Brick Design: What the Third Pig Knew

8 • Interface June 2002
By Cathy Murphy
As the story of the three little pigs illustrates, masonry
structures can be quite durable. But in order for this to
be the case, the engineer and the mason have to do their
jobs properly. Regardless of the requirements established
by the engineer, the owner will experience problems if
the mason doesn’t follow them. Issues arise when the
structural engineer’s design isn’t as constructible as it
could be or when certain aspects of the design are overlooked
or ignored.
This gap between what is designed and what is actually
constructed has created a stigma about masonry’s
quality. Jerry Painter, president of Painter Masonry in
Gainesville, Fla., said that when structural engineers find
flaws in masonry construction, they naturally tend to
design less masonry. In addition, he said that unless
engineers are working on large projects with sophisticated
owners or state governments, they tend not to
inspect construction work at all. In this situation,
some engineers compensate by over-designing
masonry projects.
F i g u re 1: This otherwise attractive building had to be evacuated because of hazardous spore s
inside caused by inadequate or missing flashing of the masonry veneer. Photo courtesy Norm
L. Cooper, P. E .
After the wolf blew down the straw house and the stick house (and, by some accounts, filled up on fresh
pork), he came to the third pig’s house — the one made of brick. The wolf knocked on the door and said,
“Little pig, little pig, let me come in,” and the pig answered, “Not by the hair on my chinny chin chin.” So
the wolf huffed, and he puffed, and he puffed, and he huffed, but he couldn’t blow the brick house down.
June 2002 Interface • 9
Both of these situations create additional
problems. When engineers overdesign,
costs increase. And when they
choose other materials because they
aren’t confident in the mason’s abilities,
they’re missing out on the benefits of a
quality product. When designed and constructed
appropriately, masonry is versatile,
durable, aesthetically-pleasing,
environmentally-friendly, and resistant to
fires and earthquakes.
Of course, problems can happen with
any type of building material — not just
masonry. According to Gary C. Hart,
Ph.D., P.E., a principal and division head
with New York-based Weidlinger
Associates Inc. and former president of
the Masonry Society, “Masonry gets a
[reputation] as having worse quality control
than concrete or steel, but I’m not
really sure that’s true. I think by the
nature of masonry, maybe it shows when
the quality of construction is bad a little
more than steel and concrete because you
have a lot of water leakage problems that
tend to show up. But if you’re talking about placement of steel or
welding, I’m not sure there’s a big, big jump in quality by going
to concrete or steel. The problem is more widespread than people
would like to believe. They like to pick on masonry, but I
think it’s just a fundamental problem with attitude and accountability
of contractors.”
THE ISSUES
Before we can solve the problems related to masonry construction,
we must know the origins of the problems. Structural
engineers alone can’t solve every issue that affects their projects.
Some are industry-wide issues that would require a great deal of
time and input to change. Others are specific problems that
engineers can identify on jobsites and have contractors fix or
solve in other ways.
For example, Painter said that one of the most common
problems he sees occurs when electrical, plumbing, and HVAC
components are designed to go through a structural wall. “When
the wall is heavily reinforced and grouted, and all of a sudden we
start getting all these components that have to go through or be
in our wall, they conflict with our rebar and grout,” he said.
Norm Cooper, P.E., chief engineer with Realty Engineering,
Inc., a nationwide firm based in Canyon Lake, Texas, said that he
has served as an expert witness in over 200 cases in several states
involving inadequate masonry. Cooper identified eight problematic
areas in masonry construction, including flashing, cracking,
ties, arches, alignments, mortar, weep holes, and defective brick.
Following is an explanation of each area.
Flashing
Problems with flashing are the most serious, according to
Cooper, because they lead to water penetration, which can cause
rot, hazardous spores, and mold. He estimates that about 15 percent
of the masonry buildings he’s inspected had problems with
flashing. In fact, some occupants have been forced to evacuate
after Cooper and his staff detected these anomalies, which are
generally caused by improper construction. Flashing errors can
be extremely detrimental to the health of a building’s occupants.
