "v": "Use by right citywide where single-unit dwellings are allowed — no rezoning since December 2024. Zoning permit + building permit + sewer use & drainage permit; a licensed contractor is required (homeowners can't self-permit). No fixed timeline — the city publishes only a live average-review-times dashboard.", "cite": "CB24-1302; Denver CPD ADU permits page" } }, "quirks": [ "Carriage-lot ADUs are allowed without any primary dwelling — rare anywhere.", "The WDSF+ pilot (Denver Housing Authority / West Denver Renaissance Collaborative) offers design and finance support for income-restricted-rent ADUs, expanded citywide.", "Short-term renting an ADU requires the host to live in the primary structure (Denver's STR primary-residence rule).", "Denver is not on the state's certified ADU-supportive-jurisdiction list, so it doesn't participate in the HB24-1152 fee-reduction grant program.", "A rooftop deck up to 100 sq ft is allowed on alley-adjacent ADUs; no tiny-homes-on-wheels or RVs." ], "faq": [ { "q": "Do I need a rezoning to build an ADU in Denver?", "a": "Not anymore. CB24-1302 made ADUs a use by right citywide wherever single-unit homes are allowed, effective December 16, 2024 — ending the parcel-by-parcel rezoning era. Guides describing the rezoning process, including the city's own older handout, predate the change.", "cite": "CB24-1302; DZC §11.8.2.1" }, { "q": "Do I need parking for a Denver ADU?", "a": "No. Denver repealed minimum vehicle parking citywide effective August 11, 2025 — for ADUs and everything else.", "cite": "CB25-0684" }, { "q": "How big can a Denver ADU be?", "a": "In single-unit districts the cap is a building footprint of 864 sq ft (lots up to 7,000 sq ft) or 1,000 sq ft (larger lots) — and because it's a footprint cap, a two-story ADU can roughly double the livable space within it. Urban-context height allows 2 stories / 24 ft.", "cite": "DZC §11.8.2.1.B.2; §5.3.4.5" }, { "q": "Do I have to live on the property?", "a": "Not on an ongoing basis. In single-unit districts, you must own both units and — when adding an ADU to an existing house — occupy the primary home at the time you apply, which is exactly the carve-out Colorado's ADU statute permits. After that, both units can be rentals (long-term; STR rules differ).", "cite": "DZC §11.8.2.2; C.R.S. 29-35-403(2)(b)" }, { "q": "Does a Denver ADU need a sewer permit?", "a": "Yes — connecting a Denver ADU requires a sewer use and drainage permit in addition to the zoning and building permits. Homeowners cannot pull these permits themselves; a licensed contractor must handle them. Denver does not publish a fixed review timeline for ADU permits, publishing only a live average-review-times dashboard instead.", "cite": "CB24-1302; Denver CPD ADU permits page" } ], "sources": [ { "label": "CB24-1302 (Denver Legistar)", "url": "https://denver.legistar.com/" }, { "label": "DZC Article 11 (use limitations)", "url": "https://denvergov.org/files/assets/public/community-planning-and-development/documents/zoning/denver-zoning-code/denver_zoning_code_article11_use_limitations.pdf" }, { "label": "Denver CPD — ADU permits", "url": "https://www.denvergov.org/Government/Agencies-Departments-Offices/Agencies-Departments-Offices-Directory/Community-Planning-and-Development" } ], "pending": [ "The at-application owner-occupancy rule for existing-house ADUs draws ongoing criticism and is a likely future amendment target; nothing is filed after CB25-2163 (Feb 2026)." ] }, { "slug": "fort-collins", "name": "Fort Collins", "state": "co", "county": "Larimer", "framework": "Land Use Code §3.1.8 and zone-district standards", "ordinance": "Ordinance 009-2025", "effectiveDate": "2025-02-14", "complianceNote": "After the 2022–23 land-use-code repeal saga, Fort Collins re-adopted its code in May 2024 and rewrote the ADU rules for state compliance effective February 14, 2025 (Ordinance 009-2025). The rules are clean and generous; the fees are the story — expect $20,000–25,000 all-in before construction.", "verifiedAt": "2026-08-19", "rules": { "adus": { "v": "One ADU per lot — attached or detached — accessory to a detached house, duplex, triplex, or mobile home, in every zone district since February 2025.", "cite": "LUC §3.1.8; Art. 2 zone tables" }, "size": { "v": "New detached: 750 sq ft if the home is under 1,667 sq ft, otherwise the lesser of 1,000 sq ft or 45% of the home. Converting an existing legal accessory structure: 800 sq ft. Attached: the greater of 750 sq ft or 45% (basement ADUs: up to the full floor).", "cite": "LUC §3.1.8 floor-area tables" }, "height": { "v": "1.5 stories / 28 ft, or the zone standard — Old Town caps at 24 ft or the house's height, whichever is less.", "cite": "LUC §3.1.8; §2.1.6" }, "setbacks": { "v": "At least 5 ft from the house and 10 ft behind its front wall; side and rear per zone (RL example: side 5 ft, rear 15 ft — dropping to 5 ft along an alley).", "cite": "LUC §3.1.8; §2.1.4" }, "parking": { "v": "None for the ADU — only the home's own minimums apply, and a tandem space can