Replacing Windows in
Concrete Block and
Stucco (CBS)
Applications
Replacement applications in Coastal Regions will be for
windows installed in block walled homes with Stucco 
finish, and standard wood frame constructed homes with
vinyl, wood, aluminum siding or brick or other masonry
veneer finish.
There are unique conditions for stucco over wood frame
and stucco over concrete block construction. Some 
conditions of stucco finish on wood frame are covered in
the “Jump Frame” section and applications where the 
stucco is cut back removing a window with brick mould
and the new product is installed with a wood block
installed over the mounting fin of the new window and 
the resulting assembly is installed in the opening and
sealed to the remaining stucco finish.
The conditions and instructions covered here will apply 
primarily to building constructions considered CBS
(Concrete Block Stucco) and wood frame with similar 
stucco finish.
Stucco covers the edge of the Old Window
Because the original construction had the stucco finish
applied after the window or door was installed, the stucco
often will partially cover the flange of the old window. This
creates problems that must be dealt with: Measurement,
Removal of the Old Window, and Finish of the New
Window. 
1. Measure- It is difficult to measure for the new window
because so much of the old window can be hidden behind
the exterior stucco finish and the interior wallboard and/or
sill finish. The new window cannot be too large or too
small, for obvious reasons. The success of the job can 
be made or broken with proper measure or improper 
measurement.
2. Removal of Old Window- When removing the old 
window, it is problematic because the stucco needs to 
be kept out of the way of the removal, but damaging the
stucco can require costly and difficult stucco repair, 
which almost never can be matched to the old finish – 
making for an unsightly exterior finish. The interior 
wallboard and sill, if damaged, can also require difficult
and costly repair and/or replacement of components.
3. Finish of the New Window- Once the new window is
installed, the exterior needs to be finished to create a
weather barrier that repels entry of water, moisture and
air, and the interior needs to be returned to a decorative
state as good or better than existed with the old window.
The mistake too often made is to order a window too small
for the opening, and/or ordering a window that needs the
mounting flanges cut off in order to make it fit in the 
opening, but rendering it impossible to properly seal it 
on the outside and trim in on the inside.
Window Fitters Guide to Window Installation 
134             ©2022 AWDI, LLC Do not reproduce without permission
SAMPLE MANUAL

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