Basement window well (margelle): what it is, how serious, what it costs

A window well, « margelle » in a French report, is the enclosure, often corrugated galvanized steel or plastic, around a basement window that sits below ground level. It keeps the soil away from the window and lets light in.

To do its job, its bottom must sit lower than the bottom of the window and drain (gravel, a drain tied to the foundation drain), and its rim must stand a little above the ground so surface water does not run into it.

The risk is water. A window well that is too shallow, full of leaves or without a drain fills up during snowmelt or a heavy rain, and the water comes in through the basement window.

In analyses, it usually lands under “Can wait”: it is maintenance or a targeted fix. It moves up when the report notes water marks below the window, or when it is a basement bedroom window: that window must let someone get out in a fire, and the window well must leave enough room to do it.

Cleaning the window well and getting its drain working again: $150 to $400. Adding drainage to a window well that has none: $400 to $900. Installing or replacing a window well with its drainage: $800 to $1,800 per window.

These are ballpark figures for Quebec, to be confirmed with quotes.

1. Does the window well have a drain at the bottom, and is it clear?
2. Is the bottom lower than the window, and does the rim stand above the ground?
3. Did you see water marks below this window, inside?

Does your report mention a window well? Upload it: in five minutes, I tell you what comes first, what to have checked and what to ask the seller.

As soon as a basement window sits below the ground, one is needed to hold back the soil. A clear cover helps keep it dry; over a bedroom window, it must open easily from inside.

A drainage or excavation contractor for the drain and the installation. Cleaning it, you can often do yourself every fall.