I purchased my home a couple of years ago and this year I am going to replace the deck and build a fence. The deck was in terrible condition so I completely took it down. To my surprise I found 2 below grade windows under my deck that had been dry walled over on the inside. In fact the previous owner even left the glass panes in the windows. I want to fix this permanently and fill it in so it won't ever be a problem again. What is the best way to do this?

  • If it's a bedroom, they are (should be) egress windows and must be operable.
    – Mazura
    Sep 20 '14 at 19:41

Jeff, you didn't say what material the windows were in. poured concrete foundation wall, framed wall?? Is there siding around the windows? A concrete wall could be filled with bricks and mortar. If it is a framed wall, build a framed box, shiething, then some flashing, lots of silicon caulk and match the siding. A picture would be a great help on this one.


In a similar situation, I cut a piece of flashing to the size of the window opening, then used metal screws to attach it to the (also metal) window frame. I then sealed around the opening and the screw heads using Lexel caulk.

I thought about filling in the opening with concrete afterwards but never bothered.


If you want something relatively quick and easy, you could fill it up with a 2-part Polyurethane Foam (info). It's really easy to apply, is airtight as long as you apply it properly and you're going to be covering it up anyway, right? A few months ago I had a home energy audit done on my house and the technician recommended this stuff to improve temperature retention and seal the house up. I've re-insulated a fair amount of my house with this stuff and it's great.

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