how to extreme

Installing a Window AC in the Wall

Air Conditioner, Construction How-To, HVAC August 2, 2016 Sonia










By Larry Walton, photos by Mark Walton

We don’t get much heat or humidity where we live but when we do, temperatures can get over 100 degrees, which makes having air conditioning a pretty good idea. Getting through those few weeks of hot weather can often be accomplished with a window air conditioner or two.

Being from a region where AC is not often needed, I’ve used lots of window air conditioners, but not often in the way they were designed. This is primarily because these units can interfere with emergency egress. Building codes rightly require that bedrooms provide an alternative escape route in case the door into the room cannot be used, and this alternative escape is often through the window. Expecting children and others with physical limitations to handle an air conditioner before they can get out of the room can be disastrous.

Some of our relatives use freestanding portable air conditioners, but these also have their drawbacks. They take up room and still need to be exhausted out-side, causing window access challenges as well.

Installing a window air conditioner in its own glass-less window opening is a good way to handle several issues raised by window units while taking advantage of their low costs and compact size.

I usually install these units high on the wall so other furniture can be used below, and so the exterior portion can be better protected by the overhang of the eaves. This is important because I leave the units in place year round. We find a few more occasions to use them throughout the year for unseasonal hot days and even to provide a little white noise when ambient noise in the house or in the neighborhood gets a little out of spec.

Here’s how I made a window opening in a bedroom to be used exclusively for an air conditioner.

Step by Step


Use a stud finder to locate two adjacent stud bays that will provide enough room for the opening.


Build a jamb box of 1×6 pre-primed pine about 4 inches wider and 4 inches taller than the air conditioner required. This allows for a replacement unit, which might be larger. It also provides plenty of air circulation around the appliance, which can get a bit tucked in depending on the thickness of the wall.


Use a Speed Square and a torpedo level to make sure the jamb box is both level and square while marking the out-side perimeter of the box on the wall.


Use a multi-tool to cut the drywall just outside of the pencil line. I wanted a tight fit to avoid using trim on the inside, but you can plan to use trim if you want. Note the shop vac hose in my left hand to grab most of the drywall dust.