Window Fitters Guide to Window Installation 
69                ©2022 AWDI, LLC Do not reproduce without permission
Replacing Aluminum 
Windows
The first consideration for replacing aluminum 
windows is how to accommodate the probable 
difference between the frame depth of the typical 
aluminum window frame (2-3/4”) and the typical
vinyl replacement windows (3-1/4”). Then, if the 
aluminum window is mounted with a nailing fin, 
the probable frame depth behind the fin is approxi-
mately 2”. Throughout this manual are techniques
and examples of handling these discrepancies.
Aluminum windows are usually secured by 
fasteners through the exterior flange into the 
plywood sheathing or wall studs.  Also fasteners can
be mounted through the jamb (in the sash channel) 
into the wooden frame around the opening.
This method works well when the old window is care-
fully removed. NOTE: For an alternative method of
replacing an aluminum or other finned window, go to
Alternative Method of Replacing an Aluminum Window
in this manual.
Most aluminum window frames can be pried up and
out of the opening without disturbing the siding or
interior finish.  Begin by removing the operating 
sash from the window.  If there is a fixed panel,
remove glass carefully.  In windows with fixed pan-
els, the glass may need to be broken to remove it.
Use nylon filament tape in a criss-cross pattern to
minimize shattering.
Remove all visible screws in the window jambs.  If
this does not free the window, use a flat putty knife
between the window frame and the internal jamb
trim to locate the flange screws.
Using a cold chisel or putty knife, attempt to shear
all the mounting screws between the flange and the
side of the house.
Note: The drawings are typical installations.  
Though not to exact scale, they are representative 
of most situations and are meant as a guide only.
Once all fasteners are sheared or weakened, carefully
pry up the bottom frame using a block under the pry
bar to protect the inside sill.  If fasteners can’t be
sheared or weakened, careful prying can remove the
window.  Protect the opening as much as possible to
minimize damage to siding or interior finish.
Once the bottom frame is arched sufficiently, use 
a recipro-saw or hacksaw and cut the frame piece.
After it is cut, gentle use of the pry bar can remove
both sides and top of frame without disturbing the
siding or interior jamb, head, or sill trim.
Old
Aluminum
Window
Replacement
Window
SAMPLE MANUAL

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