Making the
Decision
The decision to
install a replacement
window from the
“outside in”, against
the interior stops, by
removing the 
exterior stops,
requires more 
outside work, 
but this method 
of installation 
has many added
benefits:
1. The interior
stops don’t need to
be removed 
and replaced which
makes a better look-
ing installation since
there is no damage
to over-painted inte-
rior stops or mould-
ing, etc. The job is
cleaner and neater.
2. Since the exterior is to be re-finished in most
instances, there is a work savings by not 
having to remove and replace the inside stops. 
3. It is easier to brake and install capping to finish
off the exterior of an opening without a blindstop
than to cover an old blindstop. The capping looks
better, too.
4. Most Replacement Windows without head
expanders fit better against interior stops without the
1/8" offset of the material thickness of the expander.
5. The installation is more energy efficient and
requires no insulation stuffed into the head
expander..
6. More glass and egress area is possible without a
head expander. The window can be made taller.
These advantages have to be weighed against the
labor of chipping away the blindstop and shimming
and squaring the opening from “outside”. The dia-
grams show that the exterior “blindstop”, when
removed, clears the opening allowing a full height,
full width window to be securely installed
without the use of a head expander.
Outside-In Installation of
Box Frame Windows
Box Frame Installation of vinyl replacement windows
is based on "blindstop" techniques where the window 
is set into the opening from the inside of the house. 
Outside-In installation is accomplished from the 
outside the house and leaves the interior stops
intact. Paring away the exterior blindstop, removing
the parting stops and both sash provides a clear
opening to install the window from the outside 
without disturbing the interior and without having
to lift it over the stool to place it in the opening.
This is an advanced technique that is somewhat
more complicated than the traditional "blindstop"
method. But its advantage lies in giving satisfactory
results while probably being a more effective method
for installing all vinyl replacement windows. But, it is
important that the old window frame is adequately
integrated into the water management system of the
wall, or you should use frame out techniques.
Outside-in installation will require access to the
opening from outside the house, and though the 
window can be passed out of the opening from the
inside before it is set in place, it may be an advisable
and safer method to set the window in place from 
the outside. For openings above the ground floor, or 
for large or heavy windows, it is not recommended
that outside-in installations be done by one person.
Proper Flashing is Recommended
Window Fitters Guide to Window Installation 
48                ©2022 AWDI, LLC Do not reproduce without permission
If you leave the old frame
in, and install from the out-
side, it is best to “flash”
the opening.
Using liquid flashing on
the sill, a pan can be 
created that will allow 
any water intrusion to
drain to the outside.
Using adhesive-backed
applied flashing on the
jambs and header, make
sure the jamb overlaps the
sill, and the header flash-
ing overlaps the jambs.
SAMPLE MANUAL

View this content as a flipbook by clicking here.