Installing Patio
or Entry Doors
Installing Patio Doors or Entry Doors is similar to installing
windows. In New Construction, preparation of the opening
with proper flashing is key to preventing leaks and preserv-
ing energy performance. Installing doors in replacement
applications is as complicated as replacing windows for the
simple reason the removal of the old door is as destructive
to the water management system as with any window tear-
out.
There are three considerations with doors that require
effort in the preparation to be sure that the resulting 
installation (new construction or replacement) allows the
door to operate properly and be weather tight:
1. Level Sill. The biggest single problem source 
for poorly operating doors - either rolling or hinged - is an
unlevel sill. As the artwork shows, a crown, a bow or a 
sill with one side higher than the other, will not allow the
interlocks and weather stripping to engage as designed. 
If you start with a level sill, good results from the installa-
tion are all but assured. If you don’t, then bad results will
surely follow.
2. weather resistive Sill. In new construction,
establishing a level and properly draining sill that expels
water and moisture that makes its way behind the weather
Window Fitters Guide to Window Installation 
107               ©2022 AWDI, LLC Do not reproduce without permission
CROWN IN SILL
BOW IN SILL
UNLEVEL SILL
SAMPLE MANUAL

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