count.", "cite": "LUC Div. 5.9; city ADU page" }, "ownerOcc": { "v": "None — no owner-occupancy language anywhere in the code.", "cite": "LUC (verified absence); C.R.S. 29-35-403(2)(b)" }, "coverage": { "v": "ADU floor area is excluded from Old Town's rear-lot floor-area caps and from the RL district's minimum-lot-area ratio — deliberate carve-outs that keep ADUs from eating the lot budget.", "cite": "LUC §2.1.6; §2.1.4" }, "permit": { "v": "Basic Development Review — a staff decision — in every zone, then a building permit; a free conceptual design review is offered first. The BDR flat fee is $6,925, and the city itself pegs typical total fees at $20,000–25,000. No published day-count for review.", "cite": "LUC Div. 4.2; city ADU page" } }, "quirks": [ "The fee reality is the headline: $6,925 flat for review plus impact and utility fees lands most projects at $20,000–25,000 in fees before a shovel turns.", "ADUs permitted on or after January 1, 2024 may not be short-term rentals (earlier licenses grandfathered).", "No new dwelling units in the Poudre River 100-year floodplain.", "The lot under a home and ADU can't be split, but a condo plat is allowed.", "The ADU needs its own electric meter." ], "faq": [ { "q": "What does a Fort Collins ADU permit actually cost?", "a": "More than anywhere nearby: the Basic Development Review flat fee alone is $6,925, and the city's own guidance puts typical total fees — review, impact, utilities — at $20,000–25,000 before construction. Budget for it up front.", "cite": "City ADU page" }, { "q": "Can I build an ADU anywhere in Fort Collins?", "a": "Nearly — since February 2025, ADUs are allowed in every zone district where a house, duplex, or triplex is allowed on the lot, through a staff-level review. The one hard geographic no: the Poudre River 100-year floodplain.", "cite": "LUC Art. 2; §4.3.1(B)" }, { "q": "How big can a Fort Collins ADU be?", "a": "For a new detached unit: 750 sq ft if your home is under 1,667 sq ft, otherwise the lesser of 1,000 sq ft or 45% of the home. Converting an existing outbuilding allows 800 sq ft, and basement ADUs can take the whole floor.", "cite": "LUC §3.1.8" }, { "q": "Can I Airbnb a Fort Collins ADU?", "a": "Not if it was permitted on or after January 1, 2024 — new ADUs can't be short-term rentals; only earlier STR licenses are grandfathered.", "cite": "LUC §4.3.1(B)(1)" } ], "sources": [ { "label": "City ADU page", "url": "https://www.fortcollins.gov/Business/Building-and-Development/Development-Review/Accessory-Dwelling-Units-ADUs" }, { "label": "Land Use Code", "url": "https://www.fortcollins.gov/Government/City-Code-and-Charter/Land-Use-Code" } ], "pending": [ "Land Use Code Phase 2 (commercial corridors and centers) continues through 2026 but hasn't touched ADU standards to date." ] }, { "slug": "greeley", "name": "Greeley", "state": "co", "county": "Weld", "framework": "Greeley Municipal Code Title 24 (Development Code), §24-403", "ordinance": "Ord 35-2021 (ADU section last amended by Ord 7-2023)", "effectiveDate": "2023-02-21", "complianceNote": "Greeley's ADU rules predate Colorado's ADU statute and haven't been amended since February 2023. The code text appears to conflict with C.R.S. 29-35-403 on zones, parking, and size — though notably, the state's October 2025 enforcement review did not list Greeley among non-complying jurisdictions, and the reason is undetermined. Where code and statute conflict, state law controls.", "verifiedAt": "2026-08-19", "rules": { "adus": { "v": "One ADU per lot, with a detached house or duplex/multi-unit building — detached or within the principal building (attic/basement). As codified, permitted only in the R-M, R-H, C-L, C-H, MU-L, and MU-H districts — not in R-E, R-L, or H-A, where single-family homes are permitted, an apparent conflict with the state statute.", "cite": "GMC §24-403.b; Table 24-4-2; contrast C.R.S. 29-35-403(1)" }, "size": { "v": "The lesser of 60% of the home's living area or 1,200 sq ft; a detached ADU is additionally capped as a secondary building at 50% of the home's footprint (up to 1,200 sq ft). On small homes the 60% formula can block ADUs in the 500–750 sq ft range the statute protects.", "cite": "GMC §24-403.b.3; Table 24-5-2; contrast C.R.S. 29-35-402(18)" }, "height": { "v": "25 ft, but no taller than the principal structure — and larger secondary buildings also face a 9-ft wall / 22-ft roof-peak limit.", "cite": "Table 24-5-2; §24-502.c.2" }, "setbacks": { "v": "Side and rear 5 ft; street side 20 ft; at least 12 ft behind the house's front building line and 6 ft from the house. No alley exception.", "cite": "Table 24-5-2; §24-502.c.1" }, "parking": { "v": "As codified: one space per bedroom for a 'secondary dwelling' (the term is undefined; applying it to ADUs is the plain reading), confined to the garage, driveway, or street directly in front — well beyond what the statute permits a city to require.", "cite": "Table 24-7-3; §24-403.b.4; contrast C.R.S. 29-35-403(2)(a), (3)" }, "ownerOcc": { "v": "None — the ADU section contains