| In
This Article:
After a new construction
window is installed, flashing is applied and a custom sill is
installed beneath the window. Side and top casings are
installed. |
Related
Articles:
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| Skill Level:
3 (Intermediate) |
Time Taken:
About 3 Hours |
By
Bruce W. Maki,
Editor
 |
As part of a bathroom remodeling project,
the owners of this old house wanted a window moved over
a couple of feet. The old window was to the left of the
new one, in the spot that has been patched with plywood.
I had to remove about 5 rows of vinyl siding to
expose the area that needed work.
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| This is an Andersen 400 Series Tilt-Wash
double-hung window, purchased at Home Depot. |
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When I installed the window I applied a
large bead of caulk around the rough opening, which you
can see as a whitish smeared mess next to the gray
nailing flange. |
|
Window Flashing:
| I applied a strip of Grace Vycor® Plus
rubberized asphalt flashing material across the bottom
nailing flange. |
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|
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Next I applied strips of flashing up the
sides... |
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| ...and then across the top flange.
Note the missing section of bed molding, just above
the window. I had to cut the molding to work on the
window framing. I'll replace that later. |
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|
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I made the top flashing fold over onto the
top surface of the window frame. This should be better
at keeping stray rainwater from getting behind the
window. |
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| I made this sill from two pieces of Azek
glued together.
The material was about 2½" wide and cut with a
10 degree bevel. |
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|
 |
I pre-drilled four mounting holes in this
36 inch long sill.
First I drilled a 3/8" hole about one-third
of the way through. This hole needs to be wider than
the screw head. |
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| Then I drill a smaller hole (3/16", I
think) all the way through the sill. This hole needs to
be about the diameter of the screws. |
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|
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I placed a deck screw head into the hole
to be sure it would fit.
This is a 4 inch deck screw. I've also used 3 inch
deck screws, but I needed to drill that large hole about
2/3 of the way through. |
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| I applied a bead of caulk to the back edge
of the top surface. |
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|
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Then I pushed the sill into place
underneath the bottom frame of the window.
I made sure the sill protruded an equal amount on
each side (about 3½"), then I drove in the 4"
deck screws to fasten the sill to the framing. |
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| The sill after I mounted it to the wall. |
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|
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A close up of the bottom corner. Note how
the caulk oozed out from under the window frame. This
tells me that I used enough caulk. |
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The Side Boards:
 |
The window nailing flange is about 1/8
inch thick, and it creates an irregular surface for the
casing boards. To make a more even surface, I nailed
some strips of foam sill seal insulation next to
the nailing flange.
Note that the word "sill" refers to the
sill plate, the piece of wood on top of a
concrete foundation, and not a window sill. This foam
gets compressed very thin beneath the weight of an
entire house. |
|
This insulation comes in long rolls, so it's not worth buying
just for a few windows. Other materials should work just as well,
such as 1/8" hardboard (often called Masonite).
| I dabbed some Azek adhesive to the bottom
edge of the side casing boards.
The side casing pieces were ripped to 3½" wide,
and the bottom end was cut at a 10 degree bevel to match
the 10 slope of the window sill. |
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|
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To avoid getting glue all over the sill, I
placed the side casing next to the window and carefully
slid it down on top of the sill. |
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| I fastened the side casing using 2½"
finish nails. |
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|
| Then I drove in some 2½" stainless
steel siding nails. These are thin ring-shank nails with
small heads. They hold viciously, and the small heads
are well hidden after painting. |
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|
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I placed the top casing into position and
applied some glue. |
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| And I nailed the top casing. |
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|
Note that plain old PVC cement for plumbing pipes can also be
used... but since it dries faster it gives you less time to position
the materials.
 |
Another view of the top casing. There is a
slight gap between the side and top casing boards, which
I later filled with caulk. |
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| I replaced the missing section of bed
molding. I caulked all the gaps and joints. |
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|
Plugging The Sill Mounting Holes:
 |
Using a 3/8" plug cutter bit mounted
in a drill press, I made these small plugs from a scrap
of Azek.
I dabbed some glue on the plug while I held it with
pliers. |
|
It is possible to use a plug cutter bit in an ordinary drill, but
it getting the cutter started is no fun. The bit walks all
over the place until you get the perfect angle of attack, and then
it cuts properly.
| Keep a firm grip on the plug, I jammed it
into the hole.
Note that the broken end of the plug is out,
and the flat end (which was the top surface of the board
as I cut the plugs) goes in first. |
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|
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I tapped the plug with a hammer. It's best
not to drive the plug in too deep, because then
you won't be able to sand it smooth. |
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| After I inserted the plugs I let the glue
dry for a full day. |
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|
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The next day I used a belt sander to sand
down the plugs and smooth out the saw marks on the sill. |
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| After sanding, you can barely see the
plugs. |
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|
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The sill looked very smooth after sanding. |
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| The window sill had sharp edges, so I used
a paint scraper to "break" the corners.
This is a simple process, but needs explaining. The
best way to break a sharp corner is to pull the scraper quickly
down the length of the material. It's difficult to start
exactly at the end, so I start a few inches in and
scrape to the far end, then I come back and pull the
other direction to complete the cut. |
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|
I can do this with any sharp metal edge: a knife blade, a
chisel... heck I could probably do this with a hockey skate.
| The window casing after completion. Now
the siding needs to be patched up. |
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|
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I caulked between the old wood
siding and the new window casing.
Normally this is how my window casing would meet the
siding. But since this house has vinyl siding over
the original wood siding, I need to match the methods
used around the other windows.
The vinyl siding J-channel actually overlapped
the casing slightly. That's not my preferred method, but
I needed to remain consistent with techniques used by a
previous siding installer. |
|
| The window area after the siding had been
replaced. |
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|
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This is another window on the same house.
Since there was enough headroom over the window, I was
able to make a small "lookout" piece of trim
above the top casing.
The old vinyl siding was removed on this entire wall
and replaced with new siding (because the old siding had
faded badly). This allowed me to do the job properly,
meaning that the J-channel butts against the casing,
rather than overlapping the casing. |
|
| This is a closer view of the
"lookout". This is like a miniature water
table trim... it has the same 10 degree slope. |
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|
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| I made
this simple CAD drawing to (approximately) describe the
top casing used over the double window above. The single
window featured in this article couldn't employ this
type of top casing, because the window was so close to
the roof.
These dimensions were taken from the casing on the
house I live in, not the house shown in this
article. This top casing was used with 4 inch wide side
casings, in this article I used 3½" wide casings.
This drawing shows an 8 degree slope, but the article
mentions a 10 degree slope. I used whatever angles I had
already cut on my table saw.
You can use any width you want for exterior window
casing, though it may have a (subtle) impact on the
overall appearance of the house. |
|
Finishing:
A few days later I applied a coat of 100% acrylic exterior paint
to the Azek trim. No primer is needed because the paint doesn't soak
in.
|
Tools
Used:
- Cordless Drill/Driver
- Table Saw
- Miter Saw
- Basic Carpentry Tools
- Finish Nail Gun
- Belt Sander
- 3/8" Plug Cutter
|
Materials Used:
- Azek Cellular PVC
Trimboards, 3/4" Thick
- Stainless Steel Siding
Nails, 2½"
- Azek Adhesive
|
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