The Contractor's Guide to installing Vinyl Windows                            46              ©2022 AWDI, LLC Do not reproduce without permission
Step 5:
Accommodate
drainage from the
sill. Install a “Sill
Pan” with a back
dam overlapping
the jamb flashing -
before installing
new trim to form
the “Blind Stop”.
If you’re not using
a pre-formed sill
pan, you can 
create the effect by
installing a 1 x 2
to create a back-
dam before apply-
ing the flashing.
Step 6:
It is important to
install a drip cap
along the top of the
header exterior trim
as shown. 
If J-Channel is
needed instead,
install it along top,
and jamb sides.
Make sure the top
lays over the jamb
pieces and that the
sill piece fits
between the jamb
pieces for proper
drainage. 
Step 8:
Place a bead of
caulk on all 4 sides
of the inside surface
of the exterior trim
that extends into
the opening. 
Leave two 1 inch
gaps along sill to
allow drainage. 
Step 7:
Cut new exterior
trim wider than the
old trim so that it
projects into the
opening 3/8” on 3
sides.
Use of cellular uPVC
trim boards for
weatherability 
is highly 
recommended. 
Confirm the new
trim projects 3/8” 
to the interior on 
three sides - creating
an effective “blind-
stop” for the pocket
install. 
SAMPLE MANUAL

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