no owner-occupancy condition.", "cite": "GMC §24-403.b" }, "coverage": { "v": "Greeley uses minimum lot open space per building type rather than a maximum coverage; the detached ADU also lives under the 50%-of-footprint secondary-building cap.", "cite": "Table 24-5-1; §24-503" }, "permit": { "v": "Permitted accessory use — staff review and/or site plan approval, then a building permit via eTRAKiT. Published plan-review times: 20 working days for new construction, 10 for additions and remodels.", "cite": "§24-402.a.1(a); city building-permits page" } }, "quirks": [ "The 'clearly subordinate' standard: the ADU must be visibly secondary and compatible with the main building in design, entrance, and parking placement.", "No ADU-specific short-term-rental ban — unusual on the Front Range.", "Since January 30, 2026, no permits issue in a subdivision until the subdivision or phase is complete.", "The apparent statute conflicts (zones, parking, size formula) have drawn no adopted or visibly pending corrective ordinance — and also no state enforcement listing. A homeowner in R-E, R-L, or H-A is in genuinely uncertain territory: the statute says yes, the code says no." ], "faq": [ { "q": "Can I build an ADU in Greeley's R-L or R-E zones?", "a": "The city's code says no — ADUs aren't a permitted use there even though houses are. Colorado's ADU statute (C.R.S. 29-35-403(1)) says cities must allow them wherever single-family homes are allowed, and state law controls over conflicting local code. Notably, the state's October 2025 enforcement review didn't list Greeley as non-compliant, so how this resolves at the counter is genuinely uncertain — raise the statute, get answers in writing, and expect friction.", "cite": "Table 24-4-2; C.R.S. 29-35-403(1)" }, { "q": "How much parking does a Greeley ADU need?", "a": "The code's table says one space per bedroom — a requirement the state statute almost certainly preempts, since it permits new-space mandates only in a narrow three-condition case. As with the zone question: the code says one thing, the statute another, and no corrective ordinance has been adopted.", "cite": "Table 24-7-3; C.R.S. 29-35-403(3)" }, { "q": "How long does a Greeley permit take?", "a": "The city publishes targets: 20 working days of plan review for new construction, 10 for additions and remodels.", "cite": "City building-permits page" }, { "q": "How big can a Greeley ADU be?", "a": "The lesser of 60% of your home's living area or 1,200 sq ft — and a detached unit is further capped at half the house's footprint. On a small home, that 60% formula can compute below the 500–750 sq ft range state law protects, which is one of the code's apparent statute conflicts.", "cite": "GMC §24-403.b.3" } ], "sources": [ { "label": "GMC Title 24 (Municode)", "url": "https://library.municode.com/co/greeley/codes/municipal_code?nodeId=PTIICOOR_TIT24DECO" }, { "label": "Building permits & review times", "url": "https://greeleyco.gov/business/construction-and-growth/building-permits-and-inspections" }, { "label": "HB24-1152 (signed act)", "url": "https://leg.colorado.gov/sites/default/files/2024a_1152_signed.pdf" } ], "pending": [ "No HB24-1152 corrective amendment found through August 2026 — and, a genuine puzzle, no state non-compliance listing either. We watch both the council record and the state's quarterly compliance reviews." ] }, { "slug": "lakewood", "name": "Lakewood", "state": "co", "county": "Jefferson", "framework": "Zoning Ordinance Title 17, §17.4.3.1 (pre-rewrite code, restored by voter repeal)", "ordinance": "O-2024-12 (the fall-2025 rewrite was repealed by voters April 7, 2026)", "effectiveDate": "2024-07-10", "complianceNote": "Lakewood is the cautionary tale of the Front Range: the city replaced its entire zoning code in fall 2025, the new code was operative for exactly twelve days (January 1–12, 2026) before certified referendum petitions suspended it, and voters repealed all four rewrite ordinances by ~62.5% at an April 7, 2026 special election. The pre-rewrite Title 17 — amended for state ADU compliance in June 2024 (O-2024-12) — governs today, and the city charter bars re-adopting the repealed ordinances until roughly October 2026. Most guides written in late 2025 or early 2026 describe the repealed code.", "verifiedAt": "2026-08-19", "rules": { "adus": { "v": "One ADU per lot, accessory to a single-family home — attached, detached, or over a garage. The old 9,000 sq ft minimum-lot rule was deleted in 2024. Allowed as a limited use in all R districts (and inside the permitted use's building in several mixed/commercial districts); prohibited in the industrial districts.", "cite": "§17.4.3.1.A.1, .3, .8–.11; Table 17.4.1" }, "size": { "v": "1,400 sq ft of gross floor area — the most generous flat cap on the Front Range, raised from 700 sq ft (with a one-bedroom cap, also deleted) by the June 2024 amendment. This generous cap predates the repealed rewrite and survives it.", "cite": "§17.4.3.1.A.6.a (O-2024-12)", "prev": "700 sq ft with a one-bedroom