W.T. “Dusty” Yaxley, P.E., a forensic and consulting engineer in
Tampa, Fla., said that in one case, he detected a dangerous type
of mold in the house of a family of three. Because of the mold,
the young daughter developed serious respiratory problems and
the father, who was only in his 30s, developed irreversible brain
damage that was so severe that he was unable to work.
Besides health-related problems, leaking from improper
installation of flashing can also lead to structural deterioration.
Painter recently encountered this situation on a retrofit project
originally constructed in the 1950s. He said his workers took
some limestone coping off the top to investigate behind the
panel and found many rusted anchors, including a 3⁄16-inch galvanized
steel strap that was “practically rusted away.”
Cooper said one reason for the improper flashing installation
is that building codes are quite brief and aren’t specific enough
about how to install the flashing. Although he said the Brick
Industry Association (BIA), based in Reston, Va., provides more
specific guidelines in its technical documents (available at
www.bia.org), these documents are not always consulted.
Several common scenarios can create problems during or
after installation of flashing. Gregg Borchelt, P.E., vice president
for BIA, named all of the following:
• Flashing not properly installed from a height standpoint
— without a sufficient rise from the brick through the
airspace to the flashing attachments to the backing.
• Improper sealing of flashing elements.
• Flashing damaged by subsequent construction such as
welding taking place above the flashing and creating
sparks that burn holes in the flashing.
F i g u re 2: Missing and inadequate flashing behind brick siding caused leaks into a house, which caused haza
rdous spores. Photo courtesy Norm L. Cooper, P. E .
Cracking
Cooper noted that poor drainage creates
many cracking problems, particularly
on jobsites with clay soils. High and variable
clay moisture causes loss of bearing
capacity and shrinking or swelling, moving
the foundation, usually unevenly.
Although building codes specify the
drainage slopes that should be used,
architects, engineers, and contractors
alike often ignore them. In fact, Cooper
said it is the most repeated problem
found by his firm’s many thousands of
inspections. He estimated that drainage
slopes aren’t graded properly over 50 percent
of the time.
Borchelt states that cracking problems
tend to show up with time, especially
with concrete frames that undergo
creep and shrinkage and with moistur e
expansion of brick veneer. He said these
are typically just aesthetic problems, but
if they’re left unattended, very high compressive
stresses in the brick wythe could
develop, which increases the potential
for that segment of the masonry to come
off the wall.
According to Borchelt, if the vertical
support isn’t designed and detailed correctly,
there is cracking of one of two
types. “If you have a horizontal spandrel
section of masonry separated by horizontal
bands of windows, [and] the spandrel
beam isn’t designed [for] the weight and
June 2002 Interface • 11
F i g u res 3-5: Interior water damage and org a n i s m s
caused by inadequate flashing. Photos court e s y
N o rm L. Cooper, P. E .
stiffness of the brick veneer, you can get some vertical or sometimes
diagonal step cracking in the brick wythe,” he said. “That
tends to happen more in steel framed structures, where people
just don’t take into consideration the fact that masonry tends to
act as a beam of its own. If there are not appropriate deflection
limits on the supporting structure, you can get the masonry acting
as the beam, and if it doesn’t have sufficient strength, you get
the vertical cracking.”
“The second circumstance,” he continued, “would be when
you have a continuous vertical section of brickwork with a shelf
angle supporting that brickwork at each floor or at alternate
floors. In that circumstance, if the angle supporting that brickwork
isn’t detailed properly to account for both differential
movement between the building frame and the brick veneer or
deflection of steel angle itself, you get some spalling and sometimes
vertical cracking at that shelf angle. That’s probably more
common than the first circumstance.”
Of course, cracking can also occur because of construction
problems. Borchelt said that locating vertical expansion joints
correctly is important for crack control.
