When retrofitting Vinyl Replacement Windows in
an existing stucco finished opening, it is important 
to remove the old metal window protrusions to a
point where the old window is flush with the interior
drywall return.  The new window should be fitted
with an exterior trim piece (either integral or snap-in)
that extends over the existing exterior stucco finish.
The illustration below shows the new window,
placed in the old opening, and how it is to be caulked
and sealed both inside and out. This is commonly
called a “jump frame” installation.
Remember the following:
1. The Frame should be anchored to structural
framing with screws.
2. Screws shall be minimum of #8, non-corrosive.
3. Screws shall not be placed in fin.
4. Retrofit window frame shall not be attached to
the old window frame.
5. Fin shall not be installed over lap siding.
6. Elastomeric (see caulking section) caulk shall
be installed
- Between the fin trim and exterior wall
surface (stucco) and,
- Around the perimeter of square-edged fins
7. The sealant bead shall be continuous except for
small gap(s) near center of bottom fin (for
drainage)
8. Unlike materials shall not be placed in contact
with each other.
When the old window contains a fin and is mounted
under exterior casing, as is also common in stucco
over wood construction, the exterior casing can be
removed, and the old finned window removed 
without disturbing the weatherability of the 
underlying construction.
Care to prevent
Water Intrusion
The wide flange will
cover the old window
and overlap the 
exterior stucco. 
It is difficult to 
construct a drip cap
over the flange.  Too
often water 
will run down the
outside of the wall
and down between
the flange and the
wall and eventually
cause problems.
Vinyl Replacement Window in a Jump Frame Stucco Application
Jump-Frame Sill Details w/ applied leveling Block
Window Fitters Guide to Window Installation 
74                ©2022 AWDI, LLC Do not reproduce without permission
Installing Replacement Vinyl Windows in Stucco
Note: Block to Level old
Sill provides Support. 
It can be made out of
lumber or cellular PVC
SAMPLE MANUAL

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