Adu unit — Longmont, CO
Last updated: September 24, 2026
What affects the price
Building an ADU is a custom project, so costs vary based on your specific choices. Site conditions are the biggest factor; if your land requires significant grading, utility extensions, or foundation work, those expenses add up quickly. Choosing high-end finishes, custom cabinetry, or complex roof lines will also push the budget higher compared to a standard design. Prefabricated units often offer predictable costs, while custom site-built structures allow for more flexibility but can be harder to estimate upfront. Exact pricing confirmed free on the call.
About this service
An ADU is a secondary dwelling on the same lot as a primary residence. People build these to add versatility to their property, whether they need a home office, a gym, or housing for family. Prices are typically influenced by the size of the unit, the complexity of the site, and the interior finishes you select. We can help you determine what fits your budget. Exact pricing confirmed free on the call.
Frequently asked in Longmont
What are the local ADU regulations in Longmont?
What is the typical cost of an ADU in Longmont?
Can you recommend an accessory dwelling unit contractor in San Diego?
Are there accessory dwelling unit builders near me in Longmont?
What are the benefits of adding a backyard accessory dwelling unit?
What is the process for obtaining an ADU permit in Longmont?
What is a prefab ADU and what are its advantages?
A prefab ADU, or prefabricated accessory dwelling unit, is constructed off-site in a factory setting before being transported and assembled on your property. Advantages include potentially faster construction timelines, more predictable costs due to controlled manufacturing, and often higher quality control. This method can also minimize on-site disruption. We can provide quotes for various ADU types. Call us.
Also serving nearby: Boulder · Thornton · Westminster · Arvada · Greeley
More on this: HUD ADU resources — ADU policy and financing research.
Service area details
Serving all of Longmont — population 98,630; about 3,396 residents per square mile across 29.0 sq mi. ZIP codes covered include 80501, 80502, 80503, 80504.
Neighborhoods served in Longmont: Estes Park, Lyons, Mead, Thornton, Westminster, Windsor — and every surrounding area.
Areas we serve
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