DESIGN/RAIN PENETRATION
Exterior Insulation Finish Systems
EIFS systems employ the face-seal approach to the control of both air leakage and rain penetration.
Water-tightness is very important in EIFS systems to prevent the degradation of system
components, particularly the exterior gypsum sheathing in the case of a steel stud backup system.
The finish coat, as see in Figure 3.4.13, serves as both the air and water seal. Leakage can occur
at panel joints, locations where the finish has delaminated and at voids in the finish coat when they
are exposed to moisture for extended periods of time. The latter problem of exposure can occur at
joints that are not designed to drain well and at other facade articulations. It is very important in this
system that roof edges, window sills and other articulations are designed to shed water away from
the facade.
Finish
coat
-
Substrate
Reinforcing mesh
Base coat
Joint sealant
Rigid insulation
Figure 3.4.13 Exterior Insulation Finish System (Williams)
PAGE 3.4-13
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