Build an ADU in Broomfield — Often More Affordably Than Elsewhere
Broomfield’s ADU rules include a feature that can make building here more affordable than in most metro markets: ADUs tie into your main home’s shared utilities. PrimeStone Construction Group is a structural engineer–owned ADU builder navigating Broomfield’s specific requirements — including the cladding-match rule and Declaration of Use — from feasibility to certificate of occupancy.
How much does an ADU cost in Broomfield? ADUs in Broomfield typically run $150,000–$350,000+ (typical detached $230,000–$310,000), and take 4 to 8 months. Broomfield’s shared-utility rule can save meaningfully versus separate utility taps elsewhere.
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Why Broomfield Homeowners Choose PrimeStone for ADU Construction
- Structural engineer–owned: We engineer ADUs to fit Broomfield’s setback and design rules and your lot.
- Broomfield rule expertise: We handle the cladding-match requirement and Declaration of Use recording that Broomfield uniquely requires.
- Shared-utility savings: Broomfield ADUs tie into the main home’s utilities — often cheaper than markets requiring separate taps.
- Single combined authority: All permitting runs through Broomfield Community Development; we manage it end to end.
Broomfield’s ADU Rules — What Makes Them Different
Broomfield is one of Colorado’s few combined city-and-county governments, and it permits one ADU per single-family lot. Broomfield’s rules have some distinctive requirements that we manage for you:
- Size: No more than 50% of the principal home’s footprint, or 800 sq ft, whichever is smaller.
- Setbacks: Typically a minimum 5-foot setback from rear and side property lines for detached ADUs.
- No owner-occupancy: Broomfield does not require you to live on-site (aligned with state law); long-term rental is fully permitted.
- Design match: The ADU must be clad in material similar to the main home.
- Declaration of Use: Detached ADUs require a Declaration of Use recorded against the property title before a Certificate of Occupancy.
- Shared utilities: ADUs tie into the principal home’s water and sewer — a meaningful cost saving.
ADU Cost in Broomfield
ADUs in Broomfield typically run $150,000–$350,000+ (typical detached $230,000–$310,000). Broomfield’s shared-utility rule can save on the order of $10,000–$30,000 versus markets that require separate water and sewer taps, making Broomfield one of the more cost-effective metro markets to build an ADU.
Permits for ADU Construction in Broomfield
ADU construction in Broomfield runs through Broomfield Community Development (the combined city-county authority), requiring building, electrical, plumbing, and mechanical permits, plus a recorded Declaration of Use for detached ADUs before occupancy. A licensed contractor is required. We manage the full process.
Broomfield ADU rules (footprint %, setbacks, Declaration of Use, cladding match) change. PrimeStone confirms current requirements with Broomfield Community Development for every ADU.
Full ADU Construction Details
This page focuses on adu construction specifically in Broomfield. For our complete breakdown of process, costs, timelines, materials, and code requirements, see our main ADU Construction page (linked here).
Frequently Asked Questions
How much does it cost to build an ADU in Broomfield?
ADUs in Broomfield typically run $150,000–$350,000+ (typical detached $230,000–$310,000). Broomfield’s shared-utility rule can save $10,000–$30,000 versus markets requiring separate taps.
What are Broomfield’s ADU size limits?
A Broomfield ADU can be no more than 50% of the principal home’s footprint, or 800 sq ft, whichever is smaller, with a minimum 5-foot setback from rear and side lines for detached units.
Do I have to live on-site to build an ADU in Broomfield?
No. Broomfield does not require owner-occupancy (aligned with Colorado state law), and long-term rental is fully permitted. Short-term rental is constrained by Broomfield’s principal-residence STR rules.
What is a Declaration of Use?
Broomfield requires a Declaration of Use recorded against your property title for detached ADUs before a Certificate of Occupancy is issued. We handle this step as part of the process.
Why are ADUs cheaper to build in Broomfield?
Broomfield ADUs tie into the main home’s shared water and sewer rather than requiring separate taps, which can save $10,000–$30,000 versus other Colorado markets.
Ready to Start Your Broomfield ADU Construction Project?
Ready to build an ADU in Broomfield? PrimeStone’s structural engineer–owned team navigates Broomfield’s rules and delivers your ADU from feasibility to certificate of occupancy.
Get a Free Consultation → 720-468-0686 · info@primestonecg.com