Help installing a window AC thru the wall

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Blog entry by John Gray posted 06-14-2008 04:33 PM 33073 reads 0 times favorited 10 comments Add to Favorites Watch

I have a window AC unit and I want to install it in/thru the wall of my shop, conventional 2×4 wood stick framing. Does anyone have ideas/links to share about an installation of this type – framing, trimming inside and outside (outside is vinyl siding), and any other info? Thanks in advance!

-- Only the Shadow knows....................

10 comments so far

View joey's profile


396 posts in 3928 days

#1 posted 06-14-2008 06:10 PM

its just like installing any window, you need to make sure you install a load bearing header first, leave enought room to freely slide the unit in, and out then trim it from the out side. I usally layout the hole on the inside of the room, then I cut the drywall, then cut out the studs and unstall a header and jacks. you might need to go a little larger to go from stud to stud, but thats all right on the inside just don’t cut the hole on the out side that big. Now that you have a header installed, frame in your opening to the size of your unit, then use a long drill bit to drill hole to the outside corners. the I go outside and cut the siding, I normally do this with a circular saw with a plywood blade and I install the blade backward, it will cut the vinyl siding by fiction and not grab it just go slow, or you can use a razor knife or some sheet metal cutters what ever you are comfortable with, after you have the siding cut thru you need to cut the sheathing with a saws all. You can use J mold to trim the siding. I would give myself enough room to try to use some type of seal for the AC to set on. on the in side just patch the drywall trim out the opening with some trim and your in in business. keep in mind window units only last so long and your next one more that likely will be a different size so having a bigger header installed saves the trouble of redoing that job in a few years when you put a bigger unit in or hopefully they will get smaller. hope some this helps.

-- Joey~~Sabina, Ohio

View GMman's profile


3902 posts in 3721 days

#2 posted 06-14-2008 06:17 PM

you do as joey mentioned I pretty sure you cannot go wrong

View motthunter's profile


2141 posts in 3823 days

#3 posted 06-14-2008 06:50 PM

make sure that you install it as far from where you make dust as possible. You also may want to consider doing something extra to pre-filter the air so that you don’t have to change the air conditioner filter every other minute.

-- making sawdust....

View Duckarrowtypes's profile


68 posts in 3928 days

#4 posted 06-14-2008 10:36 PM

I built a little support for mine out of 2×4 and then I attacked the wall with my reciprocating saw. Sealed with Great Stuff from a can. G H E T T O but very functional.

View Taigert's profile


593 posts in 3864 days

#5 posted 06-15-2008 07:48 AM

Make sure to slope the unit a liitle towards the outside so the condenste will drain outdoors.

-- Taigert - Milan, IN

View John Gray's profile

John Gray

2370 posts in 3909 days

#6 posted 07-09-2008 06:56 PM

Thanks everbody.

-- Only the Shadow knows....................

View John Gray's profile

John Gray

2370 posts in 3909 days

#7 posted 07-24-2008 01:12 AM

It’s installed and cooling my shop HARRAH!!!!!!!!

-- Only the Shadow knows....................

View Tomas21's profile


4 posts in 2392 days

#8 posted 07-11-2012 07:36 PM

Hi John,

Any tips / pointers you can share about your through the wall install?

Did you install jacks, sill plate, etc?


View John Gray's profile

John Gray

2370 posts in 3909 days

#9 posted 07-11-2012 08:17 PM

Used a header, jack studs, and a sill plate just like installing a new window in an existing wall.

-- Only the Shadow knows....................

View Wolfmont's profile


20 posts in 2333 days

#10 posted 09-03-2012 06:13 PM

Have a question about this that really is outside the scope of this site, but does connect to John’s original question. We are building a new home. We built an attached shop on one end of the house, 20×25, and the outside wall is 8” cinderblock, with all cells poured and rebar in place. We don’t want the shop to be part of the main HVAC system because of dust, paint fumes, solvents, etc. But in Georgia, you really need to have AC because of both the summer heat and the humidity.

So, we considered a mini-split but those are outside our budget range for the shop. Next, we talked to a couple of contractors about a PTAC unit (the same sort of unit they put through walls in motels), that provides both heating and cooling… not that we would need the heat very often. That would be about $1,500 installed.

Just this last week I got a flyer in the mail for Sears window units on sale, that do both heating and cooling. As I say, the heating would be minimal. A 12,000 BTU unit would cost me less than half the cost of the PTAC unit, even including renting a bulldog saw to cut through the wall, or paying someone to do it for me.

That being said, is such a thing compliant with the NEC or other IRC rules? If not, can you give me chapter and verse on that? For that matter, if it explicitly IS allowed, it would be great to have chapter and verse on that as well.


-- -- Tony

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