Des Moines Egress Windows Does Your Des Moines Basement Bedroom Actually Meet Egress Code? (IRC R310 Checklist)
August 14, 2026
Across this metro, a common problem isn’t a house with no basement bedroom - it’s a house with a basement “bedroom” that isn’t one. There’s a bed, a closet, drywall, carpet, maybe an egress-ish window. And then a home inspector, an appraiser, or a city rental inspection applies IRC Section R310, and the room quietly stops being a bedroom.
You can run the same check yourself in twenty minutes with a tape measure. Here’s the complete checklist, with the exact numbers every metro city enforces - Des Moines and Johnston through the 2024 IRC, West Des Moines through the 2021, Urbandale through the 2018, Ankeny through its own locally amended residential code. The editions differ; the R310 escape-opening numbers below do not.
First, the rule in one sentence
Every sleeping room needs its own emergency escape and rescue opening - a window (or door) big enough, low enough, and operable enough that a person can climb out and a firefighter in gear can climb in. One compliant window down the hall doesn’t cover the bedroom next to it. Room by room, opening by opening.
The checklist
1. Net clear opening: at least 5.7 square feet
Open the window as far as it goes and measure the actual unobstructed hole - height times width of the open gap, in inches, divided by 144. That’s net clear opening, and it must be at least 5.7 square feet (5.0 sq ft only for grade-floor openings, where the sill sits at or near ground level).
This is where most rooms fail, because the hole is always smaller than the window. A slider gives you roughly half its frame width when open; a double-hung gives you half its height. A window that looks generous can easily net out at 4 square feet. And note the trap in the minimums: 24 inches by 20 inches - the code’s floor for height and width - is only 3.3 square feet. You cannot hit 5.7 at both minimums; at least one dimension has to be meaningfully bigger.
2. Minimum clear height: 24 inches. Minimum clear width: 20 inches.
Measured on the same open, unobstructed hole. Hardware, stops, and sash that intrude into the opening count against you.
3. Sill height: no more than 44 inches above the floor
Measure from the finished floor to the bottom of the clear opening. More than 44 inches and the room fails - the code assumes a child or a smoke-disoriented adult has to get up and out without a ladder inside the room. This is the killer for the metro’s older stock: the original hoppers in a 1920s Beaverdale brick or a 1950s south-side ranch sit up at the joists, often 60+ inches off the slab. No replacement unit in that hole fixes it; the opening itself has to drop, which is saw-and-header work.
4. Operable from inside without keys, tools, or special knowledge
Painted-shut sashes, security bars without release hardware, and aftermarket locks that need a key from inside all fail - the opening only counts if it opens.
5. If the window is below grade: the well
- At least 9 square feet of horizontal area, with minimum 36 inches of width and 36 inches of projection from the wall. The old 12-inch-deep corrugated half-moons hugging mid-century foundations aren’t close.
- Deeper than 44 inches? Permanently attached ladder or steps - rungs at least 12 inches wide, projecting at least 3 inches from the wall, spaced no more than 18 inches on center. Most full-depth metro basements put wells past 44 inches, so no ladder is an automatic flag.
- The well can’t stop the window from opening fully.
6. If there’s a cover: removable from inside without tools
A screwed-down cover over an egress well converts a legal bedroom back into a violation. Covers must release from inside with no keys, tools, or special knowledge. (You still want a cover here - leaves and snow fill open wells - just a compliant one; see covers and drainage.)
7. The room itself
Egress is the big one, but inspectors also expect a sleeping room to meet the basics: minimum floor area and ceiling height, heat, and smoke alarms per the adopted code. If your finish predates permits - common in basements finished in the 70s–90s - those items ride along with the egress fix.
8. While you’re down there: the water check
Not a code item, but run it anyway: look for rust stains at the bottom of the well, silt on the well floor, and water marks on the buck frame or sill. A well whose gravel drainage bed has silted shut is slowly rotting the wood that holds the window to the concrete - hydrostatic pressure in this metro’s clay soil never takes a season off. Catching it now is a $300–$1,000 drainage rebuild; catching it after the buck fails is a bigger job.
Scoring your basement
Passed everything? Good - keep the paperwork from whoever built it, and make sure the well drainage still works before spring; a flooded well is how compliant openings rot into non-compliant ones. A well and drainage check is cheap.
Failed on the window or sill? The fix is enlargement - glass block or old unit out, sill dropped within 44 inches, new header and pressure-treated buck, compliant casement or slider, code well outside. That’s a full egress installation, typically $3,500–$6,500 in this metro, 1–2 days on site once your city issues the permit.
Failed only on the well, ladder, or cover? Cheaper: code-sized wells run $1,000–$3,000, covers $150–$600 - the pricing page itemizes all of it.
Failed because the room has no opening at all? Same full-install answer, with placement freedom: the new cut goes where the room’s layout and the joists want it.
Why this matters more in Des Moines than most places
Three local multipliers. Radon: Iowa is the most radon-prone state in the country - all 99 counties in EPA Zone 1, roughly 70 percent of tested homes above the action level - so basements here get mitigated and finished into living space at a rate most states don’t see, and every finished sleeping room triggers R310. Housing stock: the metro is deep in exactly the two basement types that fail - pre-war and mid-century rooms finished before anyone checked, and 2000s+ suburbs where one builder opening served an unfinished basement that has since grown bedrooms. The sale: appraisers count only conforming bedrooms, and a missing opening is the most common reason a basement room gets struck. The county assessor’s bedroom count won’t save the listing; the tape measure at the buyer’s inspection decides. Sellers who fix it before photos keep the count and the leverage - the code compliance upgrade exists for exactly that moment.
The honest close
If your room failed a line above, don’t panic and don’t call a window salesman - most failures are opening problems, not glass problems, and the fix is structural but routine: permit, saw, header, well, inspection. And if you’re not sure what you measured, the on-site measure here is free and settles it with a tape, not a pitch. One thing nobody honest will promise: the final pass, which belongs to your city’s inspector - in Des Moines proper, Ankeny, West Des Moines, Urbandale, or Johnston, each through its own building office. What you can control is building to the numbers above, exactly. That’s the whole trade.