Window Fitters Guide to Window Installation 
70                ©2022 AWDI, LLC Do not reproduce without permission
Depending on the condition of the opening and the
type of exterior trim or siding, it may be necessary 
to cap the opening to make a smooth transition of
outer and inner surfaces in preparation for the new
window.  At least cover or caulk all cracks and holes.  
Wood furring can be used to fill gaps in between 
siding and interior walls and to provide structural
support in the opening.
Most openings will now be ready for the installation
of exterior "blindstops".  Aluminum or vinyl angles
(1” x 3”) or wood (1” x 1” or 1” x 2”) can be used for
stops and should be installed to the outside allowing
for depth of replacement window (3 1/4”).  Install
these stops on head and both jambs only.  Sloped
sills require the use of the provided sill angle.  
Flat sills should be caulked where the window 
meets the sill so as not to block drainage.
Install new window against outside stop, caulk and
trim interior and cap exterior as necessary.  It may
be wise to cap the furring or outside stop before
installation to minimize after-installation trim work.
Pre-extruded shapes or available “Snap-Trim” can
make the job easier.  Mount the angle of the snap
trim with “pop rivet” to the top of window.  After
placed in opening, mount angle to other sides.
Plumb and square window using snap-trim angle
and pop rivet to window and screw trim angles to
interior window opening, cap exterior and caulk.
Once all trim angles are secure “Snap Over” trim 
and caulk.  The use of Snap Trim eliminates the 
need of stops and shims.
NOTE: When removing finned windows it is possible
to tear the underlying building paper and weather
barrier. If so, consider a “Jump Frame” installation
described elsewhere in this manual.
Three
Installation
Methods
SAMPLE MANUAL

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