ADU builder in Boise's East End

It depends on the exact street. Parcels on Warm Springs Avenue or within the East End Historic District boundary fall under HPC review for any ADU construction. Outer East End parcels closer to the foothills are typically outside the historic overlay but may sit inside the Hillside Development Overlay if the slope exceeds 15%. The Ada County parcel viewer and the city's Planning + Development Services counter confirm which overlay (if any) applies to your specific address — we pull that data on the free lot check.

Geothermal service is a unique East End feature for the primary residence, but a new detached ADU is typically permitted and built with conventional gas or electric heat. Tapping into the geothermal system requires coordination with the Boise Warm Springs Water District and is a separate, optional scope item. Most ADU pro-formas on Warm Springs parcels are built around conventional HVAC for predictable cost.

Yes, in most cases. The historic two-lot purchase pattern yielded effective 50 ft × 122 ft parcels around 6,100 sq ft, which is above Boise's 5,000 sq ft minimum lot for an ADU and accommodates the smaller pre-approved plans cleanly. Original single 25-ft lots are too narrow for a detached unit without variances, and parcels split awkwardly between two owners can have non-conforming lot geometry — both confirmable on the parcel record before any bid.

Only if the slope across your proposed ADU footprint exceeds 15%. Boise's Hillside Development Overlay (HS-O) uses 15% as the trigger and breaks projects into three categories: Category 1 (planning director approval, minor work on prepared pads), Category 2 (moderate grading, retaining walls > 4 ft, driveways > 100 ft or > 15% grade), and Category 3 (major grading or slope-stability concerns). Most foothill-edge East End ADUs that need HS-O review land in Category 1 or Category 2.

Yes. Boise's 2023 Modern Zoning Code cap of 900 sq ft or 50% of the primary dwelling, whichever is less, applies across the East End. On larger Warm Springs primaries the 900 sq ft hard cap controls; on smaller historic cottages the 50% rule usually becomes the binding constraint.

Construction is performed by our licensed builder partner, Iron Crest Remodel (Idaho RCE-6681702), under the BoiseADU.com pre-approved-plan program. Same fixed-price contract, same Boise-based crews, same lot check before any bid.