Guide · Permits & zoning
Denver ADU permits in 2026: the complete rules
LAST VERIFIED: AUGUST 2026 · PRIMARY SOURCES: DENVER CPD, DENVER ZONING CODE, COLORADO HB 24-1152 (C.R.S. 29-35-401–405)
Can I build an ADU on my lot?
Almost certainly yes. Two changes opened the city up: Denver's citywide zoning amendment allowing ADUs in all residential zone districts, and Colorado's HB 24-1152 (compliance required by mid-2025), which requires every sizable Colorado municipality to allow at least one ADU per single-family lot by right, with administrative approval, no minimum lot size games, and limits on parking mandates. HOAs in Colorado can no longer ban ADUs outright.
Verify your specific situation in ten minutes: find your zone district on the Denver zoning map (maps.denvergov.org), then check the detached accessory building standards for that district. Two overlays that add steps: historic districts (Wash Park edges, parts of Capitol Hill, Country Club and others) require landmark review, which adds roughly 2–4 months and design-matching requirements; and HOA covenants, which can still regulate appearance and materials even where they can't prohibit the unit.
Size, height, and placement limits
| Standard | Rule |
|---|---|
| Max size, lot < 6,000 sq ft | 650 sq ft |
| Max size, lot 6,000–7,000 sq ft | 864 sq ft |
| Max size, lot > 7,000 sq ft | 1,000 sq ft |
| Max height / stories | 24 ft / 1.5 stories |
| Placement | Rear 35% of the zone lot depth |
| Rear setback (one-story) | 5 ft typical; varies by zone and alley access |
| Parking | None required for the ADU (per HB 24-1152) |
| Lot coverage / bulk plane | Zone-specific caps apply; ADU counts toward totals |
Two rules trip up more projects than any others. First, bulk-plane geometry — Denver constrains the building envelope with an angled plane from the property line, which shapes what a 1.5-story unit can look like near a neighbor. Second, garage conversions that remove existing required parking for the main house can trigger a compensation requirement. Both are solvable at design stage and expensive to discover at review stage.
What permits does a Denver ADU need?
- Zoning permit — confirms size, height, and placement comply with your zone district's standards.
- Building permit (residential construction) — full plan review of structure, life safety, energy code. Requires architectural drawings, site plan, and structural sheets.
- SUDP (Sewer Use and Drainage Permit) — Denver-specific and easy to miss in budgets: covers the ADU's wastewater and stormwater connections. Denver Water separately charges a System Development Charge for the new unit (see the cost guide for current figures).
Applications go through Denver CPD's online e-permits portal. Under HB 24-1152 the review is ministerial — administrative sign-off against written standards, no discretionary design review, no neighborhood hearing for a compliant application.
How long does it take?
| Stage | Duration |
|---|---|
| Feasibility + design + engineering | 1–3 months |
| CPD plan review (standard ADU) | 4–8 weeks |
| Historic district landmark review (if applicable) | +2–4 months |
| Construction | 4–10 months |
| Application to move-in, all-in | ≈ 7–14 months |
The single biggest controllable factor is submission quality: incomplete or non-compliant plan sets trigger resubmittal cycles that add weeks each round. This is the strongest practical argument for using a builder or designer who has already permitted ADUs in Denver specifically — see how to vet one.
Owner-occupancy and rental rules
Long-term rental (30+ days): no owner-occupancy requirement — Denver removed it in December 2024 (CB24-1303), so both the main house and the ADU can be rented to long-term tenants, and no rental license is required for the ADU itself.
Short-term rental (under 30 days): requires a Denver STR license (~$250/year), and the property must be the host's primary residence — pure-investment Airbnb ADUs are not permitted in Denver.