 |
Window Air Conditioner Through The Wall -
Trim Carpentry Details
|
In
This Article:
After the rough opening is made, the
siding is cut out and the opening is lined with jamb
material. Exterior trim is installed, and pieces of wood are
installed to secure the window air conditioner. A plug is
made to fill the opening during winter.
|
Related Articles:
|
| Skill Level:
3-4 (Intermediate to Advanced) |
Time Taken:
About 6 Hours |
By
Bruce W. Maki,
Editor
Start:
| Earlier,
while remodeling this second-floor office, I
framed in a rough opening for a window
air conditioner. Since the room had only one
window, I wanted the air conditioner to have its
own opening, rather than occupying the only
source of fresh air (and natural light) in the
room.
The black area in the picture is the back
side of the old Celotex fiber board that
was applied over the studs when this house was
built in the early 1960's. |
 |
|
 |
The first thing I did was cut away the Celotex
fiber-board. I used a Fein Multimaster to cut
through the fiberboard without cutting through
the siding. This could also be done with a
sharp utility knife. |
|
| After I cut
out the fiberboard sheathing, the back of the
Masonite siding was visible. I wanted to leave
the siding intact as long as possible, because
there were thunderstorms looming on the horizon. |
 |
|
 |
To determine the width of the jambs, I
measured from the outside of the fiberboard
sheathing to the inside edge of the drywall,
which in my case was 4-7/8 inches. Then I cut
my jamb materials to a width just slightly wider
than the thickness of the wall.
I used Azek® cellular PVC trim boards for
this job. I like cellular PVC because it's
stable, won't rot, and holds paint well. |
|
| I used a 1/2"
spade bit and drilled holes through the siding
at each corner of the wall opening. |
 |
|
 |
Then I stuck a reciprocating saw bit through the
corner hole and cut the siding, using the studs
as a cutting guide. |
|
| After the
siding was cut away, I had a nice view, but I
also had a liability, since the house was
now wide open to the elements. |
 |
|
 |
This is what the air conditioner cut-out looked
like from the outside. |
|
| I installed
the bottom jamb first, using 2-inch finish
nails. However... to prevent water from
puddling on the window sill, I installed some
shims beneath the bottom jamb. This gave the
bottom jamb about 2 degrees of slope. (I nailed
through the shims to keep them from moving
around.) |
 |
|
 |
Then I installed the other 3 jambs. I did the
top jamb first, followed by the side jambs.
Note that the lower ends of the side jambs were
cut to a 2-degree angle to fit the sloped bottom
board. I cut these jambs just a hair too long,
so they fit tightly against the top and bottom
after I tapped them in place with a hammer. |
|
| After the
jambs were in place there was still a lot of
work to do on the outside. At this point, I
laid the "window" casing against the opening and
marked the outside edges of the casing, so the
siding could be cut away a little more. |
 |
|
NOTE: Before laying out the
casing, I drew a line on the outer edge of the jambs, about
1/2" back from the inner edge. This gave me 1/2" of "reveal"
on the edges of the Azek jambs. Towards the end of this page
there is a picture that explains this concept.
 |
I cut away the wood siding with a circular saw (set
to cut just deep enough to penetrate the
siding). This is not an easy
job. The saw spits sawdust in your face, it's
difficult to cut across the overlapping part of
the siding, and it's tricky to keep your balance
while working on a ladder. |
|
Warning:
Use extreme caution when cutting
siding while working on a ladder. Cutting wood siding is
tricky enough... the blade can bind or pinch, throwing
you momentarily off-balance. When doing this work on a
ladder, you need to have a firm footing, a good grip on
the circular saw, and be ready for any kickback from the
saw. DO NOT reach far beyond the sides of the ladder...
take your time and move the ladder so you are working
without leaning sideways. |
|
What About Vinyl Siding?
Creating a hole in the wall with
vinyl siding should be fairly easy. When I work with
vinyl, I usually just remove a few panels of siding
around the area, install J-channel next to the trim that
surrounds the opening (whether it's a window, door, or
A/C opening) and then re-install the siding, cutting
notches in the panels where necessary. Under-sill
trim may be necessary below the opening, to
secure the top edge of the siding when it's notched for
the opening. |
|
Making The Exterior Trim From Azek®:
The side trim boards were just simple flat
boards cut to about 2˝ inches wide, with the bottoms cut to a 10
degree angle to mate with the angled sill.
The sill can be made two ways... either as
two pieces of Azek (nearly) horizontal that are glued together, or
two vertical pieces fastened to the wall. On this project I chose to
use the vertical double-board approach.
The top trim was made like
old-fashioned window trim with a "lookout" board that caps the
vertical piece:
| I cut a
couple of pieces of Azek with a 10-degree bevel.
These will form the top casing trim above the
opening. |
 |
|
 |
I applied PVC cement to the PVC trim... |
|
| ...and nailed
it together with 2-inch finish nails. This
piece will form the "lookout" trim above the
opening. The protruding top board should help
keep rain away from the opening. |
 |
|
Installing The Exterior Trim:
 |
I installed the top trim and then the angled
sill. |
|
| Then I cut
the side trim to the exact length and nailed
them in place with 2˝ inch finish nails. |
 |
|
 |
A Wide Reveal Is
Needed:
IMPORTANT: All 4 trim components were
installed about 1/2 inch back from the inside
edge of the jambs (i.e. 1/2 inch reveal).
This large reveal will provide a good surface
for the outer cover panel to seat against.