“It’s not uncommon to see some misplacement of the vertical
or horizontal steel or substandard vibration of the grout that’s in
the cell with the steel,” said Hart. “Sometimes it causes cracking,
which raises the flag for the owner to call in an attorney or an
engineer, and then they start arguing about whose fault it is. The
culprit, in my experience, is usually the contractor, who just
wants to build faster than he should, so he puts too much water
in or doesn’t worry about how much water, or doesn’t vibrate it.”
Yaxley explained a common problem that can cause cracking:
“You find everything (in the cells to receive grout), from coffee
cups to plates to plugs and all kinds of things. What normally
happens is they have a little tin thing they call an ashtray that
they put in the top of the block (to stop grout flow.) Then they
leave that out where they want the grout poured down the hole
into the wall. If there’s not a rod sticking out there when the
mason gets to the top, then he doesn’t put the little ash tray in,
which means that it doesn’t get filled with grout; even though
the reinforcing bar may be stuck out of the foundation, it’s just
not there at the top. So when the engineer goes out to check for
filled cells, and he takes a hammer and thumps along the edge…
if he knocks a hole, often… he’ll find the rebar at the bottom,
but it doesn’t continue on to tie in with the tie beam, which is
not an uncommon problem.”
Ties
Although metal ties are required between brick veneer and
the structure of a building, it’s difficult to detect whether they’re
adequately placed after a project is completed. This problem can
be serious. “Sometimes, ties are missing or inadequate, and you
start having movement of the brick siding, which can be hazardous,”
said Cooper.
Borchelt said that when he observes buildings after earthquakes
and tornadoes, it’s “relatively common” to find that contractors
have either completely omitted veneer ties or haven’t
placed them properly. They should be embedded in mortar
joints and able to transfer wind loads from the veneer to the
backing system. He’s not sure why contractors completely omit
the ties but said that when they aren’t embedded properly, it
could be because there’s too great a dimensional tolerance variation
between the backing wythe and the backing system that’s
attached to the structural frame versus the dimensional tolerance
of the brick veneer, which generally has to be tighter in plumb
and alignment than the structure in back of it. If the tie doesn’t
fit properly, the contractor might change the shape of the wire
to fit without understanding the consequences.
Arches
Cooper often sees arches over openings rather than headers
or lintles. “When you build a brick arch,” he said, “if it’s done
right, the brick itself will hold up [the arch] without a steel
header because it’s got a proper height versus the width of the
arch. But we find maybe 20 percent are not adequately built,
[and] sometimes not adequately designed. They can crack and
can fail and be hazardous.”
The arches fail for different reasons. For example, Borchelt
said they may miss sufficient abutment on the side to prevent
spreading, or the pier supporting a column might be too high
to rotate.
Alignments
Although it’s usually only an aesthetic problem, Cooper said
he’s observed many projects where requirements for alignment of
horizontal and vertical construction are not met.
12 • Interface June 2002
June 2002 Interface • 13
Mortar
Cooper said he’s seen problems with mortar in about five percent
of the construction he’s inspected. Sometimes the mortar
has inadequate strength. “If you can scrape it out with a screwdriver,
it’s not going to meet strength requirements,” he said. “In
other situations, if the brick is very absorbent, it sucks the moisture
out of the mortar, which doesn’t allow it to adhere to the
brick and creates cracking.”
Yaxley said, “You’d be hard-pressed to go out on a job and
find appropriate quality control for mortars. It doesn’t matter
what is specified.” To compound the problem,
it’s impossible to verify the specific
mortar strength that was used on a given
project after it’s hardened.
Weep holes
Cooper notes the weep holes are often
missing or blocked, which can create
some of the same types of problems
caused by inadequate flashing. During
construction, mortar droppings in the airspace
behind the veneer can plug or clog
weep holes. Borchelt said that these droppings
can also provide bridging so that
water can come in contact with the
sheathing and get into the building.
Sometimes problems occur after construction
as well. Yaxley said owners and
even some contractors don’t understand
why weep holes are used and that masonry
is designed to be water resistant, not
waterproof. In some cases, buildings may
be adequately constructed, but when the
owner sees evidence of moisture toward
the bottom of a wall and notices the weep
holes, he or she calls a renovation contractor,
who plugs the holes without realizing
the consequences.
