Adu permit — 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.
Frequently asked in Longmont
What are the general costs associated with accessory dwelling unit construction in Longmont?
The costs for accessory dwelling unit construction in Longmont vary based on size, design, and material choices. Site preparation, utility connections, and permit fees are also factored in. We provide detailed, itemized quotes tailored to your specific project requirements.
What is an ADU unit and how does it work in Longmont?
An ADU unit, or accessory dwelling unit, in Longmont is a secondary housing unit on a single-family residential lot. It can be attached to the primary home or detached. These units must comply with local zoning and building codes to be legally permitted.
What is the best ADU for a property in Longmont?
The best ADU for a property in Longmont depends on your specific needs, lot dimensions, and local regulations. Options include detached backyard units, garage conversions, or basement apartments. We help you determine the most suitable and compliant choice for your site.
What services do you offer for accessory dwelling units in Longmont?
Can I get an accessory dwelling unit for rent in Longmont?
Yes, you can build an accessory dwelling unit for rent in Longmont. ADUs are a popular way to generate rental income while providing additional housing options within the community. We help ensure your unit meets all rental property regulations.
What is the average ADU cost in Longmont?
The average ADU cost in Longmont is project-dependent, influenced by size, complexity, and materials. We provide personalized quotes after a thorough site evaluation and discussion of your specific needs. Contact us for a detailed estimate.
What is involved in ADU construction in Longmont?
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: Westminster, Southmoor, North Longmont, Downtown Longmont, The Peaks — and every surrounding area.
Areas we serve
Browse by state, then city.