How to Caulk and Seal Around Windows and Doors

Gaps around windows let heated and cooled air escape and increase your energy bills.

  • Fill small cracks and gaps with caulking.
  • Fill larger cracks with foam backer rod of the appropriate size by pushing it into the gap with a putty knife, then apply caulking on top of it.
  • Still larger gaps and holes can be filled using aerosol cans of expandable foam. After the foam has cured, trim it flush, and stain or paint it to match the house.


  1. Hello, We have a bay/bow window on the front of our brick house which was built in 1977. The window juts out a bit from the brick. I noticed that some insulation (foam strip) was dangling from beneath the outside of the window. I got down on my hands and knees and looked under and noted that there was a gap between the bottom of the window and the brick. We get carpenter bees here in NC and I am afraid they may get inside the house (fyi we are on a slab, no crawl space). I am not sure whether the gap is supposed to be there. Please let me know if it should be filled in and what product should be used.
    Thank you.
    Elizabeth Morgan


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