Home>Discussions>INTERIORS>Molding & Carpentry>Insulating interior window frames/sills?
3 posts / 0 new
Last post
Insulating interior window frames/sills?


I live in a 100 year old building that was gut renovated about 4 years ago. It seems that the contractors were very stingy with the insulation, particularly around the window frames. We installed new, high quality windows last fall, and the air continues to leak in, which leads me to believe that a lack of insulation around the window frames and sills is the actual problem.

My question is, can insulation be safely blown behind the drywall? Is this something that a do it youself-er could handle, or would I need a pro for something like this? What type of insulation could I use?

Thanks in advance!

Timothy Miller
Re: Insulating interior window frames/sills?

Hi i'm restoring my 107year old home an have removed and replaced some windows. Did the contractor remove the old window jambs or just put in new inserts in your home? I ask as the old windows likly have a chase for weights to move up and down in to aid in opening the windows. This void on both sides of the window opening is likly the air infiltration source.
Without seeing the windows i would suggest removing a piece of the vertical interior window trim to see if this void exists and if no insulation in it then i would spray foam insulation into each cavity. Or pack in fiberglass insulation or have cellulose blown into the voids on each window. The spray cans of foam are a little pricey but they fill the voids well with a closed cell foam so no air movement and great insulation factor. If you use the foam be sure to wear water proof gloves as the foam stains hands badly.

Re: Insulating interior window frames/sills?

Thanks for the reply, sounds reasonable, and not too hard to do!

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.