Every sleeping room in Idaho needs at least one emergency escape opening, and Idaho jurisdictions enforce the International Residential Code's numbers: a clear opening of at least 5.7 square feet (5.0 square feet for grade-floor openings), at least 20 inches wide, at least 24 inches tall, with the sill no more than 44 inches above the floor. The window must open from inside without keys, tools, or special knowledge.
What "Clear Opening" Actually Means
Clear opening is the hole you can physically climb through when the window is fully open — not the frame size on the order sheet. This trips people up constantly. A window that measures 20 by 24 at its minimums gives you only 3.3 square feet, well short of 5.7; you need one dimension to be generous. A 3050 double-hung sounds big, but only half of it opens. A casement, by contrast, swings its entire sash clear, which is why a casement around 2'8" × 4'0" passes while a much larger slider can fail. Always check the manufacturer's published clear-opening spec for the exact unit.
Basement Bedrooms Are Where This Bites
Finishing a basement bedroom in Boise or Meridian is the most common place we see egress problems. Legally calling that room a bedroom requires a compliant egress window, and if the sill sits below grade, a code-compliant window well too: at least 9 square feet of well area, 36 inches of projection, and a fixed ladder once the well is deeper than 44 inches. Inspectors check these numbers, and appraisers won't count a non-conforming bedroom.
Sizes That Typically Qualify
- Casements: roughly 2'8" × 4'0" and larger
- Double-hungs: roughly 3'4" × 5'0" and larger
- Sliders: roughly 4'0" × 4'0" and larger — verify the spec
Wood Windows Inc has been sizing egress windows across the Treasure Valley for 46 years, and our in-house installers — never subcontractors — handle the cutting, flashing, and wells. Call (208) 376-2200 for a free in-home measure and we'll confirm code compliance before you order.
Frequently Asked Questions
Do egress windows require a permit in Idaho?
Usually, yes. Cutting a new opening or enlarging an existing one for a basement bedroom is permitted work in Boise, Meridian, Nampa, and most Treasure Valley jurisdictions. A straight same-size window replacement typically isn't, but confirm with your city's building department.
What are the window well requirements for a basement egress window?
If the sill sits below grade, the IRC requires a window well with at least 9 square feet of floor area and a minimum 36-inch projection from the foundation. Wells deeper than 44 inches also need a permanently attached ladder or steps.
Can a horizontal sliding window meet egress?
It can, but only half the window opens, so the unit has to be large — generally around 4 feet wide by 4 feet tall or bigger to clear 5.7 square feet. Casements meet egress in a much smaller frame because the entire sash swings out of the way.
Sources & Testing Data
Last reviewed 2026-07-05 by Wood Windows Inc — (208) 376-2200