Window Fitters Guide to Window Installation
119              ©2022 AWDI, LLC Do not reproduce without permission
4. Prior Weather Sealing
All Flashing should be done prior to mounting the
new window. Install proper flashing on all four sides
wrapping the header and jambs and sill. The sill
flashing should be in a sill pan fashion with side and
back dams to direct water to the outside.
The recommended method of flashing the sill would
be with slow expansion compressed sealing foam.
The foam should be placed on the sill with cut-outs
for the capture blocks as shown.
The slow expansion foam can be used on the jambs
and head and can be installed prior to installing the
window into the opening, or placed in the gap once
the window is set in place. It should be placed into
the gap along the header and jambs from the outside
to accommodate the jamb clips. The foam tape can be
left exposed to the elements or if recessed sufficiently,
can serve as backer rod for exterior application of
sealant.
Choosing to use spray foam will require accurate
application of foam beads in the header, jamb and 
sill gaps and backer rod on both the interior and
exterior. The sill gap needs to allow two places for
proper drainage to the exterior.
Wood
Framing
needs to be
properly
flashed
and with a
sill pan
prior to
mounting
the win-
dows.
Concrete
Block Wall
needs to be
sealed,
with proper
sill
drainage
before the
windows
are 
mounted.
Use a Wood
Surround
in a
Masonry
Opening,
properly
sealed with
flashing
tape and/or
foam 
sealing
tape.
Properly
flash the
opening.
Wrap the
header and
jambs with
flashing
tape and
use slow
expansion
foam seal-
ing tape
along the
bottom or 
a sill pan.
Similar to
Frame
replace-
ment, place
a wood
buck in the
opening to
cover the
left-in-place
remnants
of the old
window.
New Construction
Masonry
Wood 
Buck
Wood Frame 
Replacement
Masonry
w/ Wood
Buck
SAMPLE MANUAL

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