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Rick, General Contractor
Category: Home Improvement
Satisfied Customers: 21391
Experience:  Licensed construction supervisor with 35+ yrs. experience.
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I'd like to know what would be the best way to "seal" the

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I'd like to know what would be the best way to "seal" the hole in the wall around the AC unit. Is there any kind of product/material that I could buy and simply put it around the AC?

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. First I’ll need some more info so I have a more complete picture of you situation.

Can you explain a bit more about this issue? Do you have a through the wall AC unit that has a gap between the unit case and the opening in the wall? if so how big is the gap?

Customer: replied 10 months ago.

Hello Rick,

thanks for your answer.

Yes, it is a unit through the wall.

The hole is 27 x 17 inches and the AC unit is 24.2 x 14.5 inches. So yes, I'd like to fill/close/seal this 2.8 x 2.5 inches gap.

Ok, that's a really big gap to fill. There is no product made specifically to fill a gap that big so we'll have to improvise. I'd use rigid foam insulation here's an example from Lowes

Cut pieces to fit tight into the openings. You can cut it with a knife but a saw is easier. You can paint it with exterior latex paint to protect if from UV sunlight on the outside and for a better color inside if you don't like the bluish green. Paint the outside before you install it if it's difficult to get to from outdoors.

Customer: replied 10 months ago.

Hello Ricky,

thank you so much for your answer. Although there's still one thing left... Is there anything I can do after filling the gap to give it a better finishing?


Inside you could cover it with 1/4 birch veneer plywood or something similar. Outside painting it is your best option. You could also paint the inside like I said before

Do you have any more questions?

Rick and other Home Improvement Specialists are ready to help you