Insulating Window Weight Pockets

Remove exterior flat casing to reveal weight pocket.

Insulating window weight pockets.

These houses typically have no water management details around windows doors which works while the wall is open but will cause issues with insulation. Check the fit of the brick molding. Remove sash weights for upper sash the ones closest to exterior wall and replace pulleys with the pullman device that fits into the pulley hole. That will address any issues with the weight pockets.

If there is a gap i would caulk it. We use a router to grove the sides of the sash so that the sash can move along an interlocking metal track. For window weight pockets i just blow out as much dust as possible then spray the area with water then canned foam the cavity. Use foil tape to seal the joint between the window jamb and foam insulation.

Then cut strips of 2 foam board to fit into the wieght pocket where the weights used to be. Cut strips of foil faced rigid foam insulation to fit into the weight pockets. It may be be covered with lath and plaster as well which would open up another can of worms. Use a hammer and pry bar to carefully remove the wood trim from around the inside of the window exposing the sash weight pockets.

I would not try to fill in the weight pockets with any insulation. I did this on several windows. Insulating window weight pockets i am not 100 sure that just removing the casing will reveal the cavity. Stack strips to completely fill the void.