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ADUs · Boise, Idaho

Boise ADUs, designed and built as real homes.

Fortis designs and builds ADUs in Boise, starting with the property itself — whether it can support one, how it fits, and what should happen before design begins.

Check Your Property for an ADUStart a Conversation
Walnut cabinetry and a green glazed tile backsplash in the 25th Street ADU kitchen, with the island and stainless hood to the right.

An ADU is a residential project, not an add-on.

An ADU still has a foundation, structure, utilities, weather, code, and neighbors. It also has to work with a property that already has a home on it.

Fortis approaches ADUs the same way we approach larger residential projects: understand the property first, then align design, budget, and construction around it.

We are based in Boise and build ADUs here, on the lots, alleys, and streets we know.

The ADU journey

Check the property first. Then define, design, budget, and build.

  1. 01

    Understand the Property

    Before anyone draws an ADU, the property has to be understood. Parcept, Fortis Building Co.’s ADU property-intelligence platform, does this for Boise properties.

    Enter your address and Parcept reviews zoning, lot conditions, existing structures, access, and key site constraints, then returns a free preliminary report on whether an ADU may be feasible and what still needs to be verified. Properties worth pursuing can move into a more detailed verification step before any money is spent on design.

    Check Your Property for an ADU

    Free preliminary report for Boise properties.

  2. 02

    Define the ADU

    With the property understood, we define what the ADU is for, how it sits on the lot, how it relates to the main home, and what it needs to cost. Scope is settled before drawings start.

  3. 03

    Design + Budget

    Architecture, engineering, and a working budget are developed together, so the ADU that is drawn is one that can actually be built.

  4. 04

    Build Deliberately

    Clear scopes, active project management, and strong trade relationships guide execution.

Completed project

Counter-height view across the 25th Street ADU kitchen: the white quartz island with four black stools, walnut lower cabinets, and white oak flooring.

25th Street ADU

Boise, IdahoADUCompleted

A completed Fortis ADU on an established Boise property, designed as a true secondary residence rather than an afterthought. The project reflects the same approach we bring to larger homes: understand the site, resolve the constraints, and build it well.

View all work

Thinking about an ADU on your property?

Tell us where you’re starting. It doesn’t need to be fully figured out yet.

Start a ConversationCheck Your Property for an ADU