Does EIFS Really Leak? Three Critical Non-EIFS Components That Make a Difference

20 • Interface March 2003
There has been much debate about Exterior Insulation and
Finish Systems (EIFS) and water intrusion problems, but a
large part of the problem really boils down to components
that are not part of the EIFS. Traditional EIFS cladding consists
of only four components that form the system. A complete system
includes the insulation board, base coat, reinforcing mesh,
and finish coat. Minor variations may include adhesive if the
base coat is not used for adhesive and the use of polyisocyanurate
foam insulation in place of the more common expanded
polystyrene (EPS) insulation. A water management (or drainable)
EIFS may also include mechanical fasteners and a moisture barrier.
This article pertains to a barrier-type EIFS that includes only
the four basic components.
Many EIFS applicators and contractors exclude some of the
most critical components that are not part of the EIFS cladding.
These additional components are essential, and the system is
likely doomed to fail without them. Critical non-EIFS components
that are commonly omitted but that have contributed significantly
to the failure of EIFS cladding (as well as many other
cladding types), include the kick-out flashing, sealant joints, and
sill flashing for windows and doors. These components are discussed
in detail below.
Kick-Out Flashing
The kick-out flashing is one of the few components related
to an EIFS installation that is typically the responsibility of the
roofing contractor. Kick-out flashing is required at all roof-towall
interfaces to divert water from the vertical sidewall away
from the EIFS. The two most common application areas for this
piece of flashing are the 90-degree intersection between a roof
and a wall and where a roof terminates into the side of a chimney.
The concept of the kick-out flashing is relatively simple in
that it has an angled leg to divert runoff from the roof rather
than allowing moisture to penetrate behind the EIFS and into
the wall assembly. Since these roof-to-wall interfaces occur well
above the ground, the consequence of unmitigated water intrusion
at these locations can be detrimental to the performance of
the cladding. Leaks can occur at the location of an omitted kickout
flashing and go unnoticed for a period of several years. It is
not uncommon for this condition to allow water intrusion that
can totally deteriorate the sheathing substrate and cause major
structural damage to the underlying framing. A detail of a typical
kick-out flashing is shown in Figure 1.
Sealant Joints
There are three accepted methods for installing sealant joints
in conjunction with EIFS cladding, but whatever the method, the
sealant joints are absolutely critical. The three acceptable sealant
methods include:
1) Backer rod and sealant (sometimes referred to as an engineered
sealant joint),
2) Seal tape, and
3) A fillet bead.
The sealant method selected is dependent upon the building
detail being considered. Sealants are required at the juncture of
dissimilar materials at all openings, penetrations, and terminations.
An opening would be considered a large void in the wall
for windows or doors, a penetration would be for such items as
pipes or cables, and a termination would be an area where the
EIFS butts into a concrete slab or masonry wall.
The sealant method shown in most typical details, and arguably
the most effective method, is a joint consisting of backer
rod and sealant. This method forms an expansion joint to
account for movement between dissimilar materials caused by
thermal movement and shrinkage. The backer rod is used as a
backup material to control the depth of the joint and create proper
sealant geometry. The sealant joint should be approximately
3/8 to 1 inch in width, have a width-to-depth ratio of 2 to 1, and
Figure 1: Metal Kickout Flashing resemble an hourglass cross section (see Figure 2).
March 2003 Interface • 21
It is important that the sealant is not applied to the EIFS finish
coat. An EIFS finish coat is not waterproof and is primarily
an aesthetic layer. Under certain conditions, if the sealant is
applied to the finish coat, an adhesive failure can occur as a
result of the tensile force of the sealant pulling the finish coat
away from the base coat. This condition typically takes several
years to occur as a result of long-term softening of the finish
coat in the presence of moisture. The matrix formed between the
base coat and reinforcing mesh is the waterproof layer of the
EIFS, and therefore, it is important that the sealant on the EIFS
side of the joint be applied only to the base coat. Absence of the
backer rod for this type of sealant joint can cause problems such
as joints that are too thick or too thin and joints that fail due to
adhesion to the substrate (three-point adhesion).
As a method to make the installation of sealant joints in EIFS
more economical, some EIFS manufacturers have allowed the use
of seal tape systems. A seal tape is simply a compressible foam
tape with a peel-and-stick surface which can be field installed.
This method is more economical than the
backer rod and sealant joint method and typically
goes in more quickly. It can be very effective
if properly utilized and installed. A typical
seal tape system is shown in Figure 3.
An alternative method of installing sealant
joints on an EIFS cladding is the use of a fillet
bead in conjunction with bond breaker tape.
