How to expand wall opening for through the wall AC?

Old 08-06-18, 09:13 AM
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How to expand wall opening for through the wall AC?

I'm helping my GF with an AC/carpentry project and looking for some advice. My GF has a "through the wall" AC unit that is 10+ yrs old and no longer works. We pulled it out and she bought a new unit that is suitable for "through the wall" installation (most window units are not). Because there is very little standardization in the world of AC units, the existing opening (and sleeve) is about 1" too narrow.

It was framed out when it was installed 10 yrs ago and those 2x4's are not load bearing. So I need to remove about 1" from one side, or 1/2" from each side. I would prefer not to take the entire wall apart and redo the framing for the AC unit. What is the best method to do this? I was thinking about using the circular saw and make cuts in the 2x4 and then use a chisel to remove them the wood between the cuts.

Am I on the right track or is there a better way to go about this? Appreciate any advice!

- marc
Old 08-06-18, 09:23 AM
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You will not be able to cut all the way through and not sure if you can get to both sides but your going to need something else, like a saws all to get into the corners. Beating with a chisel is not going to work.
Old 08-06-18, 10:24 AM
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Look at how the framing was done originally. If the AC was added as a retrofit they had to get the framing in somehow. Either they opened up the wall or they did the work through the opening, possibly by screwing the framing into place. Hopefully you can just unscrew and remove the blocking/framing they installed 10 years ago.

One option is to use a Sawzall to cut the extra space you need. A circular saw isn't recommended since you may hit nails. Make sure you take any pictures off the walls as the vibrations can knock things off the wall. The next big question then is how are you going to finish off the exterior to make it weatherproof and look good?

Or, just open up the wall on the inside. Sheetrock is easy to replace or repair. With that out of the way it's a lot easier to move or add framing as needed.
Old 08-06-18, 11:40 AM
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Hard to say when we can't see it. If the side 2x4s were added last you might just be able to remove them. Otherwise sawzall the 2x4s on the side out (one cut at the top and bottom) and see what you find.

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