Defective brick
Although defective brick is much more
rare than any of the other problems mentioned
above, Cooper said he has
observed projects where the brick has simply
been inadequate. In these situations,
the outer portion of the brick flakes out
of the wall, or the bricks themselves
crack internally.
WHY THE ISSUES EXIST
One reason some of these problems
occur is the lack of masonry education in
many college engineering programs.
“Sometimes I think there are engineers
who may not understand masonry,” said
Painter. “Masonry’s not something that’s
taught in a big way in engineering and architecture schools.” In
fact, he said that only one masonry class is taught for one semester
per year at the University of Florida. In other schools, no
masonry classes are taught, let alone required.
Of course, problems exist on the construction side as well.
According to Painter, who’s been working in the business for 33
years, “There is a shortage, and we as an industry have really
failed over the last couple of generations in properly training the
ongoing workforce.” To worsen the situation, Painter said that
the mason’s job has gotten much more complicated over the past
F i g u re 6: Blocked (or missing) weepholes cause water accumulation, rot, and hazardous spores. Photo court e s y
N o rm L. Cooper, P. E .
F i g u re 7: Arch with inadequate height cracked and subject to hazardous failure. Photo courtesy Norm L.
C o o p e r, P. E .
two decades. Masonry walls are being used as shear walls more
often, and there’s more to learn about rebar, grout, anchoring, et
cetera. “Twenty years ago, we never saw a number 8 in a masonry
wall,” he said.
Yet Painter said that many masons are resistant to training.
“Masons generally just want to lay block… You try to explain to
them that the rebar needs to be where the rebar needs to be —
it needs to be at this space or centered where it’s designed, the
two bars need to be bundled or they need to be separate —
there are issues there that the structural engineer calls for. You
try to get guys to understand the whys, but most don’t want to
know.” Although Painter said training programs have improved
in Florida in the past few years, in general, he feels that masons
aren’t given a lot of time for training because the pace of construction
is so fast: “They’re trained fast, they’re trained on the
job, and quality is secondary to productivity,” he said.
Tight schedules also increase construction problems in other
ways. Painter said that in many cases, his crew isn’t given enough
time to give the engineer the expected product. In fact, it’s not
uncommon to lay block in the morning and grout the same afternoon
because of scheduling. About two years ago, when the
industry had a problem keeping up with block production, his
crew actually laid block that was made the day before, then
grouted it later that afternoon.
Yaxley said a major problem is the lack of accountability for
quality control in the construction industry. As he put it, “The
contractor depends on the subcontractor, who depends on the
people working for them. Everyone depends on the inspector,
who doesn’t look, and the engineer and architect aren’t responsible.
What it comes down to is that nobody’s looking.” Yaxley
also said that it’s tough for the engineer to make the contractor
build according to plan. “The contractor gets upset … and the
owner gets his project delayed.”
Hart agreed with Yaxley. He compared criticizing the contractor
to making a citizen’s arrest. “You know it’s going to occupy
gobs and gobs of your time,” he said. “The whole system is
set up to make it very, very difficult to fulfill your obligation.”
THE SOLUTIONS
Some problems can be solved by the
structural engineer in practical ways. For
example, Cooper said that if engineers
specified the use of BIA’s documents, it
would reduce the likelihood of many of
these problems, including flashing, cracks,
arches, and mortar.
Borchelt suggested that engineers
could build a jobsite mock-up that includes
portions of the structural frame and all the
components of the exterior walls to make
sure the pieces fit together properly, that
they have a proper airspace, that they have
ties that provide proper embedment in the
masonry wythe as well as to the backing
system, and that there is a possibility to
keep that airspace clean as construction
goes on.
For masonry walls with reinforcement
and grout, the mock-up can be used to
verify proper placement. “Theoretically,
the contractor should discover any problems
or concerns in that jobsite mockup
that could then be corrected before they get on to the actual
construction itself,” he said. The mock-up is typically part of the
architectural requirements. Borchelt said, “The structural engineer
might notice whether it’s there or not, and if not, they
might suggest to the architect that they should include it.”
