DAP Products Inc. The Home Depot The Home Depot - Eco Options

How To Seal An Interior Window CLICK TO PRINT

Once you have identified air leaks around your interior windows using our "how to find air leaks" guide, use these directions to seal them up. For sealing interior windows, you can use several products:

Latex caulk:

Easy to apply and clean up, latex caulk can be used to seal up small air leaks and gaps. If the gap is greater than ½" in width, use a foam backer rod first, then apply the caulk over the backer rod.

  • Be sure to read the entire package to ensure you have all materials the job will require and to budget for dry times in your project. Carefully review all safety precautions on the package.
  • Clean and dry the surface you will be sealing to ensure it is free of all dirt, dust, grease, old caulk and debris. (To remove old caulk, carefully use a utility knife or a caulk removal tool. Once completely removed, wipe away any debris. Use a rag to wipe the joint surface with rubbing alcohol or an over-the-counter disinfecting spray, rinse thoroughly with water, and dry.)
  • Apply the painters tape to mask off areas around the joint where the caulk should not appear and to help give a straight caulk line.
  • There are many different nozzle designs on caulk cartridges. Read the instructions of your select product for how to cut the nozzle. Some nozzles have a foil seal that will need to be broken.
  • Load the cartridge into the caulking gun. Applying steady pressure to the trigger, fill the joint around the window with an even bead of caulk. It is best to push the caulk ahead of the nozzle to ensure that it gets into the joint for a proper seal. Follow with a finishing tool to smooth the bead.
  • If you applied painters tape, remove the tape prior to the caulk skinning over. To correctly remove tape, lift the edge up at a 45° angle away from you, and carefully place in a trashcan.
  • Wipe away excess caulk with water and a damp cloth before the caulk dries. Excess dried caulk will need to be cut or scraped away.

Silicone caulk:

The application of silicone caulk is very similar to latex caulk. Two notable exceptions are that silicones must be cleaned up with solvent cleaners, not water. And, typical silicones are not paintable. Read label instructions carefully.


Rubber foam weatherseal can be purchased in a variety of thicknesses and lengths and is an easy-to-install solution if you can easily pull a piece of paper through the window when it is closed.

  • Be sure to read the entire package to ensure you have all materials the job will require, and make sure you have a clean and dry surface that is free of all dirt, dust, grease and debris.
  • Apply in strips across the top and bottom of the window itself and across the rail lock. For added insulation, weatherstrip can also be applied on the side of the window frame.