Know the methods of protocol when signs of water and moisture intrusion occur.
I doubt anyone would disagree that water
leaks have been the primary driving force behind defect litigation. Everyone
seems to go to extreme lengths to prevent them and protect themselves. All this
has also led to an explosion of a cottage industry for investigation and the
testing for leaks in walls and windows. When water-leakage or moisture problems
are in question, there is an established protocol to follow, which in turn
reference certain proper tests for water leakage.
With respect to known leaks, an investigation including specification, plan
review, and interviews should be completed prior to window water testing
procedures. And while the protocol calls for agreement on procedures, many
expert opinions are not always agreed upon before, during and after the water
testing is initiated. A majority of the time “maintenance” has been an issue
with respect to existing sealant separation from aging of the building or the
absence of a sealant. It just makes perfect sense to seal these locations prior
to performing ASTM water testing protocol.
the event of eventual litigation, it is important to follow an established and
recognized protocol. Some steps can be eliminated or enhanced; test pressures
can be increased, when all parties agree. Not surprisingly, the ASTM protocol
has this language in the standard for testing. In facilitating whether or not a
window has ever leaked, the following information can be helpful in sequence to
gather clear and concise documentation during the water testing procedures. For
many stucco contractors, this world is confusing and seemingly unfair, but when
done properly, can be informative and even helpful. When water testing is
deemed necessary, it is always recommended to use the proper or realistic
design pressure for the ASTM test by an AAMA accredited laboratory or a
LINES OF DEFENSE
Test-induced window leaks are leaks in which there is no history of
pre-staining and no sign of leakage existed prior to window testing.
Window flashing and water-resistive barriers, the second line of defense, are
installed per the building code standards at the time of construction. A
test-induced leak can occur when water that has been injected into the gaps
between the window frame and the boarding stucco assembly collects in front of
the water-resistive barriers and dams up at the window flashing sill jamb
corner intersection. When more than incidental and under high negative
pressure, it is possible to travel over the window flashing or down the face of
framing members onto the sole plate.
water reaches the back plane of the scratch coat and is allowed to become
trapped between the scratch coat and the water-resistive barrier, under the
right circumstances leaks can occur through lathing fasteners.
The most common locations for water entry are terminations and/or penetrations
in the cement membrane of different materials, such as aluminum and vinyl
windows, wood corbels, electrical components, imbedded wood trims, trellis
ledgers, fascia board returns, utility panels, etc., that break up the
monolithic stucco panel. Without a sealant, these areas can potentially cause
test-induced leaks, where no signs of leakage existed prior to water testing.
When evidence of previous water stains are present in the stud bay cavities, a
competent forensic expert will record the stain history by outlining the
perimeter of these locations with a permanent marker before any water testing
begins. Many forensic experts argue that previous stains on framing members may
have been “construction stains” while the building was constructed and exposed
to the weather elements prior to being clad. This is why it is recommended to
document all stain history prior to water testing. The spray rack is a useful
tool when used properly by the credible applicator. Water testing, done under
design pressures per the “Components and Claddings” section of the code, can
verify if the water stains are “construction stains,” active leaks or test
within the outlined stain line are likely an active leak-leaks beyond the
outlined stain are likely test induced leaks and would require a reconfirmation
that proper protocol was followed and realistic design pressures were used. No
leak would indicate that the stain was indeed a construction stain.
THOSE PESKY CONTROL JOINTS
Control joints in Portland cement stucco are intended to primarily act as
artificial planes of weakness to theoretically allow dissipation of stress
energy generated by building components at the control joint, rather than find
relief in the form of a crack or break in the stucco. Control joints are
components of the lath and plaster assembly and not a component of the structure.
Frame buildings must have a water-resistive barrier over all exposed surfaces.
This WRB is recommended to be vapor permeable and should be installed in a
“shingle-lap fashion.” (Shingle lap means that upper layers always over lap the
lower layers.) This installation practice allows incidental moisture to travel
downward and ultimately escape at a weep point. Some incidental moisture is
absorbed into the cement scratch coat and will escape by solar energy. Solar
energy cannot account for significant volumes of water, and if the moisture is
allowed to become trapped, problems may arise.
The control joint is a single piece trim accessory intended for limited
movement. A control joint has no intended weep provision or flashing flange;
the water-resistive barrier must be continuous behind the control joint. The
lath may be discontinuous but the WRB must be intact and continuous. This often
gives the plasterer a sense of security that water that finds it way through
intersection and/or terminations of the control joints will not be a problem.
But sometimes it is a problem and will confuse the contractor. The issue is the
volume of water entry at these gaps vs. the volume of water exit at the weep
point. If the water that enters is at a greater rate than the water can exit,
water can dam up and seek other avenues of exit. In extreme cases, the water
can even backup and overwhelm a shingle-lap. It is important to “manage” water
entry and maximize exit points to keep the assembly in balance.
contractors think of the “crack” mitigation function of the control joint and
too often neglect the “water” entry prevention issue. I would recommend think
water entry first and foremost to prevent problems. Setting control joint
intersections and terminations in a daub of sealant is good practice on walls
that will be exposed to rain. The cement plaster then encases the sealant,
protecting it for years to come from ultra-violet rays. If the installation of
plaster is complete and the lather failed to back seal the terminations,
intersections and gaps, they can be sealed later. To keep these after plaster
sealant applications functioning, they should be inspected annually and
repaired as needed to keep water entry to only incidental moisture and the
assembly in proper water management balance.
Envelope consultants often overlook the importance of control joint termination
and intersections and focus on the cement membrane. Most are unaware that a
properly mixed and applied cement membrane is extremely water-resistant and
will not allow liquid water to pass through. Several independent labs and
plaster bureaus have verified this fact. Focusing on the proper attachment of
control joints and one-piece reveals will pay off with a leak free wall