cap", "changedBy": "O-2024-12, adopted June 10, 2024" }, "height": { "v": "The code conflicts with itself: Article 4 says 30 ft, Article 5's table says 20 ft (30 ft over a detached garage). The code's own rule that the more restrictive provision governs makes the effective answer 20 ft, or 30 ft over a garage — but get the city's reading in writing.", "cite": "§17.4.3.1.A.5.b vs. Table 17.5.1; §17.1.6.2.A" }, "setbacks": { "v": "Another internal wrinkle: the ADU section points at primary-structure standards (front 25 / side 15-10-5 / rear 15 ft in R districts), while the accessory-structure table gives 10 ft side/rear in the large-lot districts and 5 ft elsewhere, behind the front edge of the house. Large structures (any wall over 32 ft long or 12 ft high) take primary setbacks. The ADU can't sit in front of the house.", "cite": "§17.4.3.1.A.5; Table 17.5.1; §17.5.5.1" }, "parking": { "v": "Conditional: parking applies only if on-street parking is 'legally or practically unavailable' (arterial/collector frontage, streets under 28 ft, or posted no-parking) — then one space per unit. Since June 30, 2025, the state statute further limits when a new space can be demanded; treat the statute as controlling where more permissive.", "cite": "§17.4.3.1.A.6.e; Table 17.8.1; C.R.S. 29-35-403(3)" }, "ownerOcc": { "v": "Permit-issuance only: an ADU permit issues to an owner-occupant or their designee — no ongoing occupancy requirement and no recorded covenant (the 2024 amendment deleted both). Consistent with the state statute's application-time allowance.", "cite": "§17.4.3.1.A.4 (O-2024-12); C.R.S. 29-35-403(2)(b)" }, "coverage": { "v": "Accessory structures combined: at most 50% of the rear/side/non-primary-front yard area and 10% of the total lot; zone minimum open space runs 25–65% by district.", "cite": "§17.5.5.1.B.1; Table 17.5.1" }, "permit": { "v": "Administrative Review of Supplemental Standards (no hearing, no public input) — and the director must decide within 15 days of a complete application, one of the fastest codified clocks anywhere — plus residential design standards and the building permit.", "cite": "§17.4.3.1.A.7; §17.2.12.2.B.2" } }, "quirks": [ "The repealed rewrite would have kept the 1,400 sq ft cap — the headline number was never actually at stake; the fight was over the rest of the code.", "The 'similar in appearance' design rule (materials, color, roof pitch matching the house) sits in unresolved tension with the state statute's design-standard limits.", "Waivers of ADU standards are possible only through the major-waiver process before the Planning Commission.", "The city charter bars council from re-adopting the repealed ordinances for six months (until about October 7, 2026) — expect a new zoning effort after that.", "Whatever was permitted under the new code during its twelve days in force (January 1–12, 2026) sits in undocumented territory." ], "faq": [ { "q": "Which zoning code is actually in force in Lakewood right now?", "a": "The pre-rewrite Title 17, as amended in June 2024. The fall-2025 replacement code was operative only January 1–12, 2026 — certified referendum petitions suspended it under the charter — and voters repealed all four rewrite ordinances by about 62.5% on April 7, 2026. Guides describing 'Lakewood's new zoning code' are describing repealed law.", "cite": "Charter §13.2(d); April 7, 2026 special election results" }, { "q": "How big can a Lakewood ADU be?", "a": "1,400 sq ft of gross floor area — the most generous flat cap on the Front Range (Thornton's formula, the greater of 1,000 sq ft or 50% of the home's floor area, can run higher on a large house), adopted in June 2024 (up from 700 sq ft with a one-bedroom limit). It predates the repealed rewrite, so the repeal didn't touch it.", "cite": "§17.4.3.1.A.6.a (O-2024-12)" }, { "q": "How tall can a detached Lakewood ADU be?", "a": "The code disagrees with itself — 30 ft in one article, 20 ft (30 over a garage) in another — and its own tie-breaker rule says the more restrictive number governs, so plan on 20 ft (30 over a garage) and get the city's determination in writing before designing taller.", "cite": "§17.4.3.1.A.5.b; Table 17.5.1; §17.1.6.2.A" }, { "q": "How fast is a Lakewood ADU approval?", "a": "The zoning step is unusually fast on paper: an administrative review with no hearing, and the director must decide within 15 days of a complete application. Building-permit review time is separate and unpublished.", "cite": "§17.2.12.2.B.2" }, { "q": "Do I have to live on the property?", "a": "Only at permit issuance — the permit goes to an owner-occupant or their designee. The old ongoing-occupancy rule and its recorded covenant were deleted in the June 2024 state-compliance amendment.", "cite": "§17.4.3.1.A.4" } ], "sources": [ { "label": "Lakewood Zoning Ordinance (current, pre-rewrite Title 17)", "url": "https://www.lakewoodco.gov/Local-Government/Departments/Sustainability-and-Community-Development/Lakewood-Zoning-Ordinance" }, { "label": "April 7, 2026 special election