10 Masonry Wall Construction
TYPES OF MASONRY
WALLS
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
TYPES OF MASONRY WALLS
Composite Masonry Walls
• Multiwythe
– Outer wythe of stone, face brick, or
other durable masonry material
– Inner wythes of less expensive CMU or
clay units which do not require the same
level of durability or finish appearance
• Solid--no internal cavity
– Space between wythes is filled with
mortar
• Wythes are bonded with:
– Header units (in traditional construction)
– Metal ties or reinforcing (right)
• Most commonly associated with
traditional or historic masonry wall
construction
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
TYPES OF MASONRY WALLS
Masonry Cavity Walls
• Greater resistance to
water penetration than
solid or composite walls
• Multiwythe
• A continuous air space
between wythes acts as an
internal drainage plane.
• Water that penetrates the
outer wythe runs down
the cavity and then is
drained back to the
exterior.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
TYPES OF MASONRY WALLS
Masonry Cavity Walls
• Wall ties or veneer ties,
made of corrosion
resistant metal, span the
cavity and allow the inner
wythe to provide lateral
support to the, usually
thinner, outer wythe.
– Stainless steel: longest
lasting
– Galvanized (zinc-coated)
steel: less expensive
• Wall ties come in a great
variety of configurations.
In this illustration the ties
also serve to hold rigid
insulation boards snugly
against the inner wythe.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
TYPES OF MASONRY WALLS
Masonry Cavity Walls
• Flashings: Continuous
waterproof membranes
that intercept water in the
cavity and redirect it to
the exterior
• Weep holes: Allow water
to drain out from wall
• Dampproofing: Waterrepellent coatings applied
to the face of the inner
wythe to provide
additional resistance to
water penetration
• Right: The mastic air
barrier also serves as the
water-repellent coating.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
TYPES OF MASONRY WALLS
Masonry Cavity Walls
• The minimum
recommended cavity
depth is 2 inches, to
allow space for masons to
keep the cavity clear of
mortar droppings during
construction.
• Water-resistant rigid
insulation boards can be
inserted into the cavity.
But a minimum of 1 inch
of clear airspace should
be preserved.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
TYPES OF MASONRY WALLS
Masonry Cavity Walls
• Cavity drainage materials:
Materials inserted into
the cavity to catch mortar
droppings and prevent
obstruction of weep
holes
• Mortar droppings should
always be minimized, as
they form bridges across
the cavity that can allow
water to bridge the cavity
as well.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
TYPES OF MASONRY WALLS
Masonry Loadbearing Walls
• Carry gravity loads from other
parts of the building structure
(adjacent floors and roof)
• In modern construction, almost
always reinforced
– Greater strength
– Much improved resistance to
seismic forces
• May be composite or cavity
wall construction
– In loadbearing cavity walls, the
inner wythe is usually the
loadbearing wythe and the outer
wythe or veneer is nonstructural.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
10 Masonry Wall Construction
SPANNING SYSTEMS
FOR MASONRY
BEARING WALL
CONSTRUCTION
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPANNING SYSTEMS FOR MASONRY BEARING WALL CONSTRUCTION
Ordinary Construction
• Light wood frame
interior structure, with
noncombustible
masonry exterior walls
• Right:
– Cavity wall
– Loadbearing
– Reinforced CMU
interior wythe
– Brick exterior veneer
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPANNING SYSTEMS FOR MASONRY BEARING WALL CONSTRUCTION
Mill Construction
• Heavy timber interior
structure, with
noncombustible
masonry exterior walls
• Mill construction is
considered more fireresistant than ordinary
construction because
the heavy timbers are
slower burning than
the thinner framing
members of ordinary
construction.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPANNING SYSTEMS FOR MASONRY BEARING WALL CONSTRUCTION
Steel and Concrete Decks with
Masonry Bearing Walls
• Open-web steel joists,
corrugated steel decking, and
concrete floor slabs with
masonry bearing walls
• OWSJs are well suited to
masonry loadbearing
construction because of their
relatively close spacing which
imposes a more uniform load
on the masonry wall.
