Exterior Insulation and Finish System
(EIFS)
Note - This information is
provided as a courtesy to our clients.
AccuSpec Inspections does NOT
perform EIFS inspections or EIFS applications.
We recommend that all EIFS systems be tested annually by a qualified
contractor. One contractor in our area is Engineering Testing Corp at
757-486-5552. Refer to our
Contractor List.
Exterior Insulation and Finish Systems
(EIFS), commonly known as synthetic stucco, is an exterior cladding
system composed of an adhesively or mechanically fastened foam
insulation board, reinforcing mesh, a base coat, and an outer finish
coat. EIFS is available in various colors and external textures designed
to look like traditional stucco. Its exterior appearance looks almost
identical to conventional stucco, although conventional stucco is
comprised of multiple layers of cement over a wire mesh.
Home purchasers are attracted to EIFS
because of its majestic look. The exterior cladding makes normal homes
stand out and delivers fantastic curb appeal.
Architects and builders are attracted to
EIFS because the expanded polystyrene (EPS) insulation used in this
product is easily shaped and sculpted. The EPS insulation can be used
for making decorative bands, quoins, and other adornments on homes. In
addition, EIFS is a competitively priced alternative to conventional
stucco or brick siding.
EIFS is also popular because it acts as a
great insulator. Besides offering design flexibility, EIFS insulation
boards can cover a building’s entire exterior wall space, in essence
eliminating any thermal breaks in the insulation barrier. This can
reduce energy consumption, reduce air infiltration and increases
interior comfort..
Dryvit Systems, Inc. introduced EIFS into
the United States in 1969. With the onset of the energy crisis during
the early 1970s, EIFS became popular among energy-conscientious
architects and builders. During the energy crisis, many U.S. and
European manufacturers entered the EIFS market place.
EIFS manufacturers began marketing EIFS to
the residential market in conjunction with the increase in housing
starts that began in the mid-1980s. Touting energy efficiency, design
flexibility and curb appeal, EIFS manufacturers successfully marketed
their product line to high-end builders. During the 1980s, EIFS became a
cladding of choice for many higher-priced residential homes.
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EIFS System Problems
The problem with barrier-type EIFS cladding
is that the systems rely entirely on their outside surface to prevent
water penetration and moisture intrusion. Barrier EIFS have no internal
drainage provision, and therefore require excellent design and
workmanship to produce a weather-tight and long-lasting system.
Throughout the United States, a significant percentage of homes clad
with barrier-type EIFS are experiencing problems with water penetration
and moisture intrusion, primarily around windows, doors, and
roof-to-sidewall intersections where kick-out flashing is necessary. The
retention of moisture in these systems for an extended period of time
invariably leads to damage that frequently goes undetected for an
extended period of time. In many homes clad with barrier EIFS, water
that enters behind cladding does not evaporate, or “escape,” quickly
enough to allow structural members to dry out. The moisture content and
temperature inside the wall cavities of these homes often promote rapid
growth of wood destroying fungus, leading to deterioration or rot of the
sheathing/substrate. Depending on the size of the home, EIFS repairs can
range from tens of thousands to over one hundred thousand dollars.
In contrast to residential construction,
most high-rise condominiums, office buildings, and stores are made of
concrete and steel. While problems with barrier-type EIFS have also been
widely reported on these structures, such problems have generally taken
a longer period of time to manifest then is the case with wood-framed
residential construction.
The problems associated with barrier-type
EIFS in residential construction first came to light in Wilmington,
North Carolina, where inspectors began acting upon an
unusually high
number of homeowner complaints concerning water damage to their EIFS
homes. However, building inspectors throughout the country now point out
that similar problems are being discovered in a number of states,
including Alabama, Colorado, Florida, Georgia, Illinois, Indiana,
Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Mississippi,
Missouri, New Jersey, New York, North Dakota, Ohio, Oregon,
Pennsylvania, South Carolina, Tennessee, Texas, Utah, Virginia, and
Washington. Problems have also been discovered throughout Canada,
notably Vancouver, British Columbia and Saskatchewan.
