Cost to build accessory dwelling unit — Billings, MT
Last updated: September 24, 2026
What affects the price
Building an ADU is a major project, and the final bill depends on a few key things. Site prep is a big factor; if your land is sloped or needs extensive utility connections, costs go up. The materials you choose—from siding to kitchen finishes—also change the math significantly. Whether you’re building a detached unit or converting an existing garage shifts the permit requirements and structural work needed. We provide exact pricing confirmed free on the call.
About this service
Building an ADU involves costs for permits, site prep, foundation, framing, plumbing, and electrical work. Prices fluctuate based on whether you choose a custom design or a pre-planned layout, as well as the complexity of connecting to existing city utilities. Exact pricing confirmed free on the call.
Frequently asked in Billings
Where can I find an ADU near me in Billings, Montana?
Are there affordable accessory dwelling units available in Billings?
Where can I find accessory dwelling unit services near me in Billings?
What does accessory dwelling unit mean in Billings?
In Billings, an accessory dwelling unit (ADU) means a secondary, independent living space on a single-family lot. This can be a detached structure in the backyard or an attached unit. They offer flexibility for housing family members, guests, or for rental income. It's a way to add living space in Billings.
Are there accessory dwelling unit grants available in Billings?
What is the ADU permit process in Billings?
What are the options for prefabricated accessory dwelling units in Billings?
Also serving nearby: Salt Lake City · West Valley City · Sandy · West Jordan · Fort Collins
More on this: HUD ADU resources — ADU policy and financing research.
Service area details
Serving all of Billings — population 120,864; about 2,652 residents per square mile across 45.6 sq mi. ZIP codes covered include 59101, 59102, 59103, 59104, 59105, 59106, 59107, 59108.
Neighborhoods served in Billings: Downtown Billings, West Billings, South Billings, North Park, Ironwood — and every surrounding area.
Areas we serve
Browse by state, then city.