Can I Build Second Story Addition in Boise, ID? (2026)
Find out if you can build a second story addition in Boise, ID. Rules, permit requirements, costs, and next steps.
Adding a second story in Boise, ID is possible in most zones, subject to height limits and structural permit requirements.
A second story addition is one of the most complex home improvement projects in Boise, ID. It requires a full building permit, structural engineering review, and must comply with the height limits for your zoning district. Unlike a ground-floor addition, a second story changes the roofline and structural load path of your entire home, triggering stricter engineering requirements. In Boise, zone height limits range from varies feet in R-1A zones — verify your zone before planning.
Second Story Addition Rules in Boise
Second Story Addition Rules in Boise: Building permit required: Yes — all second story additions require a permit. Example height limit (R-1A): varies feet. Structural engineering drawings required. Setbacks apply to the full structure height.
Costs & Fees
Contact the local building department for current permit fees. Budget separately for structural engineering.
Next Steps
Next steps for adding a second story in Boise: 1. Hire a structural engineer to assess your existing foundation and framing capacity. 2. Confirm your zone height limit and verify the addition meets all setback requirements. 3. Submit full structural plans and permit application to the local building department. 4. Inspections required at foundation reinforcement, framing, shear panels, and final.
Boise Planning and Development Services — Building Division
Phone: (208) 608-7100 · Verified July 6, 2026 · Source
Website: https://www.cityofboise.org/departments/planning-and-development-services/
Online Permits: https://www.cityofboise.org/departments/planning-and-development-services/
Frequently Asked Questions
Can I build an ADU in Boise?
Yes. Boise allows ADUs (accessory dwelling units) through its local zoning code (City Code Title 11). You can build a detached or attached ADU on most residential lots. Idaho does not have statewide ADU preemption, but Boise has adopted permissive local ADU allowances. Detached ADUs are limited to 1,000 sqft. No owner-occupancy requirement applies. Permits are processed by Boise Planning and Development Services.
Does Boise require a permit for short-term rentals?
Yes. Boise requires a Short-Term Rental License ($125/year) for all Airbnb-style rentals. An annual fire safety inspection is also required. The license number must be displayed on all listing platforms. Airbnb and VRBO collect and remit applicable Idaho state sales tax and local lodging taxes on behalf of hosts.
What are the setbacks in an R-1C zone in Boise?
In an R-1C zone in Boise (standard single-family residential), the setbacks are: 20 ft front, 5 ft each side, and 20 ft rear. ADUs must maintain 5 ft side and 10 ft rear setbacks. Always verify specific parcel setbacks with Boise Planning and Development Services.
Are solar panels required on new homes in Boise?
No. Idaho does not have a solar mandate for residential construction. Solar is voluntary in Boise. Idaho Power serves the Boise area and offers net metering through their Solar PV Program. HOAs have limited ability to prohibit solar installations under Idaho Code Section 55-115.
What makes Boise zoning unique?
Boise is one of the fastest-growing cities in the US and has updated its zoning code to address rapid growth and housing demand. The city has hillside development constraints through the Hillside and Foothill Development Ordinance for properties in the foothills areas. Boise is also notable for its Greenbelt trail system along the Boise River, which creates open space requirements near the river.
Source: Boise Planning and Development Services — Building Division — Building Regulations. Last verified April 5, 2026. View source