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Insulation Project: Convert 2x4
To 2x6 Walls For Additional Energy Savings
In the climate where we live, wintertime temperatures are often below zero.
The 2x4 walls of our 40 year old home are insulated with a rock wool-type
insulation that performs poorly. As a result, our home is very cold and
uncomfortable. In one room, we even had mold in the walls due to
condensation within the insulation.
In the summer of 2004, I redid our boys' room and the result was a nice
looking room that was very comfortable in the cold temperatures due to the new 6
inch walls. For an overview on that project, go to
The project went so well that I decided to redo additional rooms.
This article deals with all the details of the next room I reinsulated, with a
few more details and pictures included.
In the small room shown on the left, there is one small awning window on the
exterior wall. Our goal was to replace the window with a long, double hung window to allow more
fresh air, light and space for a bunk bed for our two girls. It took a bit of
planning to make sure the window and bed set would both fit in.
obtain your window before starting the job. I found a window outlet, Walsh
Windows, that manufactures and sells windows locally. I was very pleased with
their staff and service.
Take off the trim...
planning, your next step is to remove the trim on the exterior walls and the
walls adjacent to the exterior wall(s). Use a knife to score the paint line
along the edge of the trim to minimize damage to the walls. Then gently pry
up the trim. I used a taping knife to start lifting the trim and then used a pry
bar. Try to not crack the trim or damage the interior walls and you will save a
lot of work when you reapply the trim.
To remove the nails from the trim, don't hammer them out... pull them
through the back with pliers. You will do a lot less damage to the trim!
down the drywall and old insulation...
After removing the trim, take the drywall down as shown on the left. You will need a hammer, pry bar, protective glasses, gloves, and a dust mask.
I find the best way to handle the debris is to break it into small pieces and
place it in large heavy-weight garbage bags. This is a dusty job so don't skip
the dust mask! Once the drywall is down remove all insulation between the studs. Remove all nails
and screws from the now bare studs. (If you notice any condensation or
dampness within the walls or on the insulation, allow wall to dry thoroughly
A good tip: Use a utility knife to score the drywall on the vertical corners where the piece meets an
interior wall and/or at the ceiling so you don't tear the paper and give
yourself more work!
Heating ducts may need to be moved...
If you have heating ducts located on the floor close to the old wall, they
may need to be moved (2" in my case). To accomplish this, cut out a (2")
portion of the floor so the heat duct can be moved. I used a combination of a
jig saw, circular saw, and reciprocating saw to cut this piece out. After the
piece is cut out, you will need to shorten the duct pipe (if you have forced
air) by the same amount.
If you have hot water heat, you may need to call in a plumber to
help with this task.
New window installation...
Since you have the room torn apart anyway, it may be a good time to consider upgrading your windows!
The easiest option is a "replacement window". Installation is simple for a
do-it-yourselfer, and involves removing only the
window sash since replacement windows utilize the old window frame, exterior
trim & molding. The actual window (slightly smaller than the
original) is installed within the old frame. You
can also choose to install a complete window that has nailing flanges that
will (hopefully) fit in the space left by your old exterior molding when you
Because I wanted a larger and differently-shaped window, I had a larger
project which involved cutting studs,
replacing exterior sheathing and siding and reframing the window (see diagram below
right). This last option can add days to the job, but I feel it was well worth
I used an expanding foam made especially for windows to seal the area
containing the shims around the window frame. I like this foam product because it not only provides a
weather tight seal but also provides structural support. Be sure to get the right foam -
expanding foams not made for window/door frames can produce so much pressure
they can actually distort the window!
If you don't have enough outlets, now is the time to add them. I had an
additional wall outlet installed as shown in the picture below. Drill holes for
the new wire with a 5/8" cutting bit - make sure the holes are set at least 2"
back so no future screws or nails fastened into the wall can hit the wiring.
Make sure the electrical breaker or fuse is removed or flipped off before the
outlet is installed.