results", "url": "https://www.lakewoodco.gov/Local-Government/Departments/City-Clerks-Office/Elections/April-7-Special-Election" }, { "label": "HB24-1152 (signed act)", "url": "https://leg.colorado.gov/sites/default/files/2024a_1152_signed.pdf" } ], "pending": [ "The charter's six-month re-adoption bar lifts around October 7, 2026 — a new zoning effort is likely after that; this page's framework could change again.", "O-2024-12's exact effective date is pinned to ~July 2024 by charter math; the ordinance PDF itself is bot-blocked (manual download would confirm).", "The internal height and setback contradictions await a city determination; we publish both readings rather than pick one." ] }, { "slug": "longmont", "name": "Longmont", "state": "co", "county": "Boulder / Weld", "framework": "LMC 15.02.080.E (Longmont Municipal Code)", "ordinance": "Ordinance O-2025-35 (amended by O-2025-83)", "effectiveDate": "2025-06-03", "complianceNote": "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.", "verifiedAt": "2026-08-19", "rules": { "adus": { "v": "One ADU per lot, accessory to a single-family detached home only — integrated, attached, or in a detached accessory structure (a garage works). No mobile homes, RVs, or trailers as ADUs.", "cite": "LMC 15.02.080.E.3.a–b" }, "size": { "v": "500–800 sq ft regardless of the home's size — and larger is allowed up to 50% of the home's finished above-ground floor area, so 800 isn't a hard cap on bigger houses. Basement ADUs have no size limit at all.", "cite": "LMC 15.02.080.E.3.b.ii–iv" }, "height": { "v": "A detached ADU may not exceed the height of the principal structure.", "cite": "LMC 15.02.080.E.3.c.i" }, "setbacks": { "v": "Rear 5 ft, side 5 ft; no closer to the front line than the house (corner and multi-frontage lots get flexibility). An ADU inside an existing detached structure keeps its setbacks unless expanded.", "cite": "LMC 15.02.080.E.3.d" }, "parking": { "v": "None required, and no more than two spaces may be provided. (The city's guide describes a statute-shaped one-space exception for lots with no off-street parking and no on-street option — not yet visible in the codified text.)", "cite": "LMC 15.02.080.E.3.f" }, "ownerOcc": { "v": "No ongoing requirement — but the applicant must prove City of Longmont residency at application (Colorado ID plus two supporting documents), waived when the ADU is built together with a new home. Note the statute's carve-out is residency on the parcel; Longmont's city-wide version reads more broadly.", "cite": "LMC 15.02.080.E.2; C.R.S. 29-35-403(2)(b)" }, "coverage": { "v": "All accessory structures combined may not exceed 75% of the home's floor area — which can force removing or shrinking existing sheds and garages to fit an ADU. ADUs are excluded from density calculations.", "cite": "LMC 15.04.040.B.1; 15.03.070.B.3.e" }, "permit": { "v": "Building permit through the Chief Building Official — a five-step checklist process with multi-department plan check. No published timeline; typical city fees run $5,000–$10,000, plus school fees.", "cite": "LMC 15.02.080.E.1; city ADU guide" } }, "quirks": [ "Short-term rental of an ADU is prohibited outright — no rentals under 30 days, ever.", "No ADUs in the 100-year floodplain or floodway, full stop.", "Architectural matching standards apply: matching eaves and colors, corner-lot façade features, and no fluorescent or glossy finishes.", "A 3-ft all-weather sidewalk to the ADU entrance, wayfinding signage, and a separate address are required.", "Post-2025 PUDs can't restrict ADUs beyond the code, and HOAs can't prohibit them (state law)." ], "faq": [ { "q": "How big can a Longmont ADU be?", "a": "The baseline band is 500–800 sq ft — but it's not a hard ceiling: an ADU may exceed 800 sq ft up to half the home's finished above-ground floor area, and basement ADUs have no size limit at all.", "cite": "LMC 15.02.080.E.3.b" }, { "q": "Do I have to live in Longmont to build an ADU?", "a": "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.", "cite": "LMC 15.02.080.E.2" }, { "q": "Can I Airbnb a Longmont ADU?", "a": "No — the code prohibits short-term rental of ADUs entirely; nothing under 30 days.", "cite": "LMC 15.02.080.D" }, { "q": "What will a Longmont ADU permit cost?", "a": "Budget $5,000–$10,000 in city fees (plan review, permit, taxes, community investment fees) plus school district fees — before construction costs. The process is a five-step checklist through the building department.", "cite": "City ADU guide (Jan 2026)" } ], "sources": [ { "label": "LMC 15.02.080 (Municode)", "url": "https://library.municode.com/co/longmont/codes/municipal_code" }, { "label": "City ADU guide (Jan 2026)", "url": "https://longmontcolorado.gov/wp-content/uploads/2026/01/ADU-Guide_January_2026.pdf" }, { "label": "City ADU page", "url": "https://longmontcolorado.gov/planning-and-development-services/development-process/accessory-dwelling-units-adus/" } ], "pending": [ "The city guide's one-space parking exception (statute-shaped) isn't in the codified text — 17 