Question:
I had weep screed on my stucco walls, but
recently had leaking and water coming through
the bottom of the wall. My contractor has now
sealed and painted the walls with elastomeric
paint so that they are solid at the bottom. Won’t this negate the
effect of the weep screed?
Is this an acceptable remedy, or am I likely
to have new/other problems now?
—via e-mail
Answer:
When I first saw this question, I immediately
knew that I was going to need to consult
with my stucco gurus to ensure that all the vari-ables
were covered. So as is my habit when in need of expert input in a hurry, I posted this question on AWCI’s NetForum (www.awci.org/netforum/awci/a) and sent
an SOS via e-mail in hopes of getting some good input.
This time I got more input than there’s room to print. Here are
some (edited) excerpts:
Mark Amacher of the Consultants Group writes: “Yes [there are
likely to be problems], if the weep screed was sealed. I would
also ask what type of elastomeric was used.”
Morley Margolis of Honsador Lumber writes: “Generally water
doesn’t go through a system. Water goes around a system.
Therefore you must first check for proper flashings at the top
of the wall and at the roof. Caulking around windows, doors
and other penetrations must also be checked. The windows
themselves must be checked to be sure that they are not leaking.
Weep screed is installed primarily as a starting ledge for
the stucco. It has drainage holes in it to let incidental moisture
out. Elastomeric coatings are put on to cover small cracking in
the finish. Any cracks over 1/32 of an inch should be filled
before doing anything else to the wall. However, nothing will
work until you find out where the water is coming from.”
Darin Coats of the Western Wall and Ceiling Contractor’s Association’s
Technical Service Information Bureau writes: “The
purpose of the foundation weep screed is to counter flash the
transition at the sill plate of the wall to the slab or curb it sits
on. Additionally, the weep screed provides a path by which
water can flow out of the plaster wall, The location of the weep
screed is very important; the 3 1/2-inch vertical flange leg must
bridge the connection of the slab and sill plate. Per the Uniform
Building Code, this screed will be located a minimum of 4 inches above dirt or a minimum of 2 inches above paved areas. The
dimension is measured from the leading edge of the screed,
where the stucco stops. Install the screed first, then the building paper being sure to cover the 3 1/2-inch vertical flange leg.”
Frank Guidera of Performance Exteriors writes: “You are correct
that by sealing the holes up, the water cannot weep. I would like
to know where the water is coming in. It sounds like an improper installation of the barrier, which means that it probably doesn’t overlap the flange of the weep screed. . . . As far as the elastomeric coating, I would question the reason for that all together. If you have water leaking behind the system, paint won’t fix
it.”
Walt Pruter, president of the International Institute of Lath and
Plaster, writes: “Prior to including requirements for Foundation
Weep Screeds in the 1975 Building Code, many buildings built
on slabs-on-grade and clad with portland cement plastered exterior
walls experienced water intrusion problems at the mudsill. . . .
The foundation weep screed also prevents plaster from being
directly applied to the footings or foundations where it could create
a dam that directs water in the plaster back under the weather
barrier and into the building. In an appropriate thickness, elastomeric
coatings help bar external moisture from penetrating
through the plaster membrane but the elastomeric also retards
the escape of moisture that entered the construction by percolating
up through slabs or by circumventing flashing and sealants
where plaster abuts other materials or has open penetrations.
About the Author
Lee G. Jones is AWCI’s director of technical services. Send your
questions to him in care of this magazine.
