Installing a wall mount a/c unit...

[Daytrepper]

I picked up a 25K btu wall a/c unit at Lowes over the weekend, on clearance.

Question is, what is the proper way to make an opening in the wall for this thing? Basically make a new "window" and install a header etc? A buddy told me a header wouldnt be necessary in a gable wall. Im not too familiar with framing, so not sure where to go from here. I want to tear up a minimal amount of drywall lol.

Which wall would be best? North, south, east wall? I'd prefer the west wall (gable wall), but it also gets the most sun, so that might hurt efficiency.

 

[Falcon67]

May depend on your stud spacing. If they are 24" OC and you don't have to cut a stud, it can mount on a 2x4 "sill" and single header attached to the existing studs. But a 25K will probably be wider than 22 1/2" and you may have 16" OC stud spacing. Then you would need to open the wall enough to install a proper header and bracing to make sure any roof loads get transferred down the studs. 25K should be a hefty unit, so you'll want a sturdy hole for it. Same as if you were cutting in a window, just different dimensions. I would not cut a stud in any wall and not use a proper header unless it was an interior non-load bearing wall.

AC units should work better with sun exposure.

 

[theoldwizard1]

A buddy told me a header wouldnt be necessary in a gable wall.

So what is going to support the studs/wall above the window and what is going to support the sill ?

Do it right. Cut the drywall out to the next stud left and right of the "window". Install jack studs and cripple studs below the sill. I would install some kind of trim board on the bottom of the header.

It really won't that much more drywall work.

Because your rough opening is going to be your finish opening, make sure you have an extra ½-1" of space between the sides and top of the A/C unit. You will need to fill this space with some kind of insulation.

You are likely going to use a 2x8 or 2x10 for a sill. Make sure to bevel it and but make a drip cut on the underside. Because the sill and jack studs are going to be exposed, make sure to prime and paint them.

I'd prefer the west wall (gable wall), but it also gets the most sun, so that might hurt efficiency.

It will.

Make certain the A/C unit is mounted with a slightly downward angle on the outside so condensation drains properly.

 

[Lambo nut]

A buddy told me a header wouldnt be necessary in a gable wall. Im not too familiar with framing, so not sure where to go from here.

If the building is built with trusses, including the gable ends, this would be true. No different then an interior non load bearring wall.

Kevin

 

[Daytrepper]

If the building is built with trusses, including the gable ends, this would be true. No different then an interior non load bearring wall.

Kevin

It is built with trusses.

It would seem to be alot less work to just frame an opening, without adding the header, jack and cripple studs. It is 16 OC all the way around.

 

[Lambo nut]

It is built with trusses.

It would seem to be alot less work to just frame an opening, without adding the header, jack and cripple studs. It is 16 OC all the way around.

As long as the gable end is also a truss, just frame the opening is exactly what I would do. The studs of the wall would not be bearing any weight at all.

Kevin