(Note from NH: When doing renovations, you may be required
to update ALL the wiring in the room to current standards. This may
include replacing wiring, adding additional outlets and more. It's
always wise to check with your local building inspector or an electrician before
beginning the work.)
Install 2" Furring Strips
will need to saw 2x4's down to a 2" width (or whatever is needed) so your
finished wall will be 5 1/2 inches, the actual thickness for 2x6 walls. Measure
your existing two by fours. In some older homes they will be 3 3/4" or even 4"
instead of the 3 1/2" of modern 2x4's. You will need a table saw to rip the
2x4's down to the needed width and nail the furring strips onto the
existing 2x4's to provide a fastening surface for your drywall (or whatever wall
finishing product you use). I used 16d coated sinker nails along with a few 20d
coated sinkers on each piece.
If you have areas (like the header area shown to the left and along doubled
up 2x4's) where there is a 2" pocket after applying the 2x2 strips, you can
maximize the R-Value by filling the pocket with 2" rigid foam rather than
fiberglass batts. Also, after applying the foam, I used silicone caulk to
seal up any cracks.
Add Nailers If Needed
For the room on this page, I applied drywall horizontally rather than
vertically. This is the "standard" way drywall is installed when the studs are
16" center-to-center. Since my studs were 24" on center, this left a near
2-foot gap on the edge of two sheets. This would have led to a very unstable
To solve this problem, I fastened a horizontal nailing piece that
was centered at the 48" mark to accommodate the edges of both 48" sheets
(picture below). You should also check to make sure you have the needed
fastening surfaces for all your pieces of drywall or other wall covering.
Insulate With Fiberglass Batts
Install the fiberglass insulation. I used unfaced insulation batts which I
then covered with a plastic moisture barrier - the unfaced is a lot easier to
custom fit to odd spaces and the plastic is probably a lot better barrier than
what is offered with faced insulation. Also, tape all edges of the moisture
barrier with a good quality duct tape or red insulation tape.
Install the drywall...
I placed the sheet on horizontally so there would not be a joint at the
bottom or top corners of the window. For windows in cold weather homes, the
drywall will often crack at the bottom and top corners of the window if there is
a joint. I attached the bottom sheet first. I laid a bunch of shims on the floor
near the wall to keep the sheet off the floor a little, leaned the sheet against
the wall and marked the window opening.
I also used a handy trick to get the outlets cut out near perfectly. I
dabbed some ketchup on a paper towel and then blotted the outlets (below center
graphic). When I leaned the drywall against the outlets they left perfect
imprints on the back of the sheet! (shown right) I cut out the openings of the
bottom sheet and attached it. I then attached the top sheet and cut out the
window opening with it on the wall. Note that some will argue that you always
place the top sheet up first to support the ceiling piece - in this case the 2x2
supported the ceiling piece.
Tape and Finish Drywall
I taped and finished the drywall with one step for imbedding tape (shown
above right), and 3 additional coats over the top. Taping and finishing drywall
can be challenging but you can get some nice results if you know a few basics.
You want to apply light coats and level out your surface in between coats with
your taping knife. Avoid any sanding until the very end and then only sand
lightly. For a complete beginner's tutorial on taping and finishing drywall,
check out DrywallInfo.com.
Prime and Paint
You need to prime the drywall surface (below left) and then place one or more
coats of the desired color of paint. This is a good opportunity to repaint the
entire room. After painting, this would be a good time to refinish wood floors
if you have them.
Reinstall the base trim...
If you are using your same trim, you will have to shorten the base trim on
the adjacent walls by about 2 inches. You should measure to get the exact
length. Be careful not to cut off too much! You will also have to replace any
heat duct covers. (Above right.)
You will have to reinstall the window trim or cut new trim if you installed a
new window like I did. I like the natural pine look so I made my own window trim
and sill out of 1x4's, 1x6's, and 1x8's. This is a very economical way to go.
You can also obtain wood products to finish the window from the window dealer,
lumber yard, or home store.
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