Your Montana Property Has More Potential Than You Think
Everything you need to know about building an ADU in Flathead Valley- zoning, permits, timelines, costs - explained by the ADU builder that families trust most!
What You’ll Learn Inside the 2026 Montana ADU Starter Guide
Building an ADU in Northwest Montana can feel overwhelming when you’re trying to figure out zoning, costs, and timelines on your own. This guide makes everything clear and simple, so you know exactly what to expect before you begin.
Inside, you’ll find:
✔ What’s allowed in Whitefish, Kalispell, Columbia Falls, and Flathead County
✔ How permitting works (and how to avoid delays)
✔ Realistic cost ranges for 2026
✔ A full breakdown of timelines from start to finish
✔ What site prep involves — and how it affects pricing
✔ Common surprises homeowners run into
✔ Big Mountain Cabin Builders’ most popular ADU layouts
✔ The first questions you should ask any builder before you hire them
This guide was created to save you time, stress, and money — and to help you make confident decisions from the very beginning.
Meet the Family Behind Big Mountain Cabin Builders
We’re Madison and Jason — the husband-and-wife team behind Big Mountain Cabin Builders. We raise our four kids just north of Whitefish, and we spend our days building small homes and ADUs for families who love Montana as much as we do.
We’re not a big outfit. We don’t outsource everything. We don’t cut corners. When you work with us, you work with the same people who answer your messages, design your structure, coordinate your build, and deliver it to your property.
We treat every project like it’s our own.
Because in a place like Montana, reputation isn’t a marketing strategy — it’s how you build trust, one home at a time.
Why Homeowners Choose Big Mountain Cabin Builders
When it comes to building an ADU on your Montana property, you want a team who knows the land, understands the codes, and builds with craftsmanship that lasts. We specialize in small structures and ADUs because we believe these spaces should be beautiful, functional, and built with intention — not rushed or pieced together by subcontractors.
When you work with us, you get:
✔ Local expertise — We know the permitting, zoning, and site requirements in Whitefish, Kalispell, Columbia Falls, and the surrounding areas.
✔ A hands-on builder — Jason oversees every build personally. No guessing, no middlemen.
✔ Clear communication — We walk you through the process step-by-step so you always know what to expect.
✔ Quality craftsmanship — Our cabins and ADUs are built to withstand Montana weather and last for generations.
✔ A family who cares — We treat your project like it’s happening in our own backyard.
If you want a builder who actually answers your questions, shows up, and stands by their work, you’re in the right place.
How Your ADU Project Will Work
Building an ADU doesn’t have to feel confusing. Here’s our simple, step-by-step process:
Step 1 — Download the 2026 ADU Guide
This gives you a clear understanding of zoning, timelines, and costs specific to Northwest Montana.
Step 2 — Book a Planning Call
We’ll talk through your goals, budget, property layout, and any possible challenges.
Step 3 — Site Review + Custom Recommendations
We help you choose the right size, layout, style, and location for your ADU.
Step 4 — Permitting & Pre-Build Prep
We guide you through what’s needed and help you stay ahead of potential delays.
Step 5 — Build & Delivery
We construct your ADU with the highest quality materials and craftsmanship, then deliver it to your property.
Simple, clear, and totally doable — even if you’ve never built anything before.
Frequently Asked Questions
Q: How much does an ADU cost in Northwest Montana?
Costs vary depending on size, finishes, and site prep. Most clients invest $60k–$150k+
Q: How long does the process take?
From planning to delivery, most projects take 12–20 weeks, depending on permitting and weather.
Q: Do I need permits?
Sometimes, but not always. If your build falls in city limits, it will require permitting, and each city has different rules. We walk you through exactly what applies to your property.
Q: Do you help with site prep?
Yes — we advise on everything from foundation options to utilities to access routes.
Q: Can I customize my ADU?
Absolutely. Layout, finishes, colors, windows, decks — everything can be tailored to suit your space and lifestyle.
Ready to Explore What’s Possible on Your Property?
Whether you’re trying to create rental income, make space for family, or expand your home’s square footage, an ADU is one of the smartest investments you can make in Northwest Montana.
Start by downloading the free guide — and if you’re ready to talk through your options, we’d love to connect.