Replacing the Bathroom Window

The downstairs bathroom window (the one on the left) “before” from the exterior.

The downstairs bathroom is one of the rooms that we knew from the outset was going to be a full teardown and rebuild. One feature that we were keen on changing was the tiny window. It appeared to be one of the original windows from when the house was built. It was a 20″ by 32″ crank out window (seen above [and here from the interior]), on which the seals were broken causing fog between the panes. The window needed to be replaced anyway, so we thought it would be a good idea to upsize it in the process. Candidly, this was my first time replacing a window. But on a house with wooden siding where we had the interior wall down to the studs, it seemed manageable.

We chose a 36″ by 48″ sliding window by Jeld Wen from Lowes as its replacement. It has a vinyl frame with a half inch flange that attaches to the exterior surface of the plywood (or in this case OSB) wall. Since we wanted to increase the span, we were required to pull a permit. We already had a permit open for the deck, so I drew up a quick plan and filed it with the town. The plan actually proved to be very helpful for me as well, since it forced me to have all of the measurements written down ahead of time.

The first step was cutting the rough opening, which I did starting from the exterior with a skill saw. The skill saw cut through the siding and OSB wall, plus about halfway through the studs. I used a sawzall from the interior to finish cutting through the studs. I did all of this with the old window still in place and pulled the entire piece out in one shot from the interior with Britt’s help.

The rough opening from the interior, after removing the old window and header.

The rough opening from the exterior

The next step was to install a new header and stud frame on the interior. On the plans that I drew, I indicated that I would be doing a double 2×4 header. But when I was sitting with the code inspector, he pointed out that for this span, on a wall of this length the code required 2x6s. He also gave a very helpful suggestion of putting a piece of 1/2″ plywood between the 2x6s making the header width flush with the vertical 2×4 studs. I did have to cut an additional 1.5″ from the studs on the bottom of the opening to accommodate the sill plate. I also discovered that the house is very out of plumb. You can see from the photo below, the window opening is perfectly level, but the house runs downhill to the left. There is about a half inch of variance from the left to the right in the spacing between the header and the ceiling joists. Great job, guys who built this house!

The framed out rough opening with new header.

After I finished framing the interior, we popped the window into the opening to double check that it fit right. The next step was to remove the siding on the outside, so that the window frame could be seated directly onto the wall of the house. So I marked the cuts, an inch from the opening for the entire perimeter of the opening, then adjusted the skill to a 1/2″ cutting depth and cut away the siding.

Jake marking the siding to cut away (photo: Britt)

The rough opening after removing the siding

The next step was fastening the OSB to the framing with 1 & 5/8″ screws every couple of inches on the perimeter. I then did the same with the siding to make sure that it was totally snug to the OSB around the entire perimeter.

After that, we installed flashing tape. This was especially important, since the guys who built the house failed to put any moisture barrier like Tyvek between the plywood and the siding. As a result, there was some evidence of water damage around other windows and doors on the house.

Starting at the bottom, we put flashing tape on the bottom and sides of the rough opening. After this, we installed the window, shimmed it perfectly level and fastened it into place using the screw holes in on flange.

Fitting the window after installing flashing in the rough opening.

After the window was screwed into place, we put another layer of flashing tape on the entire perimeter, put a strip of Z-bar flashing on the top lip of the window and installed pressure treated 1×4 trim. After all of this, we caulked all of the seams with DAP 3.0 exterior sealant. In retrospect I would have used clear caulking, rather than white. The stuff is very messy and hard to apply with any sort of precision. On the interior, Britt installed spray foam insulation into the gap between the window frame and the studs. The photos below are the final product from the interior and exterior (minus paint). At the very bottom of the post, I embedded a timelapse video of the whole process shot from the interior.

A timelapse of the whole process (from the interior):

Replacing the Bathroom Window from Jacob Breinholt on Vimeo.

[All photos by Jake except as otherwise indicated]

Posted in Bathroom, Video.