Coastal CMU Installation with Flush 2x8 Buck
Window Fitters Guide to Window Installation 
131                ©2022 AWDI, LLC Do not reproduce without permission
2 x 8 Step 3:
Using flexible, 
adhesive-backed 
flashing, create a sill-
pan by applying the
flashing along the sill
and up the sides
approximately 6 inches.
2 x 8 Step 1:
To flush mount a
finned window use
2”x8” pressure-treated
buck material fastened
to the block with code
required fasteners
properly embedded into
the block.
Apply bedding sealant
to the block to seal the
buck against the block
when installed. Seal all
four corner joints.
Exterior
2 x 8 Step 2:
As with recessed
mounting, treat the
masonry opening with a
CMU sealer for the 
purpose of sealing the
CMU window cavity
from absorbing liquid
water.  
Be sure to cover the
buck, and the block  -
inside and out to a dis-
tance of approximately
9” out from the opening
in all directions.
2 x 8 Step 4:
Once the window is
mounted, flexible 
adhesive-backed 
flashing and  wire lathe
as needed to be sure
the entire exterior
perimeter is well sealed
to shed surface water.
Precast
Lintel
Poured
Sill
2x8 Buck
on All
Sides
Exterior
Exterior
Exterior
SAMPLE MANUAL

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