ordinances were pending codification at our last check; we watch for the amendment.", "Whether the city-wide (vs. on-parcel) residency-proof reading draws a state compliance challenge." ] }, { "slug": "pueblo", "name": "Pueblo", "state": "co", "county": "Pueblo", "framework": "PMC 17-4-16 (Pueblo Municipal Code)", "ordinance": "Ordinance 11022", "effectiveDate": "2025-08-25", "complianceNote": "Until August 25, 2025, new ADUs were prohibited in Pueblo entirely — only units 'established' before February 1968 were recognized. The city obtained a six-month compliance extension from the state, then adopted rules that track the statute nearly verbatim. Everything written about Pueblo ADUs before late August 2025 describes a ban.", "verifiedAt": "2026-08-19", "rules": { "adus": { "v": "One ADU — attached, detached, or integrated — accessory to a one-family residence, in any zone district (including PUDs) where one-family residences are allowed. Not permitted on lots with duplexes, townhouses, multi-family, mobile homes, or RVs.", "cite": "PMC 17-4-16(a), (b)(6)" }, "size": { "v": "The lesser of 100% of the residence's gross floor area or 800 sq ft.", "cite": "PMC 17-4-16(b)(7)" }, "height": { "v": "A detached ADU may not exceed the height of the residence on the lot; attached ADUs use the zone maximum (35 ft in most residential districts).", "cite": "PMC 17-4-16(b)(8)" }, "setbacks": { "v": "Rear: 5 ft for ADUs up to 16 ft tall; taller units meet the zone rear setback. Front and side per zone standards.", "cite": "PMC 17-4-16(b)(9)" }, "parking": { "v": "One space only if all three statutory conditions apply (no existing usable off-street space; the zone required parking as of January 1, 2024; the block prohibits on-street parking) — otherwise an existing surplus space is simply designated to the ADU. Statute-verbatim.", "cite": "PMC 17-4-16(b)(10)–(11)" }, "ownerOcc": { "v": "Application-time only: proof of occupancy (a utility or medical bill, first-class mail, or bank statement within 12 months) when applying. No ongoing requirement.", "cite": "PMC 17-4-16(b)(1)" }, "coverage": { "v": "ADUs are exempt from the accessory-building chapter entirely — including its 15%-of-lot / 1,500 sq ft caps. The zone's general lot coverage (50% in most residential districts) still applies.", "cite": "PMC 17-4-23(a)(7); 17-4-2(d)" }, "permit": { "v": "Administrative approval plus a building permit via the regional building department. The state reviewed the draft for statutory compliance before adoption. No published timeline.", "cite": "PMC 17-4-16; TA-22-03 staff packet" } }, "quirks": [ "The distinctive Pueblo requirement: a detached ADU must be color- and material-complementary to the house AND incorporate at least 7 of 17 listed design features — the heaviest design menu in our corpus.", "No separate sale or subdivision of the ADU from the residence.", "Manufactured homes qualify as ADUs on an engineered permanent foundation; mobile homes and RVs don't.", "The legacy pre-1968 'established ADU' category survives as its own classification.", "Between the state deadline (June 30, 2025) and adoption, Pueblo operated under a state-granted extension — a nuance most coverage misses." ], "faq": [ { "q": "Can I build an ADU in Pueblo now?", "a": "Yes — since August 25, 2025. Before that, new ADUs were prohibited citywide (only pre-1968 units were recognized), so anything you read dated earlier describes a ban that no longer exists. One ADU per lot, up to 800 sq ft, by administrative approval.", "cite": "PMC 17-4-16 (Ord 11022)" }, { "q": "What design rules apply to a Pueblo detached ADU?", "a": "The strictest design menu in the region: colors and materials must complement the house, and the unit must incorporate at least 7 of 17 enumerated design features. Budget design time accordingly.", "cite": "PMC 17-4-16(c)" }, { "q": "Do I need parking for a Pueblo ADU?", "a": "Usually not. A new space is required only in the statute's narrow case — no existing usable off-street space, a zone that required parking as of January 1, 2024, and a block where on-street parking is prohibited. Otherwise you just designate an existing surplus space.", "cite": "PMC 17-4-16(b)(10)–(11)" }, { "q": "Was Pueblo late complying with the state ADU law?", "a": "Technically the ordinance passed about eight weeks after the June 30, 2025 deadline — but Pueblo had obtained a six-month compliance extension from the state, so it wasn't a scofflaw. The adopted rules track the statute nearly word for word.", "cite": "Ord 11022; TA-22-03 staff packet" } ], "sources": [ { "label": "Ordinance 11022 (council packet)", "url": "https://www.pueblo.us/DocumentCenter/View/38421/TA-22-03-Staff-Packet" }, { "label": "PMC Title 17 (Municode)", "url": "https://library.municode.com/co/pueblo/codes/code_of_ordinances" } ], "pending": [ "No ADU-specific fee schedule located; fees unverified." ] }, { "slug": "thornton", "name": "Thornton", "state": "co", "county": "Adams", "framework": "Development Code §18-339 (reenacted Chapter 