The following 
techniques are
designed to allow
proper 
measurement,
proper removal of
the old window, 
minimization of
opening damage,
proper preparation
of the remaining
opening, proper
mounting of the
new window to
meet applicable
codes, and proper
finishing of the
newly installed
window in a
weather tight and 
architecturally
acceptable fashion.
How to Measure
Understanding how the old window was mounted will help
make proper measurement possible. The diagram shows
typical mounting in block and wood frame. Both utilize
some form of wood “buck” either a full buck or wood pieces
used to approximate the function of the “buck” which is to
make amounting surface to which the window can be
mounted, while allowing the ?” surrounding flange projec-
tion to butt against it effecting an overlap perimeter joint..
Allowing for an approximate 1/8” to 3/16” shim space, the
actual opening (hidden behind the exterior stucco and 
interior wallboard, sill, trim or caulk seal) up to 1” larger in
height and width than the exposed window might indicate. 
Ordering a new window based on that assumption would
create a problem putting the new window in the opening as
it must be placed in the opening from the outside to allow
the flange to overlap the “buck” for a proper weather seal.
The AWDI method of window removal and install prescribes
proper measurement as shown. Measure from the inside of
the wallboard on the right to the inside edge of the wall-
board on the left. Measure from the upper inside edge of
the wallboard to the sill. Subtract 1/2” from the width and
height dimensions, and then add 1” to each.
Therefore, a measured width of 34-3/4 will result in an
ordered flange tip-to-tip Width of 35-1/4” (34-3/4, minus
1/2”, plus 1”). A measure height of 56-1/8” will result in an
ordered flange tip-to-tip Height of 56-5/8” (56-1/8”, minus
1/2”, plus 1”).
While it may seem simpler to add to the measurements,
this method allows for some adjustment for irregular 
situations. The 1/2” deduction is for the shimming. 
The 1” addition is for the flange (1/2” protrusion on all 
4 sides). If, after analysis, it is obvious that the shimming 
is a great deal more or a great deal less, adjustment can 
be made. If the sill is a ?” thick stone sill, modest 
adjustment in the ordered Height can be made, as well.
Bottom Line: The method of measurement will product 
the best possible chance to install the new window with 
a minimum of damage to the existing opening, and a 
minimum of repair; and allow proper weather-sealing.
How to Remove the Old Window
Remove any of the operating panels or sash.
The exterior stucco finish must be cut back to the
edge of the flange. This is possible to do with a Fein
oscillating tool and a masonry blade. Carefully deter-
mine where the flange edge is on all 4 sides. Using a
framing square or other straight edge, cut the stucco
to the flange tips on the top, bottom and sides. You
should be able to get a clean cut with no damage.
Next, using the Fein
oscillating tool and a
sealant blade, free the
window on the inside
from any caulked or
sealed joints on the
sides, top or bottom.
Remove any of the
operating panels or
sash.
Tape any remaining
glass panes, and
using the Fein oscil-
lating tool, remove
the glazing beads,
glazing compound,
and glazing adhesive
and carefully remove
the stationary glass pane(s).
If there is a mullion
or other separating
piece, if possible use
the Fein oscillating
tool to cut it free from
the window frame.
Remove the inside sill
(if any).
Remove all 
mounting screws
from the window
frame.
If possible, cut the
side frame pieces
through to release 
the frame from the
opening.
Window Fitters Guide to Window Installation 
135              ©2022 AWDI, LLC Do not reproduce without permission
Step 1.
Remove all 
Frame and
Glass
Step 2.
Remove 
Anchoring
Screws and Cut
Perimeter Seal
SAMPLE MANUAL

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