How Long Does It Take to Build an ADU in Spokane or North Idaho?
If you’re thinking about adding an accessory dwelling unit (ADU) to your property, you’ve probably already asked the big question:
“How long is this going to take?”
It’s a fair concern — and the answer depends on several moving parts. But when you work with the right team and plan ahead, the ADU process doesn’t have to be a mystery.
At The Building Company, we help homeowners from Spokane to Sandpoint navigate the timeline with clarity, transparency, and efficiency.
Here’s a breakdown of what to expect — and how long it typically takes.
🗓️ The Typical ADU Timeline
While every property and project is different, here’s a general timeline we’ve seen for most ADUs in the Spokane and North Idaho region:
Phase
Feasibility & Site Evaluation
Design & Planning
Permitting & Approvals
Constructio
Typical Duration
1–2 weeks
3–6 weeks
4-10 weeks
3–5 months (weather-dependent)
Total Estimated Time: 4–8 months
(From initial meeting to final inspection)
Let’s unpack what each phase involves.
🔍 Phase 1: Feasibility & Site Evaluation (1–2 Weeks)
This is where we begin. We walk your property, review your goals, and assess:
- Zoning and setbacks
- Lot size and topography
- Access and utility connections
Our job here is to identify what’s possible before you invest in design or permitting.
✏️ Phase 2: Design & Planning (3–6 Weeks)
We work with one of our trusted local designers — or yours — to develop a custom plan for your ADU. During this phase:
- Floor plans and elevations are created
- Finish selections are discussed
- Site plan and utility plans are developed
We also review the design from a construction perspective to avoid costly changes later.
🧾 Phase 3: Permitting & Approvals (4–10 Weeks)
This is where things can get hung up if you’re not working with a seasoned team.
Each jurisdiction — from Spokane County to Kootenai County to cities like Post Falls or Cheney — has its own process and pace.
We handle:
- Permit applications
- Plan corrections and re-submissions
- Utility coordination
- Any specialty reviews (shoreline, historical, etc.)
Our relationships with local departments help keep things moving — but we also plan buffers just in case.
🛠️ Phase 4: Construction (3–5 Months)
Once the permit is issued, construction begins. The timeline depends on:
- Scope and complexity (detached ADUs take longer)
- Site access and utility work
- Weather (especially in winter months)
- Change orders (if you add or alter scope mid-project)
We keep you updated at every stage with weekly communication and milestone check-ins. Our goal:
on time, on budget, no surprises.
👷 What Helps ADU Projects Stay on Track?
- Clear communication from day one
- A realistic, not rushed, schedule
- Experienced subcontractors who know local code
- No shortcuts during design or permitting
At The Building Company, we’ve built ADUs across Spokane Valley, Hayden, Mead, and beyond — and we know where timelines typically stretch or shrink.
Is Now the Right Time to Start?
If you want your ADU ready by next spring or summer, now is the time to start the conversation. Between design, permitting, and contractor schedules, it’s better to plan ahead than rush through critical steps.
We’ll help you map out a timeline based on your goals, your lot, and your lifestyle — with clarity at every step.
📱 Call or text:509-890-0222
📧 Email: info@pnwbuild.com
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The Building Company
is a proud member of NAHB and NARI — committed to clear communication, efficient project delivery, and high-quality ADU construction across the Inland Northwest.