18)", "ordinance": "Ordinance 3742", "effectiveDate": "2025-09-01", "complianceNote": "Thornton reenacted its entire Development Code effective September 1, 2025 — mostly statute-shaped, with one glaring exception: it kept an ongoing owner-occupancy requirement enforced by a recorded deed restriction, which Colorado's ADU statute has barred for cities like Thornton since June 30, 2025. The state's October 2025 compliance review listed Thornton among the non-complying jurisdictions.", "verifiedAt": "2026-08-19", "rules": { "adus": { "v": "One ADU per lot — interior, attached, or detached — accessory to a single-unit detached dwelling, permitted in the RE, RL, RM, RH, AG, and SFD-L districts.", "cite": "Dev. Code §18-339(b),(c),(e); Table 18-334.1" }, "size": { "v": "The greater of 1,000 sq ft or 50% of the home's gross floor area — garages, porches, and similar areas excluded from the calculation. Also exempt from the 5% accessory-use area cap.", "cite": "§18-339(k)(1)–(3)" }, "height": { "v": "Same standards as the principal dwelling 'unless otherwise noted' — and the district tables note a split (e.g., RL: 35 ft for the house and for ADUs above a garage, 16 ft for other accessory structures), leaving ground-level detached ADU height ambiguous between the two numbers. Get the city's reading in writing.", "cite": "§18-339(f); Table 18-76.1 fn 7" }, "setbacks": { "v": "Same as the principal dwelling unless noted. RL example: interior side 5 ft; rear 15 ft principal / 5 ft accessory on front-loaded lots; alley-loaded 10/0 ft (20 ft for an alley garage with driveway).", "cite": "§18-339(f); Table 18-76.1" }, "parking": { "v": "One space per ADU, on the same lot and shown on the development-plan site plan. The statute only allows requiring a new space in a narrow three-condition case; how Thornton applies this is untested.", "cite": "Table 18-650.1; §18-339(h); contrast C.R.S. 29-35-403(3)" }, "ownerOcc": { "v": "Still required, ongoing: the owner of record must occupy either the house or the ADU, and a recorded deed restriction ties the ADU's certificate of occupancy to continued owner occupancy. This directly conflicts with C.R.S. 29-35-403(2)(b), which bars ongoing owner-occupancy requirements for subject jurisdictions — Thornton is one, and the state listed it as non-compliant in October 2025.", "cite": "§18-339(l), (n)(1)(c); DOLA Oct 2025 determination" }, "coverage": { "v": "All accessory buildings combined, ADU included, must stay within the district's maximum lot coverage (RL 85%, RE 45%).", "cite": "§18-336(b)(2); Tables 18-75.1/76.1" }, "permit": { "v": "Administrative development plan (director-approved) plus building permit; the ADU's certificate of occupancy requires the home's CO first, and water/sewer capacity verification is required. Small or non-visible projects (≤500 sq ft, or not visible from the right-of-way) skip the development plan. No published timeline.", "cite": "§18-339(g)–(j); §18-41(b)" } }, "quirks": [ "Maximum one kitchen in the ADU and one in the principal home — an unusual anti-duplex provision.", "Separate exterior entrance and 'Unit 1 / Unit 2' addressing required.", "Short-term renting the ADU is allowed only if the principal home is the owner's primary residence, and not while any part of the principal home is an STR.", "Home occupations are now expressly allowed inside ADUs.", "The reenacted code is otherwise statute-shaped — the owner-occupancy holdover in subsections (l) and (n) is the specific conflict." ], "faq": [ { "q": "Does Thornton still require me to live on the property?", "a": "The code says yes — ongoing owner-occupancy of either unit, enforced by a recorded deed restriction — but Colorado's ADU statute has barred that requirement for cities like Thornton since June 30, 2025, and the state listed Thornton as non-compliant in October 2025. State law controls on paper; in practice, expect the city to apply its code until it's amended. Get the city's position in writing and know the statute exists.", "cite": "§18-339(l), (n)(1)(c); C.R.S. 29-35-403(2)(b)" }, { "q": "How big can a Thornton ADU be?", "a": "Generous: the greater of 1,000 sq ft or half the home's gross floor area, with garages and porches excluded from the math — one of the roomier allowances on the Front Range.", "cite": "§18-339(k)" }, { "q": "How tall can a detached Thornton ADU be?", "a": "Genuinely ambiguous in the current tables: 35 ft clearly covers ADUs above garages, while other accessory structures cap at 16 ft — and a ground-level detached ADU sits between the definitions. Ask the city for a written determination before designing; we track this on our watchlist.", "cite": "Table 18-76.1 fn 7" }, { "q": "Do I need parking for a Thornton ADU?", "a": "The code requires one space per ADU on the lot. Note the statute limits when a city can demand a *new* space — if you already have a driveway spot to designate, raise C.R.S. 29-35-403(3) at the counter.", "cite": "Table 18-650.1" }, { "q": "Does Thornton verify utility capacity for ADUs?", "a": "Yes — Thornton requires