How to Seal Drafty Windows and Lower Your Heating Bill

Time required: 30-45 mins per window · Difficulty 1/5

Est. DIY Parts: $8 - $18 · Pro Service: $80 - $150 · Est. Savings: $65 - $140

* Estimates based on regional/national contractor rate benchmarks. Actual part prices vary by brand and retailer.

Parts & Tools You'll Need

Clean the window frame and sash Wash the sash tracks and frame with soap and water, then let them dry completely — weatherstripping won't stick to dirty or damp surfaces.
Measure and cut the V-strip Measure the height of each side of the window sash and cut the V-strip to length for the upper and lower sashes.
Apply the V-strip to the sash channels Peel the adhesive backing and press the V-strip into the vertical channels where the sash slides, with the open 'V' facing outward to create tension against the frame.
Test that the window still opens smoothly Open and close the window a few times to make sure the new strip isn't binding — trim or reposition it if the sash sticks.
Caulk the fixed frame-to-wall gap only Apply a bead of clear removable caulk only where the outer window frame meets the wall or trim — never caulk the operable sash itself, or you won't be able to open the window.
Smooth and let cure Smooth the caulk bead with a wet finger and let it cure per the label before washing the window.