Setbacks & Height Limits in Boise

This guide explains the basic setback and height rules that apply to residential construction in Boise, Idaho. These numbers depend on your exact zoning district, overlay zones, and lot geometry, so always confirm with Boise Planning and Development Services before finalizing plans.

New Zoning Code (Dec 2023)

Boise adopted a modernized Zoning Code that became effective in December 2023, replacing the prior code that had accumulated decades of amendments. The new Title 11 reorganized residential districts (R-1A, R-1B, R-1C, R-2, R-3), simplified dimensional standards into clearer tables, and lowered barriers for missing middle housing, ADUs, and infill development. If you are working from older guides or permit examples, the setback and height numbers may have shifted — always reference the current code.

What Are Setbacks?

A setback is the minimum required distance between a building and a lot line. Setbacks are measured from the property line to the nearest point of the building (typically the wall, but eaves, bay windows, and chimneys can have their own rules).

Boise's zoning code specifies front, side, and rear setbacks separately for each district. Corner lots have two "front" setbacks (one per street frontage) plus one interior side and one rear.

Typical Residential Setbacks

For Boise's most common single-family residential zones under the post-2023 code:

These are typical base values — your specific lot, overlay, or frontage type may modify them. Higher-density R-3 zones, mixed-use districts, and downtown form-based zones follow separate schedules.

Height Limits

Maximum building height in Boise's R-1A, R-1B, R-1C, and R-2 residential zones is typically 35 ft, measured from average grade to the highest point of the roof (or a defined reference plane for pitched roofs).

Height rules get more restrictive in:

• Boise Foothills / hillside areas — height is measured from existing grade with additional massing limits to protect views and reduce grading
• Historic districts (North End, Hyde Park, Harrison Boulevard, etc.) — context-sensitive height caps apply
• Airport influence area — FAA/airport overlay limits apply near the Boise Airport
• Downtown and mixed-use zones — generally allow greater height, often tied to floor area ratio

Lot Coverage and FAR

Beyond setbacks and height, two other numbers shape how much you can build:

• Lot coverage — the percentage of the lot covered by buildings. Boise residential zones typically allow around 40–50% coverage depending on the district.
• Floor Area Ratio (FAR) — the ratio of total floor area to lot area. A FAR of 0.5 on a 7,000 sq ft lot allows 3,500 sq ft of floor area.

The 2023 code applies FAR primarily in higher-density and mixed-use districts; most base single-family zones rely on coverage plus setbacks and height to regulate bulk.

Common Exceptions and Encroachments

Boise's code allows certain features to project into required setbacks. Typical allowances include:

• Eaves and gutters (usually up to 2 ft)
• Chimneys (up to 2 ft)
• Uncovered porches, stoops, and steps
• Air conditioning condensers (subject to sound limits)
• Bay windows (limited projection)

Fences, retaining walls, and accessory structures have separate rules — check Title 11's accessory structure section.

State ADU Overrides

If your project is an Accessory Dwelling Unit (ADU), Boise's city code — not state law — governs setbacks and height. Idaho does not have a statewide ADU preemption law, so Boise sets its own standards (800 sq ft, 25 ft height, 5 ft rear and side setbacks). See the ADU rules page for this city.

How to Look Up Your Specific Requirements

1. Find your zoning district — use Boise's Open Data portal at opendata.cityofboise.org
2. Read the district regulations — your zone chapter in Title 11 lists setbacks, height, lot coverage, and FAR
3. Check for overlays — Foothills, historic districts, airport influence, and floodplain can modify the base rules
4. Ask planning staff — Boise Planning and Development Services offers zoning verifications and pre-application meetings at (208) 384-3830

Variances

If your project cannot meet the strict letter of the zoning code, you may apply for a variance — a formal request to deviate from the rules based on hardship specific to your lot. Variances are discretionary and require public hearings before the Planning and Zoning Commission. See the Variance Application Guide for the general process.

Official Sources

See the sources linked in the frontmatter for Boise's Title 11 Zoning Code and Planning and Development Services. This guide is informational and is not a substitute for direct confirmation from planning staff.