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Last Updated: , Created: Friday, December 7th, 2001

How can I make a basement window larger?

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Tony in Burlington has extremely small (8" x 31") basement windows (that sounds more like a gun turret than a window) and he wants to make them bigger. If he cuts into the concrete and makes them bigger will he need reinforcement for new vinyl windows?

If existing windows are showing no signs of trouble like jamming, they are probably supported properly above them. That means simply that the weight of the house above the windows is carried somehow over to the two sides of the window and not down on the middle. The first photo shows a very old house with the boards above the window just barely showing some stress. If you were to cut the foundation out to the right of this window without more support above, that floor joist would probably come crashing down. That is the key, you can cut an opening as far as you want directly down as long as you do not widen what is presently there. As soon as you cut wider, you need a registered contractor or structural engineer to tell you what you need to do to support the weight over this new opening.

Surprising changes can be made to a basement by cutting so far down that you can install standard sized windows, not small horizontal "basement" windows. Of course to do this you need special "window wells" that hold the soil quite a ways back. In fact once you have done this, you can landscape inside the window well and even build an emergency escape ladder out of the basement window well. Don't try this in areas that have flooding problems or poor landscaping that will direct runoff to the window well. Also, in clay soil you will need to fill in around this underground structure with well drained gravel to prevent frost heaving. Where you can handle water flow and frost problems, this brings natural light and openness to a basement that you probably never thought possible.

Keywords: Windows, Structure, Basement, Window Wells

Article 1576