Egress & Basement Window Replacement in Pennsylvania
Written by the LehighValleyWindows.com editorial team ·
Basement windows are the most neglected openings in the house — original steel or aluminum hoppers from the 1950s, fogged glass block, or rotted wood units letting moisture into the one part of the home that’s already fighting dampness. And if you’re finishing a basement or adding a bedroom down there, the conversation changes from replacement to egress: a window big enough to climb out of in an emergency. Here’s how both projects work in Pennsylvania, and what the code actually requires.
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When code requires an egress window
Pennsylvania municipalities enforce the Uniform Construction Code, which follows the International Residential Code on emergency escape openings: every sleeping room needs one, and so does a newly finished basement in most cases. The commonly enforced numbers are a clear opening of at least 5.7 square feet, a minimum opening height of 24 inches, a minimum width of 20 inches, and a sill no more than 44 inches above the floor.
The key word is clear opening — the space you could actually climb through with the window fully open, not the glass size on the order form. A double-hung that measures big on paper often fails the clear-opening test because only half of it opens. Casement-style egress units pass most easily. Confirm specifics with your municipality; townships interpret finished-basement rules differently.
Replacing like-for-like basement windows
If you’re simply replacing tired basement windows in an unfinished basement or a laundry area, no egress upgrade is triggered — a straightforward swap into the existing opening is normal. Hoppers (hinged at the bottom, opening inward) and small sliders are the standard styles, and both come in modern insulated, low-maintenance frames.
This is also the cheapest meaningful comfort upgrade in many older homes: original single-pane steel basement windows are effectively holes in the foundation, and they rust, sweat, and feed cold air to the floor above. New sealed units warm up the first floor more than most people expect.
Cutting a larger opening: the real egress project
Turning a small basement window into a code-compliant egress opening means cutting the foundation wall, installing a header if needed, setting a larger window, and excavating a window well outside — typically with a well at least nine square feet in area and a permanent ladder if it’s deep. This is concrete-cutting, drainage, and waterproofing work, not just a window swap, and it prices accordingly.
Done right, it’s transformative: legal bedroom space, real daylight, and a safer basement. Done wrong, it’s a water-intrusion problem you’ll chase for years. Drainage at the bottom of the well — tied to the footer drain or a sump path — is the detail that separates good installs from future leaks.
Materials below grade: moisture wins arguments
Basement openings live in the dampest microclimate the house has. Bare wood frames struggle there; vinyl, fiberglass, and composite all shrug it off. Glass block has its place for fixed, secure openings, but it provides no egress and little ventilation.
Whatever the frame, insist on proper sealing between the frame and the masonry — that joint, not the glass, is where basement windows usually leak air and water.
Permits, and how to get a real number
Like-for-like replacement usually doesn’t require a permit, but cutting a new or larger opening in a foundation wall does, and a finished-basement project should be permitted as a whole. A contractor who waves this off is volunteering you for problems at resale.
Use our free matching form and we’ll connect you with a vetted local expert who can assess your basement openings in person — what can be swapped, what egress would take, and what each path costs, in writing.
FAQ
Does an unfinished basement need an egress window?
Generally no — the requirement applies to sleeping rooms and, in most municipalities, to newly finished habitable basement space. Replacing old basement windows like-for-like in an unfinished basement doesn’t trigger an egress upgrade.
What size does an egress window have to be?
The commonly enforced IRC numbers are 5.7 square feet of clear opening, at least 24 inches tall and 20 inches wide, with the sill no more than 44 inches off the floor. Note that both minimums can’t be true at once — hitting 5.7 square feet requires exceeding at least one of them. Your municipality has the final say.
How much does an egress window cost?
A like-for-like basement window swap is one of the cheaper openings in the house. A full egress conversion — concrete cutting, the window, the well, and drainage — is a different project entirely and typically costs several times more. Get both scoped in a written quote before deciding.
Will a window well leak?
Not if it drains. The well needs a gravel base tied into the footer drain or another drainage path, and a cover keeps rain and leaves out. Wells leak when they’re installed as a hole with no exit for water.
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