• With structural steel framing at
greater spacings, extra
reinforcing or enlarged
masonry piers may be required
to carry the greater
concentrated loads at bearing
points.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPANNING SYSTEMS FOR MASONRY BEARING WALL CONSTRUCTION
Steel and Concrete Decks
with Masonry Bearing
Walls
• Precast concrete
hollow core slabs with
cast-in-place concrete
topping
• The wall in this
example is singlewythe, fully grouted,
reinforced CMU
bearing wall.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPANNING SYSTEMS FOR MASONRY BEARING WALL CONSTRUCTION
Traditional Masonry
Loadbearing Wall
Construction
• Light wood joists
bearing on a traditional
solid brick masonry
wall
• Note the shallow arch
construction used to
span window openings.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPANNING SYSTEMS FOR MASONRY BEARING WALL CONSTRUCTION
Traditional Masonry
Loadbearing Wall
Construction
• Traditional masonry
structures are underreinforced by
contemporary standards
and often must be
structurally upgraded.
• Right: Steel straps and
perimeter steel angles tie
the floor to the exterior
wall to improve the
building's ability to
transfer seismic loads
from the unreinforced
masonry walls, to the
structural frame.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPANNING SYSTEMS FOR MASONRY BEARING WALL CONSTRUCTION
Traditional Masonry
Loadbearing Wall
Construction
• The floors and roofs
are tied to new,
structural steel framing
that is strategically
inserted into the
building and which can
carry the seismic loads
securely to the
foundation.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
10 Masonry Wall Construction
DETAILING
MASONRY WALLS
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage
• Flashings are built into
masonry walls to intercept
water that penetrates the wall
and direct the water back to
the exterior.
• Common materials include
various metals, synthetic
rubber or bituminous
membranes, and plastics.
• Materials should be chosen
with longevity in mind—
internal flashings must last as
long as the wall.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage: Metal
Flashings
• Most expensive and most durable
• Stainless steel (bottom)
–
–
–
Long-lasting
Non-staining
Stiffer and harder to form than
copper
• Copper (middle)
–
–
–
Long-lasting
Runoff from flashing can cause
staining by copper oxides
Softer and more easily formed than
stainless steel
• Galvanized (zinc-coated) steel
(top)
–
–
–
–
Less expensive
Less durable
Not recommended for permanent
internal flashings
OK for external, replaceable
flashings
• Aluminum (not shown)
–
Not recommended for masonry
walls because this metal reacts
chemically with the highly alkaline
mortar
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage:
Membrane Flashings
• Self-adhering bituminous
membranes (right)
– Polymer-modified bitumens
laminated to plastic backings
– Self-sticking to substrate
– Less expensive and easier to
install than metal flashings
– Have some capacity to selfseal around penetrations
– Cannot span cavities or other
significant gaps without
backup metal support
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage:
Membrane Flashings
• EPDM (right)
– Synthetic rubber
– Long-lasting
– Easy to install
• Other plastics
– May be vulnerable to tearing
or other deterioration
• Membrane flashings cannot
be permanently exposed to
sunlight. They are often
combined with metal where
flashings must project from
the wall.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage:
Composite Flashings
• Copper or other metals
laminated with heavy paper,
plastic film, or other
materials
• Material costs are less than
all-metal flashings because
the thinner metal sheets are
used.
• The laminating layers
provide added strength,
compensating for the thinner
sheet metal.
• Right: Copper laminated with
asphalt-saturated glass fabric
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage: Joining
and Sealing Flashings
• Where flashing sections
meet, the joints must be
made watertight.
• Metals are most permanently
joined and sealed by
soldering or welding. Sealing
with mastics is less expensive,
but also less permanent.
• Membrane and composite
flashings are sealed with
mastics (right) or adhesive
sealants.
• Self-adhering flashings are
lapped and self-adhered to
form a watertight seal.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage:
Flashing Locations
• A through-wall (internal)
flashing installed
underneath the top-ofwall coping units
intercepts water that
passes between joints of
those units.
• An external flashing, in
this case a
counterflashing, is
installed on the back of
the parapet to prevent
water from passing
behind and under the
roof membrane
termination.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage:
Flashing Locations
• Through-wall flashings
should be installed at all
interruptions in the
cavity.
• A flashing above a wall
opening intercepts water
in the cavity and prevents
it from spilling into the
opening.
• A flashing below a wall
opening intercepts water
that enters around the
opening and keeps it out
of the wall.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage:
Flashing Locations
• Where a metal angle
provides support to the
exterior brick wythe, a
flashing on top of the
angle intercepts water in
the cavity.
• The angle itself is not
sufficiently watertight
around its back and at its
ends to act as a flashing
on its own. The flashing
also protects the angle
from exposure to water
and corrosion.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage:
Flashing Locations
• A flashing at the base of
the wall intercepts water
in the cavity.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage:
Flashing Locations
• Flashings are also used in
composite walls, to
intercept water that
infiltrates the wall.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage:
Flashing Details
• The backs of flashings
are turned up to direct
captured water toward
the exterior of the wall.