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The EIFS industry, as represented by the
EIFS Industry Members Association (EIMA), initially characterized the
problems with barrier EIFS in Wilmington as “unique” and an “isolated
problem.” Assumptions were made that, due to a unique set of
circumstances, moisture was able to find its way into homes in coastal
regions that featured high levels of humidity or sustained periods of
rainfall. When reports of similar problems surfaced in other areas of
North Carolina as well as other states, the North Carolina Office of the
Attorney General directed builders, developers and real estate agents to
provide a disclosure form to prospective purchasers of EIFS-clad homes
before any serious negotiations begin. The North Carolina Association of
Realtors EIFS Disclosure Statement states the following:
The house you are considering purchasing
is clad with a product known as exterior insulation and finishing
system (“EIFS, also referred as “synthetic stucco”). You should be
aware that tests performed on a number of EIFS-clad homes in certain
parts of North Carolina have revealed moisture-related problems. In
Wilmington, 90 percent of the homes tested by local architects and
building inspectors exhibited problems. Testing has shown that
moisture entering the wall cavities may become trapped behind the
EIFS exterior. In some cases, the trapped moisture has caused
substantial damage, including rot, to underlying wood sheathing and
framing members. In other cases, little or no damage has been
observed.
Legal responsibility for correction of
the observed problems has yet to be determined. Several class action
lawsuits have been filed by homeowners against certain EIFS
manufacturers. In addition, several individual lawsuits against
builders, manufacturers and trades men known as EIFS applicators
have been filed in the Wilmington area. These lawsuits are currently
pending.
On March 12, 1996, the North Carolina
Building Code Council adopted stringent guidelines for the
application of EIFS to new residential structures and for any
repairs of existing EIFS-clad houses with moisture damage problems.
The Council is expected to tighten these requirements further by
mandating that drainage systems be installed in the exterior walls
of all EIFS-clad homes contracted in the future.
Before deciding to buy, you may want to
have the house tested by a qualified moisture intrusion expert using
EIFS testing guidelines available from the North Carolina Department
of Insurance’s Engineering Division (919) 733-3901.
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EIFS Problem Causes
Deviation from
installation guidelines
EIFS application requires strict
observance of manufacturer recommended specifications and guidelines and
involves meticulous workmanship and attention to detail. When improperly
applied, the EIFS cladding does not perform its intended function and
allows water to infiltrate behind the cladding, where it becomes
trapped.
EIFS details are procedures outlined by the
EIFS manufacturer that provide guidance to the architect, builder and
applicator as to the proper installation of the product. All EIFS
manufacturers have details and procedures that builders and applicators
are expected to follow. Installation details are typically very similar
among EIFS products and EIFS manufacturers, but there are differences.
EIFS must be purchased from an EIFS
distributor. The manufacturer or distributor trains applicators and
issues certificates stating that the applicator has been properly
trained. It is the responsibility of the distributor to ensure that EIFS
is sold only to those certified applicators.
Foam insulation placed below grade
Prior to recent building code
changes, the expanded polystyrene (EPS) foam board insulation used in
EIFS was placed on the wall below grade. It was discovered that foam in
contact with the ground causes conditions conducive to termite
infestations. Often times, the first indication that an infestation
problem exists is a swarm of termites. This swarm occurs either inside
the structure or close to the outside of the home. Other indications of
infestation problems are mud tubes or galleries of mud on a foundation
wall. With EIFS-clad homes, the visible evidence of infestation is
blocked from view by the exterior siding. In fact, the exterior siding
typically looks pristine and shows no signs of any problems. Behind the
EIFS cladding, the termites tunnel galleries in the wet foam and
establish themselves inside the home. In those instances where the foam
retains moisture and does not dry out, termites are able to break their
contact with the ground and exploit the moisture source above ground.
