Why bedrooms have their own window rule
The International Residential Code sets minimum sizes for the windows in sleeping rooms so a person can climb out in an emergency and a firefighter in full gear can climb in. Section R310 is where those numbers live, and it applies to every new or replaced sleeping-room window, in a basement or above grade.[1]
The numbers a bedroom window has to hit
The code sets a minimum net clear opening of 5.7 square feet, with an exception down to 5 square feet for a grade-floor opening.[1]
Within that area, the opening also needs a minimum clear height of 24 inches and a minimum clear width of 20 inches; a window that clears the square-footage minimum on paper can still fail if it's too narrow or too short in either dimension.[1]
The sill also can't sit more than 44 inches above the finished floor, so a taller sill height fails even if the sash above it is generously sized.[2]
"Net clear opening" means the space you can actually climb through once the window is open, not the overall frame size or the glass size on the spec sheet. That distinction is where a lot of otherwise-fine-looking replacements go wrong.
How a routine replacement can quietly fail egress
Swapping a single-hung window for a fixed picture window, or moving from a full-sash-opening style to one with a smaller operable vent, can shrink the net clear opening even when the overall frame size in the wall stays the same.
Grille patterns, add-on hardware, and interior screens that intrude into the opening can also eat into clear width and height enough to matter on a borderline-sized window.
Below-grade bedrooms need a window well, too
A basement sleeping room can still meet R310 on paper while sitting behind an undersized window well, since the well itself carries its own minimums: at least 9 square feet of horizontal area, with a horizontal projection and width of at least 36 inches.[3]
A well deeper than 44 inches also needs a permanently fixed ladder or steps, because the code assumes whoever is climbing out is doing it in a hurry, not stepping carefully.[3]
If a basement window job doesn't touch the well in front of it, ask your contractor to confirm the existing well already meets these numbers. A new window can't fix an undersized well.
Permits and paperwork
Rules on when a window job needs a permit vary by city and county, so ask your contractor directly rather than assume. Florida's version of this rule is tied to money rather than the work itself: collect above a 10 percent deposit on a residential job, and state law now puts a 30-day clock on the contractor to file for permits, plus 90 more days to begin once those permits clear.[4]
That kind of rule exists precisely because permit and inspection steps are easy to let slide once money has changed hands. Get the permit responsibility and the completion date written into your contract, not agreed to verbally.
What to check before you sign off on a bedroom window job
Ask your contractor to state the net clear opening in writing for the specific window and screen combination they're installing, not just the rough opening size. If they're replacing a bedroom window with anything other than a like-for-like size and style, ask them to confirm in writing that the new opening still meets R310.