Basement windows get replaced last or never. They are low, small and often behind a shrub, and the old wood frame around them is quietly letting in cold air and water. Here is what to know before you replace them.

What is a basement window?

A basement window is a small window set in the foundation wall, at or just above grade. Because it sits in concrete, block or stone instead of a wood framed wall, it is installed differently from the windows upstairs.

Basement window types

  • Hopper: hinged at the bottom and tilts in from the top. It vents well and sheds rain away from the opening.
  • Slider: one sash slides sideways. Simple and easy to open from a ladder or a step.
  • Fixed: does not open. Used where only light is needed.

If the basement is or will be a living space, see egress windows. A standard basement window is usually too small to count as an escape opening.

Basement window benefits

Less cold air and moisture

Old basement windows sit in rotted wood frames and single glass. A new vinyl window sealed into the foundation stops both the draft and the water.

Easy cleaning and venting

Vinyl hoppers and sliders open from inside without tools, so the basement can actually be aired out.

Low cost per opening

A basement window is the smallest and cheapest window in the house to replace, and often the one leaking the most for its size.

How to choose a basement window

Start with the wall. In poured concrete the window can be set square in the opening. In a fieldstone foundation the window cannot be fastened to round stone, so a wood frame is built into the opening first and the window is set into that. Ask how the head joint, where the foundation meets the siding above, will be sealed. That joint decides whether the window still looks right in five years.

See our basement window projects in Lawrence and Medford.

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