This method can be used with new construction,
but is more commonly seen in retrofit
applications. For example, if EIFS was defectively
installed without proper sealant joints, a
fillet bead with bond breaker tape could be utilized
as a retrofit, provided that water intrusion
has not already compromised the system. The
sealant should still be applied to the base coat of the EIFS for the
reasons already noted, and the bond breaker tape is required to
create proper geometry of the sealant joint. As shown in Figure 4,
the bond breaker tape does create an approximate hourglass profile
of the sealant joint. Most bond breaker tapes have a peeland-
stick surface, but a thin bead of non-compatible sealant can
also be used as a bond breaker. For example, silicones and
polyurethane sealants will not stick to each other, and the use of
these two sealants together form an effective bond breaker and
sealant joint.
Sill Flashing Under Windows and Doors
Metal sill flashing is quite frequently omitted under windows,
even though it is shown in most typical details. Window manufacturers
have adopted a self-serving position that the entire window
is not designed and manufactured to be leakproof, and it
actually has what is classified as a wet zone and dry zone. The
dry zone of a window is typically from the face of the sheathing
inward and the wet zone is from the face of the sheathing outward.
This position may be suitable for those claddings that utilize
building paper, but for those claddings that do not utilize
building paper, water intrusion onto the face of the sheathing
can be quite harmful. For the record, there are also various wood
Figure 2: Sealant joint with backer rod
Figure 3: Seal tape.
Figure 4: Example of typical fillet beads termination.
22 • Interface March 2003
and composite claddings other than EIFS that do
not utilize or require building paper. EIFS cladding
is considered to be a barrier wall system and introducing
moisture into the wall assembly as a result of
window leakage can be very harmful. The solution
to this problem is the use of metal sill flashing (see
Figure 5 for typical window sill flashing).
The installation of a properly configured window
sill flashing is sometimes easier said than done. Many
residential windows and some commercial windows have nailing
fins and flanges under the sill. The sill flashing will discharge
moisture from the wet zone of the window beyond the face of
the EIFS. However, nailing fins (or flanges) will completely
obstruct the installation of the sill flashing. Some contractors
have gone so far as to remove the nailing fins from the bottom
of the window, but this procedure typically voids the window
manufacturer’s warranty and may create a building code violation.
If the window manufacturer is contacted, he may be able to
provide assistance, or the detail can simply be modified as shown
in Figure 6. This method is still effective but is somewhat more
expensive. It should also be noted that an effective sill flashing
under a window should have end dams and be configured in the
shape of what is sometimes called a sill pan. If the window is fastened
through the sill flashing, provisions should be made to
protect the fastener holes with sealant or a self-healing, peel and
stick flashing.
Conclusion
Omission of any of the three non-EIFS components
addressed by this article can be detrimental to the performance
of EIFS cladding. Although they are not part of traditional EIFS,
they are critical to system performance. These components are
also shown in EIFS manufacturers’ typical details. Proper installation
of these components will add to the cost of construction;
however, this cost should be considered negligible when compared
to the cost of repairs when these components are omitted
or installed improperly. For this reason, proper installation
of these components should be considered mandatory.
A barrier EIFS can be an attractive, functional, and dependable
cladding and will provide satisfactory performance if
properly installed. However, EIFS shares many similarities
with roofs, which are also barrier systems and will fail quickly
in the presence of long-term and excessive water intrusion.
We are now beginning to see more significant and costly consequences
of system failures. In addition to the obvious problems
associated with water intrusion, mold claims are
becoming serious concerns for contractors and insurance companies
alike. As most of us are aware, it only costs a little more
to pay attention to the details and do it right the first time. 
Alan Campbell is a principal
with the firm of Campbell,
Schneider and Associates, LLC. He
has over 21 years of experience as a
structural engineer and roof consultant
and is responsible for facility
condition inspections, failure analyses,
damage assessments, roof surveys,
and engineering investigations
of all types of structures. This effort
is related to structural failures and
deficiencies, faulty construction,
building code violations, and expert witness testimony. A large
percentage of Mr. Campbell’s practice focuses on the evaluation
of building envelope problems related to synthetic stucco,
conventional stucco, and roofing systems. Mr. Campbell’s
practice also includes the evaluation of structural defects and
failures attributable to catastrophic events such as hurricanes,
windstorms, and earthquakes. Mr. Campbell has provided
expert testimony related to wind versus flood, building code
violations, defective construction, coating failures, roofing
problems, and life safety issues.
ABOUT THE AUTHOR
ALAN CAMPBELL
Figure 6: Modified window sill flashing.
Figure 5: Window sill flashing.