Cost to build accessory dwelling unit — Westminster, CO
Last updated: September 24, 2026
What affects the price
Building an ADU involves several moving parts that shape your total budget. The biggest factor is whether you choose a prefabricated unit or a custom build on-site. Site preparation is also significant; if your land requires extensive grading, utility trenching, or foundation work, costs will climb. Your choice of finishes—like kitchen cabinetry, flooring, and siding materials—also shifts the bottom line. We help you navigate these variables to find a setup that fits your property. Exact pricing confirmed free on the call.
About this service
When calculating the budget for a secondary unit, consider the costs for architectural design, permits, materials, and labor. Custom designs and high-end interior finishes will push your budget higher, while standardized layouts can keep costs more predictable. Exact pricing confirmed free on the call.
Frequently asked in Westminster
What's involved in getting an ADU permit in Westminster?
What exactly are accessory dwelling units?
Accessory dwelling units (ADUs) are secondary housing units on a single-family residential lot. They can be attached to the main home or detached, like a backyard cottage. ADUs provide independent living quarters with basic facilities. They offer flexibility for homeowners in Westminster. These units are designed to be fully functional homes.
Are there specific rules for mother-in-law suites in Westminster?
Westminster has regulations for homes with mother-in-law suites, often categorized as ADUs. These rules address size, setbacks, and occupancy. The goal is to ensure they integrate well into existing neighborhoods. They must meet safety and zoning requirements. Consult with a local pro for specific details.
What are the benefits of a backyard accessory dwelling unit?
A backyard ADU in Westminster offers significant advantages. It provides independent living space without compromising your main home's footprint. This unit can serve as rental income, housing for family, or a home office. It adds value to your property. Pros ensure it's designed to complement your existing landscape.
Does Massachusetts have different ADU rules than Westminster?
Yes, Massachusetts has its own state-level ADU legislation and local ordinances that differ from Westminster, Colorado. Regulations regarding size, placement, and permitting vary by state and municipality. Westminster follows Colorado state laws and its own city-specific codes. Always verify local requirements for ADUs.
What is the definition of an accessory dwelling unit?
An accessory dwelling unit, or ADU, is a secondary housing unit on a single-family lot. It's a complete, independent living space. ADUs can be attached or detached from the primary residence. They typically include a kitchen, bathroom, and sleeping area. Their purpose is to provide additional housing options.
What makes a unit an 'accessory dwelling unit'?
A unit is considered an accessory dwelling unit (ADU) when it's a secondary, independent living space on a primary residential lot. It must have its own kitchen and bathroom facilities. ADUs can be newly constructed or converted from existing spaces. They are regulated by local zoning laws. Their purpose is to add housing capacity.
Also serving nearby: Arvada · Thornton · Denver · Lakewood · Boulder
More on this: HUD ADU resources — ADU policy and financing research.
Service area details
Serving all of Westminster — population 114,875; about 3,633 residents per square mile across 31.6 sq mi. ZIP codes covered include 80030, 80031, 80035, 80036.
Neighborhoods served in Westminster: Sheraton, Walnut Creek, Westminster, Westlake, Country Club — and every surrounding area.
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