water and sewer capacity verification before an ADU can receive its certificate of occupancy, and the ADU's CO cannot issue until the main house's CO is already in place. The zoning step is an administrative development plan reviewed by the director, though small or non-visible projects — 500 square feet or less, or not visible from the right-of-way — skip that development-plan review entirely.", "cite": "§18-339(g)–(j); §18-41(b)" } ], "sources": [ { "label": "2025 Reenacted Development Code (city PDF)", "url": "https://www.thorntonco.gov/media/file/2025_Reenacted_Development_Code" }, { "label": "DOLA compliance announcement (Oct 2025)", "url": "https://cdola.colorado.gov/press-release/department-of-local-affairs-dola-announces-high-level-of-local-government-compliance" } ], "pending": [ "No corrective ordinance for the owner-occupancy conflict found through August 2026 — the only 2026 Chapter 18 amendment was an unrelated affordable-housing fast-track. Top watchlist item.", "The ground-level detached-ADU height ambiguity (16 vs. 35 ft) awaits a city determination." ] }, { "slug": "westminster", "name": "Westminster", "state": "co", "county": "Adams / Jefferson", "framework": "WMC 11-4-19 (Westminster Municipal Code)", "ordinance": "Ordinance 4272 (amended by Ord 4335)", "effectiveDate": "2025-01-01", "complianceNote": "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.", "verifiedAt": "2026-08-19", "rules": { "adus": { "v": "One ADU per lot — interior (basement/attic), attached, or detached — with any single-family detached home, in any zone where such homes are permitted.", "cite": "WMC 11-4-19(B)–(D)" }, "size": { "v": "The lesser of 1,200 sq ft or 50% of the home's gross floor area, minimum 190 sq ft, maximum two bedrooms — and where the home is under 1,500 sq ft, the ADU may still be up to 750 sq ft (codified March 2026 by Ordinance 4335).", "cite": "WMC 11-4-19(H); Ord 4335" }, "height": { "v": "Same maximum height as the principal dwelling on the lot.", "cite": "WMC 11-4-19(G)" }, "setbacks": { "v": "Front and side: same as the principal dwelling (per the applicable PDP/ODP). Rear: the greater of the district's accessory-building setback or 5 ft. No building over easements.", "cite": "WMC 11-4-19(F)" }, "parking": { "v": "None in most cases — the home keeps its own minimum. One new space only if no existing off-street spot could serve the ADU AND on-street parking is prohibited on the block. Statute-verbatim.", "cite": "WMC 11-4-19(I)" }, "ownerOcc": { "v": "None — the city's own FAQ confirms you may live in the ADU and rent out the main house.", "cite": "WMC 11-4-19 (full section); city ADU guide FAQ" }, "coverage": { "v": "The combined footprint of the home and ADU must stay within the principal dwelling's maximum lot coverage; where PUD documents are silent, no maximum applies.", "cite": "WMC 11-4-19(E)" }, "permit": { "v": "Administrative only — staff-approved building permit via the eTRAKiT portal, no public hearing, no ODP amendment, and no HOA approval required. Published staff review timeline: up to 4 weeks.", "cite": "WMC 11-4-19(K)–(N); city ADU guide" } }, "quirks": [ "No impact fees — no park, school, or land-dedication charges on ADUs, unusual for the region.", "Architectural match: 3 of 7 listed elements must match the main house, with a simplified single-criterion variance path.", "Short-term rental of an ADU is allowed with a license.", "Permanent foundation required — no tiny homes on wheels or RVs; engineered plans required.", "The March 2026 small-home fix came at the state's insistence — an example of the compliance-review process actually working." ], "faq": [ { "q": "How big can a Westminster ADU be?", "a": "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.", "cite": "WMC 11-4-19(H); Ord 4335" }, { "q": "How long does a Westminster ADU permit take?", "a": "The city publishes an answer, which is rare: staff review can take up to 4 weeks, fully administrative — no hearing, no ODP amendment, no HOA sign-off required.", "cite": "City ADU guide; WMC 11-4-19(K)" }, { "q": "Does Westminster charge impact fees on ADUs?", "a": "No — no park, school, or land-dedication fees apply to ADUs, which materially changes the budget versus neighboring cities.", "cite": "City ADU guide" }, { "q": "Do I have to live on the property?", "a": "No — there's no owner-occupancy requirement at all, and the city's FAQ explicitly blesses living in the ADU while renting out the main house.", "cite": "WMC 11-4-19; city FAQ" } ], "sources": [ { "label": "WMC 11-4-19 (Municode)", "url": "https://library.municode.com/co/westminster/codes/code_of_ordinances?nodeId=COOR_TITXILADEGRPR_CH4ZO_11-4-19ACDWUN" }, { "label": "City ADU guide (rev. 3/2026)", "url": "https://www.westminsterco.gov/DocumentCenter/View/6290" }, { "label": "Ordinance 4335", "url": "https://www.westminsterco.gov/DocumentCenter/View/6372" } ], "pending": [ "A citywide Unified Development Code rewrite is in drafting — ADU provisions could move or change on adoption; we re-check each pass." ] } ] }