Window Fitters Guide to Window Installation
121                 Contents ©2022-Do not reproduce without permission
6. Finishing and Trim
Do not cover more than 1/2” of the window frame 
on any side allowing clearance of 1/2” from all 
materials, operators and hinges, etc.
The clearance between the window frame and the
rough opening to which the window is anchored
should be between 3/8” minimum and 5/8” 
maximum.
If slow expansion foam tape 
is used on all 4 sides, 
no other sealant or insula-
tion is necessary - on the
inside or the outside. You
may use sealant to finish 
the trim if you wish.
If no slow expansion foam
tape is used on any side, 
sill, or header, then low
pressure PU foam sealant
can be injected between the
window and the rough open-
ing, and finished with backer
rod and sealant as required.
OPTION 2-
Seal Outside 
and Cover 
with Trim
OPTION 1-
Seal Inside
with Low
Expansion
Spray Foam
where Foam
Sealing Tape
is not used,
and cover
with 
Sealant if 
needed.
OPTION 2-
If foam sealing 
tape is not used, 
fill gaps with 
Spray Foam 
and cover with
Sealant.
Insulation
Backer Rod
Sealant
Insulation
Backer Rod
Sealant
Insulation
Backer Rod
Sealant
SAMPLE MANUAL

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