Am I allowed to build an ADU on my property?

Short Answer (2025): Probably yes — here’s why

• Colorado’s 2024 ADU law (HB24-1152) requires most Front Range cities to allow one ADU by right on any lot that allows a single-unit detached house, with administrative approval, and generally no owner-occupancy or extra parking mandates (limited exceptions). Effective June 30, 2025. Division of Local Government+1
• Denver adopted Citywide ADUs (effective Dec 16, 2024) so ADUs are allowed across residential areas, still subject to form/design standards. Denvergov+1

Translation: in most Denver-Metro cases, you can build some kind of ADU — the fine print is how big, where on the lot, and with what design rules.

Step 1 — Know the Baseline Rules (State + Denver)

State Baseline (HB24-1152)

• By June 30, 2025, “subject jurisdictions” must:
• Allow one ADU where single-unit homes are allowed (internal, attached, or detached).
• Use an administrative (over-the-counter) approval process.
• Not require additional parking or owner-occupancy (with limited exceptions).
• Apply no stricter design/dimensional standards than those for the primary home.
• Requirements generally extend to PUDs and HOAs inside subject jurisdictions. Division of Local Government

Denver Baseline (2024–2025)

• ADUs allowed citywide (effective Dec 16, 2024). You must still meet ADU form standards in the Denver Zoning Code. Denvergov+1
• Recent updates (2023–2024) reduced barriers, including more flexible bulk plane/height, no minimum lot size, and increased small-lot max floor area up to 864 sq ft (zone/context specific). Axios+2Denver Prelive+2
• A broader 2024 text amendment bundle became effective Feb 25, 2025, which can affect which code version applies depending on submittal date. Denvergov

Step 2 — Confirm Your Property’s Constraints

Quick Eligibility Checklist

• Zoning: You’re in Denver (ADUs allowed citywide), but exact form rules depend on your zone district/context (e.g., Urban/Suburban). Denvergov
• Lot specifics: Verify lot width/area, setbacks, bulk plane, utility easements, alley access, building coverage. (Denver’s ADU background material shows typical small-lot maxes like 864 sf.) Denvergov
• Utilities: Check water (Denver Water SDCs/license) and sewer (SUDP + Metro Water Recovery fees) early; these can influence feasibility and cost. Division of Local Government
• Floodplain/steep slope/trees: Site conditions can constrain placement and foundation type.
• HOA/PUD: State framework limits HOA/PUD restrictions where the jurisdiction is subject to HB24-1152; we still review your covenants to confirm. Division of Local Government

Step 3 — What Size/Height/Placement Can You Build?

Size

• On many smaller Denver lots (≈6,000 sf and under), max ADU floor area commonly ~864 sf (verify your district). Denvergov+1

Height & Massing

• Two-story ADUs are permitted in many area contexts; bulk-plane start relaxed on narrow lots; older 36′ length cap removed in prior text work. Always confirm against your current DZC section. Axios

Placement & Setbacks

• Detached ADUs typically sit toward the rear of the lot; rear setback may be reduced to 0′ on alleys (when no garage door faces the alley) in urban contexts; side setbacks often mirror primary home rules. ArcWest Architects – Denver Architects

We run a one-page “fit study” for your parcel that diagrams the max ADU envelope, entry locations, privacy, and utility routes before you invest in full plans.

Step 4 — Parking, Owner-Occupancy, and Rentals

Parking & Owner-Occupancy

• Under the state framework, extra parking and owner-occupancy requirements are generally not allowed (limited exceptions). Denver’s citywide action aligns with this trend. Division of Local Government

Short-Term vs. Long-Term Rental

• Denver STRs must be at your primary residence and require a license; only one rental contract at a time is allowed. That affects whether an ADU can be a short-term rental for your situation. Denvergov+1

Step 5 — Historic & Design Reviews (If Applicable)

Landmark/Historic Districts

• If your property is a designated landmark or inside a historic district, you’ll need Landmark Preservation design review and a Certificate of Appropriateness before building/zoning permits. The city is updating ADU-specific landmark guidelines (meetings held 2023–2025). Denvergov+1

Typical Historic Considerations

• ADU must respect rear-yard placement, mass/scale, materials, and compatibility with the primary structure and district context. (Example presentation: rear 35% siting guidance.) Denver Prelive

Step 6 — The Fastest Way to Get a Confident Answer

Our 30-Minute Eligibility Screen (Free)

1. Zoning read (district/context + ADU form standards).
2. Envelope sketch (max size/height/setbacks on your lot).
3. Utilities checkpoint (water SDC / SUDP fee path).
4. Special overlays (historic/floodplain/HOA/PUD notes).
5. Go/No-Go & next steps with a rough budget band.

In Denver, the legal landscape is now favorable; feasibility hinges on form standards + site realities. We’ll map those in one call and a simple diagram.