Legal basement bedrooms in Idaho Falls
What it takes for a basement room to count as a bedroom: a way out, the right alarms and a permit.
A legal basement bedroom in Idaho Falls is a sleeping room with an egress window or exterior door that meets the residential code, working smoke and carbon monoxide alarms, and a permit and inspections from the city. This page is for families adding bedrooms for kids, owners renting out basement rooms, and sellers who want an accurate bedroom count. The result is a room someone can safely sleep in and escape from.
What makes it legal
- Egress. The City of Idaho Falls says any room used for sleeping must have an egress window. Under the International Residential Code that Idaho adopts, the opening generally needs 5.7 square feet of net clear area (5 square feet at or below grade), at least 24 inches of clear height, 20 inches of clear width, and a sill no higher than 44 inches. Confirm the exact numbers with the Building Division.
- A window well. Below-grade windows need a well large enough to climb out of, with a ladder or steps when it's deep. The city's permit floor plan must show window wells.
- Alarms. Smoke alarms in and outside sleeping rooms and carbon monoxide protection where the code calls for it.
- The permit. The bedroom is part of the basement finish permit and is inspected with it.
Signs a room isn't a legal bedroom
- The window is small, high or doesn't open far
- The well is shallow, too narrow or missing a ladder
- No smoke alarm inside the room
- The room was finished without a permit
Why it's so common here
Bonneville County's cities have grown fast, and households here skew young. In Iona, for example, the 2020 census put the median age at 29.5, with 38.3 percent of residents under 18. Many families buy a home with an unfinished basement and add bedrooms one at a time. Each new bedroom needs its own egress. Ask the contractor to plan window locations for the whole basement at once, even if you finish in phases.
Before anyone digs
Idaho's damage prevention rules call for a locate request at least 2 and no more than 10 business days before excavation. The contractor usually files it. Private lines, such as sprinkler lines or power to a shop, aren't marked by utilities and need a private locator.
What affects the cost?
- Cutting a new opening versus enlarging an existing window
- Poured concrete or block walls
- Well depth, material, ladder and cover
- Alarm wiring, closet and door work
Where we can connect you
Common questions
Does every basement bedroom need its own egress window?
Yes. The City of Idaho Falls says any room used for sleeping must have an egress window.
Can a basement bedroom share a window well with another room?
Each bedroom needs its own escape opening. Windows can sometimes be placed so wells are close together, but each room needs its own way out.
Do I need a contractor registration number for egress work?
Idaho requires contractor registration for most jobs over $2,000. Ask for the number; registered contractors must show it on their contracts.
Related services
More background: Idaho Falls basement finishing guide.
Need more room without moving?
Call and a local basement finishing contractor will walk the basement and the permit with you.