How to Insulate Gaps around a Window AC, by Hammer n Curls on YouTube. 5 min 36 s.
- Video length
- 5 min 36 s
- Time to do it
- 20 minutes
- Difficulty
- Easy
- Steps
- 8
What you need
Steps
Unplug the air conditioner and let the area dry. Check the gap on both sides and along the top and bottom of the unit.
Measure each gap with a tape measure. Note the width and depth so you can choose foam, tape or caulk for that spot.
Clean the window frame, sash and AC casing with a damp cloth. Let the surface dry completely before adding any sealant.
Cut foam insulation strip or backer rod to the length of the gap. Use scissors or a utility knife and make clean cuts.
Press the foam into the gap with your fingers. Fill it until the foam sits just below the surface, not bulging out.
Peel the backing from weather sealing tape. Press it firmly along the seam between the AC and the window frame.
Load the caulk tube into the caulking gun and cut the nozzle at a small angle. Run a thin bead along narrow gaps and smooth it with your finger.
Check the seal from inside and outside if you can reach safely. Patch any open spots, then let the caulk cure as the tube label says.
Tips and common mistakes
Work on a dry day so the tape and caulk can stick to a clean, dry surface.
Do not cover the AC drain holes, vents or weep holes; trapped water can rust the unit or damage the window.
Use foam for wide gaps and caulk for narrow cracks; tape works best on straight, smooth seams.
If you must reach outside, use a stable step stool or ladder and do not lean out of the window.
Questions
Do I have to take the air conditioner out of the window?
No. You can seal most gaps with the unit in place. Remove it only if the gap is too deep or damaged to reach safely.
What should I use for a very wide gap?
Use foam backer rod or foam strip to fill the depth first, then cover the surface with weather sealing tape or caulk.
Can I use expanding spray foam around a window AC?
It is better to avoid it. Expanding foam can bow the window frame and is hard to trim cleanly around a unit.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