With ordinary window casing, the reveal would
normally be a matter of personal taste. I
usually make the reveal 3/16" when doing regular
trim, but this case is special. |
|
After the trim was nailed in place,
I caulked all the gaps with siliconized acrylic latex caulk.
 |
I installed this quick temporary cover to keep
the rain out. This was easy... I just cut a
piece of high-quality 1/2 inch plywood to fit
loosely between the trim boards (against
that 1/2" reveal) and then I cut a piece of
plastic with about 6 to 8 inches of overhang on
all sides. I stapled the plastic to the outside
of the cover panel, then I set the panel into
the opening and stapled the plastic to the edges
of the jambs on the inside. |
|
Note: I cut the cover panel
about 1/4 inch smaller than the width and height of the
inside dimensions of the exterior trim boards. This created
a 1/8 inch gap between the cover and the trim, or about 3/8
inch of overlap between the cover and the jambs.
Installing Blocks Of Wood To Support
The Window Air Conditioner:
Once the opening had been trimmed out with
jambs and exterior casing, I still needed to install some pieces of
wood to hold the window air conditioner in the opening.
| I fastened
this block of wood to the sill to support the
air conditioner. The A/C unit I used has a
shallow channel in the steel bottom pan, which
is about 3 inches wide. So I used a table saw to rip this 2x4 to
less than 3 inches wide, and I cut it as long as the
width of the air conditioner housing. The idea
is to have that channel in the housing sit right
on top of this board. |
 |
|
 |
Then I made
this "L"-shaped piece of wood, which spans the
full width of the opening.
This is just a 2x4 that I ripped narrower on a table
saw (arrow 2), which is fastened to a full-width 2x4
(arrow 1) to
create the "L"-shaped profile.
The idea here is to simulate the lower sash
of a traditional wood-sash window |
|
| I set the air
conditioner in the opening to test the fit.
That bare unpainted piece of wood is just the
right height to catch the flange on top of the
window air conditioner. |
 |
|
The A/C unit could not fall out, but it
would not sit level because the bottom wanted to slide
inwards.
Later, a piece of wood fastened to the sill,
(below the air conditioner) will secure the unit in place and keep
it level.
 |
Next, I removed the air conditioner and
installed a thin piece of plywood on the inside
to keep bugs out. Then I primed and painted
all the outdoor parts. Even though all the
exterior window trim on my house is painted
white, I decided to paint this trim the same
green as the house to de-emphasize the A/C
opening. |
|
| I built a
2-piece cover for the air conditioner opening. I
made the outer cover from 1/2" plywood, cut to a
size that left a 1/8" gap all around the edges. From the
outside the A/C opening is not overly
conspicuous... it almost blends in with the
siding. |
 |
|
 |
The inner part of the cover panel was made from
another piece of 1/2" plywood attached to a
frame of 3/4" thick wood and capped with a piece
of Lauan plywood, which is less than 1/4" thick.
I filled the cavity with foam insulation, then I
primed all the bare wood and applied
self-adhesive foam tape to the edges of the box
to act as a gasket. |
|
| From the
inside, the cover panel looks like this. The two
sections are held together with 4 long screws,
driven from the inside.
Related Article: Building A Cover For The A/C
Opening |
 |
|
But Wait... It's Still Summer... What
About The Air Conditioner?
After the covers had been built and fitted
to the opening, I removed them and returned to the most important
task... installing the window air conditioner.
I wanted to complete the covers because I
knew that later in the fall, when it's time to remove the A/C, I
wouldn't have the inclination to dick around with building
the covers. And I would be battling cold weather, since I never seem
to get the A/C removed until late October.
 |
I set the window air conditioner in the opening
and slid the bottom hold-down board under
the front of the A/C unit. Then I drove in 2
long deck screws (red arrow) to hold the board
in place. Note how there is a small piece of
thin plywood to the left of the air conditioner.
This filler block was necessary so I could screw down
that plastic accordion-like side screen. |
|
This board is just a piece of 2x4
that I ripped narrower on my table saw. In my case this
board was about 2 inches wide. This board basically
simulates a window sill. If you really analyze a typical
window air conditioner, the weight of the unit pushes out
at the top (pushing against the bottom edge of the raised-up
window sash) and pushes in at the bottom, (pushing
inwards against the window sill).
In this project my approach is essentially
to simulate the window sill and the lower edge of the window sash.
Normally, when installing a window air conditioner, you raise
the window sash high, set the A/C against the sill, and lower
the window sash so the A/C's top flange pushes against it. But you
can't raise and lower the "simulated sash" when installing an air
conditioner in a simple hole in the wall, so a different approach is
needed.
Consequently, the simplest way to hold the
air conditioner in place is to install a removable sill that
the A/C unit can push against.
| Since those
plastic accordion-type side extensions are
pretty useless at sealing air leaks, I cut out a
piece of 3/4 inch rigid foam insulation to fit
around the case of the air conditioner. This
made a big improvement at sealing the unit from
air leaks. It might also be a good idea to caulk
around the foam insulation with Seal-N-Peel
removable caulking. |
 |
|
 |
From the outside it looks like a window air
conditioner without much window. I like this
method of installation because it's not too
obtrusive. Being on the second floor, many
visitors to my house have not even noticed this
A/C unit hanging out the wall, even though it's
just above the back door. |
|
More Info:
|
|
|
- Basic
Carpentry Tools
- Circular Saw
- Miter Saw
- Table Saw
- Cordless
Drill/Driver
- Cordless Impact Driver (Optional)
- Pneumatic Finish Nailer
- Reciprocating Saw
- Fein® Multi-Master (Optional)
|
Materials Used:
- Azek® Cellular PVC Trim Boards
- PVC
Cement
-
Lumber, 2x4, miscellaneous
- 1/2"
Premium Plywood
- Foam Insulation
-
Caulk
- Finish Nails
- Shims
- Primer
- Exterior Paint
|
|
|
Related Articles:
|
Web Links:
|
|
|
|
|
|
|
|
|
|
|
|
