Window replacement costs in Philadelphia

Nearly two in three Philadelphia homes were built before 1960, the Census Bureau's survey shows. That's a lot of old houses, and a lot of old frames.

If you own a one- or two-family house, L&I keeps a straight swap simple. Replacing windows that aren't fire-rated needs no permit, as long as nothing structural changes and each opening keeps its location, shape and size.

Houses on the city's historic register are a different story. L&I's EZ permit route for windows doesn't apply to buildings the Historical Commission lists as historic, and the Commission reads window details closely. In a 2021 Girard Estate case, the owners of a 1909 house proposed aluminum-clad windows on the front and vinyl on the sides and rear. Staff wrote that vinyl wouldn't match the historic wood windows well enough, while aluminum-clad windows with the right details could. The recommendation asked for aluminum-clad on the sides and rear too, the original two-over-one panes on four narrow windows, and new glass set in the same plane as the old.

When a job does go through L&I's EZ permit, there's a number for the glass. Replacement units can't have a U-factor above 0.32, and the gap between each new frame and the old opening has to be sealed.