Replacing Window in Bathroom
Step-By-Step Instructions on How to
Replace a Bathroom Window
By Mark J. Donovan
The double hung wooden window in our bathroom was nearly 20 years old and
looked every day of it. The spring mechanism for keeping the windows open had
broken and the only way to keep them propped open was to use a board to hold
them in position. The window panes themselves were hazy and the wood was water
stained and unsightly. And that’s just on the inside of the window. The outside
was even worse. The window sill was so severely checked and punky I could push
my finger through it if I tried. Consequently it was more than time to replace
my bathroom window.
To replace my bathroom window I first
removed the interior window trim and took some measurements. I measured the
height and width of the window frame and jotted the measurements down. I then
went to my local home improvement center and found a replacement window that met
the window frame rough opening measurements. I also chose to select a bathroom
window replacement that was constructed out of wood but had vinyl sheathing over
the exterior of it.
Due to the fact that the window I selected was meant for brick molding and the
type of exterior trim work around the existing window required a 3 inch molding,
I also purchased some 1”x4” select grade pine trim. I also picked up 8d
galvanized nails and 1-1/2 inch roofing nails.
The first step in actually replacing
the bathroom window was to remove the old one. It was a fairly easy process. I
removed the exterior side trim and then pried out the roofing nails that held
the old window flange nailing tabs to the house exterior. I also used a hammer
and nail punch to push through the finished nails that were holding the interior
sides of the window frame to the window frame wall studs (jack studs). I was
then able to remove the old window from the window frame.
To install the new bathroom window I first made sure the existing house wrap was
stapled down to the interior of the rough window frame opening. I then placed
the new bathroom window into the opening and used my measuring tape, level and a
few wooden shims to make sure it was centered, plumb and level.
Once I had the new bathroom window where I wanted it I fastened it to the
exterior house siding using a few 1-1/2 inch roofing nails. The roofing nails
were applied at the plastic nail tabs on the exterior of the window. I then
tested the window to make sure it opened and closed properly. Once I confirmed
the new bathroom window was operating smoothly I installed additional roofing
nails around the perimeter of the window. I installed nails every 6 inches or so
along the window perimeter.
After replacing the bathroom window, I still had to install the exterior and
interior window trim. I started with the exterior trim. First I primed and
painted the 1”x4” select pine lumber and let it dry. Then I measured and cut the
pieces to the proper length and widths and touched up painted the cut edges.
I installed the exterior trim starting at the bottom and working my way upwards.
In this particular window replacement project I only needed to install side
rails and a top piece, so I installed the side rails first.
Before nailing the side rails into place I also installed two small pieces of
Z-strip flashing on the house siding. I installed them just underneath where the
side trim rails would go, so that any water that dripped down the exterior trim
side rails would not wick underneath their bottom edges and behind the house
I then installed the top exterior window trim piece. With this piece of exterior
trim piece I installed a length of Z-strip flashing over the top edge of the
trim and underneath the house siding. I fastened the exterior trim pieces to the
house sheathing using the 8d galvanized nails. I then caulked around all the
For the interior window trim, I wound up returning to the home improvement
center and buying window stool and 2-1/2 inch window casing molding. Again, I
stained the pieces first and started from the bottom installing first the window
stool, followed by the bottom apron. I then installed the interior window trim
side rails followed by the top piece. Installing interior window trim takes a
little more skill and a miter saw, and a coping saw. I used 6d and 8d finished
nails to fasten the interior window trim to the wall. I also used a number of
When installing the window trim it is best to initially tack the trim pieces
into place with only a couple of nails and do not sink them. Once the entire
interior trim has been tacked into place and looks good you can then go back and
add more nails and sink them with a nail-punch and hammer.
For information on
Installing a New Window, see the
Installing a New Window Ebook from
HomeAdditionPlus.com. The Installing a New Window Ebook provides easy to
understand, step-by-step instructions, on how to remove an old window and
install a new one. Pictures are included for every key step in the process.
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