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Knowing the range of interactions amongst components in the exterior building
envelope is not easy. Nevertheless, it is the specifying professional’s responsibility
to research and determine what conﬁgurations will properly function.
kitchen—moving one’s hand into a 200-C (400-F)
oven, without touching any surfaces, is quite different
from plunging a hand into boiling water.
Good thermal insulators—sprayed polyurethane
foam (SPF) and rigid boardstock, for example—
have a lot of air molecules in proportion to other
dense molecules; further, the former is effectively
positioned between the latter to make this separation.
A good example of this is the cardboard sleeve that
slides around a paper cup of hot coffee, allowing
someone to comfortably hold a steaming beverage.
The clear takeaway for the building industry is
to have an impact on a temperature relationship
of a building from inside to outside (or outside to
inside), one must insulate the exterior building
envelope—the walls, ﬂoors, and roof (Figure 1).
Another critical requirement is keeping the
insulation material dry. Wet insulation is not an
insulator, but rather a conductor. Different types
of insulation materials absorb moisture at different
rates. In many instances, an exterior building
envelope with no insulation is preferable to one with
wet insulation. Of course, the problems of wet
insulation in a wall do not end with just poor
insulation values. They also include mold, pest
infiltration, and building material degradation.
As shown in Figure 2 (page 70), there are many
causes of wet insulation in the exterior building
envelope. Examples include:
• uncovered insulation stored in an exposed
location on a jobsite can be installed in a
• liquid water can egress into the exterior
building envelope during and after the
• moisture (in the form of water vapor) can
enter the building envelope from the exterior
• liquid water can leak from faulty plumbing; and
• poorly insulated plumbing or HVAC ductwork
can condense and drip water.
Moisture problems with EIFS are often in areas
where the system abuts other materials such
as wood trim, at the top wall, at roof flashing,
Controlling the temperature relationship of a building from inside to outside
(or outside to inside) means insulating the exterior building envelope.
around wall openings, and where other items
penetrate the cladding’s surface. EIFS can also
develop penetrations over time—foundations
move, walls crack, storms can blow debris into
façades, etc. There can often be installation
issues. Even though manufacturers of EIFS
products have recommended best practices and
procedures, onsite labor does not always follow
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