Perhaps more masonry education should be required in engineering
programs. Borchelt also suggested that engineers who
are less experienced with masonry projects could check out jobsites
and talk to experienced engineers so that they can design
buildings that are more constructible. “There’s nothing like getting
some experience beforehand,” he said. “Don’t let it happen
on your project — learn from the mistakes and the successes of
others.” However, Cooper cautions that people can be experienced
in building incorrectly and that knowledge of code
requirements and good practice (such as adhering to the BIA
documents) is also essential.
Painter thinks better coordination is needed between design
engineers. He said that because masonry systems are generally
held to tighter tolerances than other systems, structural engineers
should require electrical, mechanical, and HVAC engineers
to design their systems around structural masonry walls. “If the
red iron guy is going to be out of plumb, he can be out of plumb
in the other direction, away from us,” he said.
Painter also suggested that structural engineers specify 48 to
72 hours between laying block and grouting, which could help
with the time element masons face. And he said that the 1999
Masonry Standards Joint Committee “Code, Specification and
Commentaries,” which is referenced in the 2000 International
F i g u re 8: Inadequate metal ties between masonry and framing cause horizontal cracks, outward bowing, water
e n t ry, and risk of hazardous failure. Photo courtesy Norm L. Cooper, P. E .
14 • Interface June 2002
Building Code, could help alleviate construction
problems because it requires more inspections.
“Most people have felt over the past several years
that the cost of additional inspections would be
more than paid for by the eventual savings,” he said.
Borchelt said that requiring more training, such
as the program developed by the Bricklayers and
Allied Craftsmen Union and perhaps a certification
program could also help alleviate some of the construction
problems associated with masonry.
In fact, he said some states and cities,
including Michigan, St. Louis, and
Denver, have already taken the lead in
requiring training for masons and masonry
contractors, and Painter said Florida
developed an apprenticeship program
Figure 9: Inadequate drainage away from a building causes
foundation movement, which causes brick (step) cracks.
Photo courtesy Norm L. Cooper, P.E.
16 • Interface June 2002
Figure 10: Inadequate and sagging door header causing brick cracks. Photo courtesy Norm
L. Cooper, P.E.
Page 16
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about seven or eight years ago.
But other problems aren’t so easy to resolve and would
require major industry changes. For example, Hart believes that
owners should hire structural engineers to inspect construction
work. “The responsibility has to lie with structural engineers
because they’re the only ones who understand the impact,” he
said. The structural integrity may or may not be compromised
because the contractor is off by half an inch, but the structural
engineer is the only one who can make that decision. “I think
they should just charge the fee and do it right,” Hart said. And
Cooper said that, because city and private inspectors are rarely
required to be licensed professional engineers, only a very small
percentage of buildings are ever inspected by qualified structural
engineers. He said the benefit would far exceed the cost if
the codes required inspection by private-sector, licensed structural
engineers.
A BRIGHT FUTURE
Despite the issues involved with its construction, masonry
has many benefits, as seen by its strong history. It has tremendous
potential as a building material, one that combines structure
and finish. And masonry could be used even more frequently in
the future — especially if some of the problems identified here
are alleviated.
What do you think? Should engineering schools require
masonry classes? Should international building codes and local
governments require that owners hire licensed structural engineers
to inspect construction work? Should masons or masonry
contractors be certified? n
June 2002 Interface • 17
ABOUT THE AUTHOR
Cathy Murphy is the features editor
of Structural Engineer, a nationallydistributed,
business-to-business
magazine based in Alpharetta, Ga. A
former high school English teacher,
Murphy holds a bachelor’s degree in
English education and a master’s
degree in professional writing. She
may be contacted at featureseditor@
gostructural.com. CATHY MURPHY
Figure 11: Brick misalignments out of tolerance. Photo courtesy Norm L.
Cooper, P.E.
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