Enlarging an existing basement window
Already have a small window where you want the escape opening? Cutting it down is often the simplest path.
An existing basement window gives an installer a head start: the top of the opening is already there, and the wall above it is already carrying load around it. Enlarging usually means cutting the opening deeper toward the floor and sometimes wider, then putting in a taller window and a bigger well.
When does enlarging make sense?
- The old window is in a room you want to use as a bedroom
- The old window opens less than 5.7 square feet, or the sill sits more than 44 inches above the floor
- The old well is too small to let someone climb out
- The wall outside is reachable without moving a deck, a patio or a driveway
Measure before you assume
A window that looks large may still fail. The test is the net clear opening with the sash fully open: at least 24 inches high, at least 20 inches wide, and 5.7 square feet total. A 24-inch-high opening has to be about 34 inches wide to reach 5.7 square feet, so many older basement windows miss on one dimension or the other. Measure the actual opening, not the frame.
What gets added?
- The lower part of the wall is cut away to bring the sill down
- A taller window, often a casement, goes in the new opening
- The old shallow well is removed and a larger, deeper one is installed
- A ladder goes in if the new well is more than 44 inches deep
Common surprises
Older Bismarck homes near downtown and in the Cathedral District can have foundations that were patched or modified over the decades. Rotted wood bucks around old windows, wiring routed under the sill, and water lines along the wall all come up. A good installer will look from inside and out before quoting.
The installer prices the job after seeing the wall, the yard and what's on the other side of the foundation. We don't quote prices, and any figure given over the phone is only a rough starting point until someone has measured.
Where we connect you with help
Common questions
Can I just replace my basement window with a bigger one?
Only if the existing opening already meets the egress size. In most basements, the wall has to be cut lower to fit a window that opens wide enough.
Is enlarging cheaper than cutting a new opening?
Sometimes, because part of the opening already exists. It depends on the wall, the depth and what's in the way outside. Get both options quoted if you have a choice of walls.
Related services
- Basement egress window installation
- Window wells, ladders and drainage
- Window well covers
- Bedroom egress code compliance
More background: Bismarck egress window guide.
Finishing the basement or adding a bedroom down there?
Call now and a local egress installer will look at the wall, the yard and the code requirements, then quote the job.