Commonly Used Replacement Window Installation Methods
The drawing to the left shows a typical
aluminum framed new construction window
installed in a wall with lap siding.  The red
dashed line indicates the path of rain water
being diverted away from the window.
Vinyl Replacement windows for residential and commercial buildings are becoming
increasingly popular. Among their many benefits they provide increased comfort,
updated looks, and energy efficiency. Installation of these windows, however, if not done
properly, can result in
severe damage caused by water seepage into the interior walls of
the structure. Current installation methods include, but are not limited to the following:
Method #1.   The exterior siding around the
perimeter of the window frame is cut away to
expose the nailing fin that holds the window
in place.  This old window is then removed
and a new construction style (nail fin frame)
window of the same width and height is
installed.  A filler board is used to replace the
cut away siding and 1x4 trim boards are
typically installed to hide this cut away area.  
The red dashed line shows a possible path
for rain water if the caulking is not properly
installed or fails for any reason.
Method #2.   Leaving the old aluminum
window’s main frame in place, the new
window is sized to fit inside of the old frame
and is sealed in place with caulking between
the old frame and a flush fin on the new
window. The red dashed line again shows a
possible path for rain water if the caulking is
not properly installed or fails for any reason.
Method #3.  aAfter complete removal of the
old aluminum window, the new window is
sized to fit inside of the sheetrock and
framing and is sealed in place with caulking
between the exterior siding and a flush fin on
the new window.  The red dashed line again
shows a possible path for rain water if the
caulking is not properly installed or fails for
any reason.
The preceding methods as well as most others, rely on caulking as a primary seal to
prevent water from seeping into the structure.  Deterioration of the caulking, cracks
in the adjacent siding, improper caulking application and other factors can lead to
failure of this seal and water seepage into the walls of the structure.
Our Patented Window installation and flashing system diverts water away from the
interior or the wall without relying on the troublesome caulking that other methods
do.
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