Another problem with placing the foam below
grade is the ability of water vapor to migrate upwards through the EPS
foam. When the temperature rises at the transition from masonry to wood,
the water vapor condenses and causes water to settle on the sill plates
and exterior band joist. If this water does not evaporate quickly, wood
rot can set in and decay the structural members of the home.
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Missing secondary weather barrier and
inability to drain
Most wood-framed residential
homes require a secondary weather barrier to be placed over the
sheathing before the exterior cladding is installed. This barrier
protects the home from incidental water intrusion and allows moisture to
exit the home by traveling on top of the barrier, keeping the sheathing
and structural members relatively dry. Eliminating a barrier and
rendering a substrate unprotected invites trouble, no matter what type
of exterior cladding is used.
Due to the design of the EIFS, a majority of
EIFS clad homes do not have a secondary weather barrier placed over the
exterior sheathing. A large number of EIFS applications use an adhesive
to fasten the two-foot by four-foot insulation boards to the sheathing.
If an adhesive is used to hold the insulation boards to the sheathing,
then a secondary weather barrier cannot be used. Any water that
infiltrates the system will become trapped between the EIFS and the
sheathing.
It is estimated that 95 percent of homes
clad with EIFS in the United States are barrier-type. Most barrier EIFS
projects are adhesively applied because it is less time consuming to
install. Adhesively applied EIFS prohibits a vapor barrier from being
installed. It also prevents many self-flashing windows from being
installed properly since the sill flashing must be cut off to
accommodate the adhesively attached foam board.
Divided responsibilities
An EIFS applicator is responsible for the application process-attaching
the foam insulation to the substrate, applying the fiberglass mesh,
embedding the fiberglass mesh with base coat and applying a finish coat.
Many details outlined by manufacturers require the services of other
tradesmen. A typical EIFS applicator does not install backer rods and
sealant, but should install the EIFS so that it is possible to install
these critical components. The builder is responsible for subcontracting
the backer rod and sealant components. Flashing around windows, doors,
decks, chimneys and roofs is the responsibility of the builder and his
roofer. The applicator should recognize improper flashing and not
continue the application process until the problem is corrected.
According to the National Association of Home Builders Research Center,
“This divided responsibility combined with the need for special
construction details are alleged as the causes of premature failure” of
EIFS.
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Other contributing factors
Many homes have been constructed
with an interior poly-vapor-barrier. A plastic sheet covers the interior
wall studs and insulation behind the drywall. This barrier reduces the
wall’s ability to dry. According to the NAHB Research Center, “The
poly-vapor-barrier increases drying time in a wall with EIFS cladding by
approximately eight-fold.”
Leaking windows, which allow moisture to
enter behind the cladding, have also been documented as a problem. The
quality of windows installed with the EIFS is directly related to the
amount of water that will infiltrate. For example, wood windows perform
poorly, while welded seam vinyl windows perform substantially better
than other window types.
Pressure differentials
Barrier EIFS is a face-sealed system. The
system relies on a water and airtight seal over the entire wall system.
When this is achieved, an air cavity is created between the exterior
sheathing behind the EIFS and the interior of the home. Positive air
pressure changes caused by wind on the exterior of the home create a
negative pressure in the wall cavity. Any breach in the barrier EIFS
system will force air through that opening and into the wall cavity.
When rain is introduced in this scenario, water, not air, is forced
through any breach in the barrier EIFS. Many researchers indicate that
the difference in pressure differentials is responsible for the majority
of the water intrusions in face-sealed systems.
Other wall claddings such as brick, lap
siding, shingles and traditional stucco allow air to infiltrate, thus
rendering the positive force applied to the building balanced.
Note - This information is
provided as a courtesy to our clients.
AccuSpec Inspections does NOT
perform EIFS inspections or EIFS applications.
We recommend that all EIFS systems be tested annually by a qualified
contractor. One contractor in our area is Engineering Testing Corp at
757-486-5552. Refer to our
Contractor List.
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