Idaho Falls Basement Finishing Guide: Permits & Code (2026)

Updated October 29, 2026. This guide is general information, not legal, engineering or financial advice. Codes and fees change, so confirm with the office named before you start work.

Quick reference

Topic	What to know	Source
Permit	Basement finish permit from the Idaho Falls Building Division, via ETRAKiT or in person	City of Idaho Falls
Plans	Dimensioned floor plan with rooms, windows, doors, stairs, window wells and new or removed walls	City of Idaho Falls
Bearing walls	Beam schedule and design required to remove one	City of Idaho Falls
Inspections	Framing, rough-in, insulation, drywall, finals	City of Idaho Falls
Bedrooms	Any room used for sleeping needs an egress window	City of Idaho Falls
State code	2018 IRC with Idaho amendments (Idaho Residential Code)	Idaho DOPL
Frost depth	30 inches	Idaho Falls Building Dept. design criteria
Contractor registration	Most jobs over $2,000; $300,000 liability minimum	Idaho DOPL
Radon	2 in 5 tested Idaho homes above recommended levels; found in every county	Idaho Dept. of Health and Welfare
Digging	Locate request 2 to 10 business days before excavation	Idaho DOPL damage prevention

How do basement finish permits work in Idaho Falls?

The City of Idaho Falls Building Division lists the documents for a basement finish permit: a completed residential building permit application and a basement floor plan showing dimensions, room names, the location and size of existing and proposed windows, doors, stairs and window wells, and any new walls or existing walls to be removed. If a load-bearing wall, which the city defines as any wall supporting more than its own weight, is coming out, a beam schedule and design are also required. The city encourages uploading documents through ETRAKiT, its online permitting system, and also accepts them at the Building Division office.

What inspections happen?

The city lists these inspections for a basement finish: framing; rough-in electrical, mechanical or plumbing; insulation; drywall; and final building, electrical, plumbing and mechanical. The permit holder must request each inspection and give the inspector access, by phone or through the online system. Since insulation is inspected before drywall, everything that belongs inside the walls has to be done and inspected first.

What code applies?

Idaho adopts building codes statewide through the Division of Occupational and Professional Licenses. Its list of adopted codes shows the 2018 International Residential Code, with Idaho amendments, as the Idaho Residential Code (2020 edition), and the 2018 International Energy Conservation Code with amendments as the Idaho Energy Conservation Code. Ask the Building Division which edition applies on your permit date, since updates are adopted through the legislature.

Basement bedrooms and egress

The city states that any room used for sleeping must have an egress window. Under the IRC, an emergency escape and rescue opening generally needs at least 5.7 square feet of net clear opening (5 square feet for openings at or below grade), at least 24 inches of clear height and 20 inches of clear width, and a sill no more than 44 inches above the floor, with a well and ladder for below-grade windows. Confirm the numbers with the Building Division before ordering windows. Plan every bedroom's window at the start, even if you finish in phases.

Climate, frost and moisture

Idaho Falls sits at about 4,700 feet on the upper Snake River Plain. It averages around 37 inches of snow a year and has recorded a low of 51 degrees below zero. The city's Building Department design criteria set a 30-inch frost depth. For a basement finish, cold foundation walls and rim joists are where condensation shows up, so continuous insulation and air sealing matter. Snowmelt and spring rain are also the best time to see whether a basement stays dry before you finish it.

Radon

The Idaho Department of Health and Welfare says 2 in 5 tested homes across the state have higher-than-recommended radon, that radon has been found in every county, and that the only way to know is to test. A basement finish covers the slab and walls where radon enters, so test first; if mitigation is needed, the pipe can be routed through unfinished space before walls close.

Who can do the work?

Idaho requires anyone doing a construction job over $2,000 in total labor and materials to register as a contractor with DOPL unless an exemption applies. Registration requires proof of at least $300,000 in general liability coverage and proof of workers' compensation coverage or a reason it isn't required, and registered contractors must show their number on contracts and advertising. Homeowners working on their own residence are exempt. Electrical and plumbing work carry their own license requirements, so ask who on the job holds them.

Outside Idaho Falls

Ammon and Iona: separate cities with their own building staff.
Rigby and rural Jefferson County: the county's basement finish help sheet requires compliance with the 2018 IRC, a minimum 15-business-day plan review, a day's notice for inspections, state permits and inspections for mechanical systems, and a flood plain development permit where it applies.
Shelley and Bingham County: city rules in town, county rules outside.
Rural Bonneville County: handled by Bonneville County Planning and Zoning.

What does finishing typically cost?

This site doesn't price jobs; the contractor you're connected with quotes directly. For a rough national picture:

This Old House (2026) estimates about $7 to $23 per square foot to finish a basement.
Angi lists $30 to $75 per square foot to remodel an existing basement, $6,600 to $16,500 for a basement bathroom, and averages of about $8,000 for a wet bar and $12,000 for a home theater.

Those aren't Idaho Falls prices. Locally, the number of bedrooms and egress windows, bathroom plumbing, and any moisture or radon work are what move a quote most.

Questions to ask a basement finishing contractor

What's your Idaho contractor registration number?
Who pulls the permit and schedules each inspection?
How many egress windows does my plan need, and where?
What insulation and air sealing will you use on the foundation walls and rim joist?
Should I test for radon first?
What's warrantied, and for how long?

Common questions

Do I need a permit to finish a basement in Idaho Falls?

Yes. The City of Idaho Falls Building Division issues basement finish permits and inspects framing, rough-ins, insulation, drywall and finals.

What code does Idaho use for basement finishes?

Idaho adopts the 2018 International Residential Code with state amendments, called the Idaho Residential Code (2020 edition).

Does a basement contractor need to be registered in Idaho?

For most jobs over $2,000, yes. Idaho DOPL handles contractor registration, which requires at least $300,000 in general liability coverage.

Idaho Falls basement finishing guide (2026)