• Flashing ends are turned
up and folded to form
end dams which prevent
water from spilling off
the ends of the flashing
into the cavity.
• Flashings under windows
and doors are often
called sill pans.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage:
Flashing Details
• Best practice: Flashings
should project beyond the
face of the wall at least ¾inch and angle downward,
so that water intercepted
by the flashing falls free of
the wall and does not cling
to the underside of the
flashing and seep back into
the wall.
• The exposed, projecting
end of the flashing must be
metal. Membranes and
composite materials are
not stiff enough and many
degrade under exposure to
sun light.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage:
Weeps
• A short length of rope
has been inserted into
the head joint between
masonry units to form a
weep.
• In some cases, the rope
will remain in the joint
after the wall is
completed, acting as a
wick to draw water
pooled on the flashing
out of the cavity.
• In other cases, the rope
is removed after the
mortar has hardened,
leaving a small opening.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Flashings and Drainage:
Weeps
• Weeps formed with a
small-diameter plastic
tube (above) and a preformed plastic insert
(below)
• Also below, the
bituminous flashing
membrane is creeping
out from between the
masonry bed joint. A
better practice is to finish
flashings with stiff metal
edges that can protrude
neatly from the wall
(above).
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Thermal Insulation
• Rigid foam, part of an
Exterior Insulation and
Finish System (EIFS),
can be applied to the
exterior side of a
masonry wall.
• With exterior insulation,
the thermal mass of the
masonry is coupled to
the interior conditioned
environment, and can
contribute to energy
savings in some
circumstances.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Thermal Insulation
• Rigid foam insulation can
be inserted into the
masonry wall cavity.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Thermal Insulation
• CMU cores can be
insulated with loose
granular insulation or rigid
foam inserts.
• The effectiveness of
insulation in CMU cores is
limited by thermal bridging
of the solid portions of the
CMUs, and by the absence
of insulation in cells where
reinforcing and grouting is
required.
• Bottom: Proprietary CMUs
with special foam inserts
can improve energy
efficiency by reducing
thermal bridging.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
DETAILNG MASONRY WALLS
Thermal Insulation
• A variety of types of
insulation can be applied
to the inner side of the
wall.
• Bottom: Rigid foam
boards being fastened to
the interior side of a
CMU wall using a
proprietary furring
system
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
10 Masonry Wall Construction
SPECIAL
PROBLEMS IN
MASONRY
CONSTRUCTION
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPECIAL PROBLEMS IN MASONRY CONSTRUCTION
Expansion and Contraction
• Masonry construction
expands and contracts
due to changes in
temperature, moisture
content, and structural
loading.
• Joints must be provided
to allow movement to
occur without causing
unsightly or detrimental
cracking:
– Where changes in
geometry create stress
concentrations (right)
– Close to corners
– At intervals no greater
than 125' in straight walls
– At changes in support
conditions
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPECIAL PROBLEMS IN MASONRY CONSTRUCTION
Expansion and
Contraction
• Joints are sealed at
the surface of the
wall, for appearance
considerations and to
prevent the
uncontrolled passage
of air and water.
• Some joint designs
restrict out-of-plane
movement between
adjacent wall sections
while permitting
expansion and
contraction in the
plane of the wall.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPECIAL PROBLEMS IN MASONRY CONSTRUCTION
Expansion and Contraction
• Vertical expansion joints
in brick veneer on either
side of stacked window
openings
• A flexible sealant
material that can expand
and contract with
movement is applied to
the joint.
• Sealant color can be
chosen to match that of
the mortar and sand can
be cast into the surface
of the sealant before it
cures, to imitate the
appearance of a mortar
joint.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPECIAL PROBLEMS IN MASONRY CONSTRUCTION
Expansion and Contraction
• Brick expands slightly over time
as it absorbs moisture from the
atmosphere.
• Many structural systems,
especially those of concrete,
shrink slightly over time due to
long term effects of structural
loads.
• On multistory buildings,
horizontal expansion joints must
be provided in brick veneer to
allow gradual expansion of the
brick.
• If these joints are omitted, the
veneer will gradually become
compressed, bow outward, and
eventually fail.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPECIAL PROBLEMS IN MASONRY CONSTRUCTION
Expansion and Contraction
• The thin, horizontal white
lines are expansion joints
in the brick veneer located
approximately level with
the floor structure behind
from which the veneer is
supported.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPECIAL PROBLEMS IN MASONRY CONSTRUCTION
Expansion and Contraction
• A close-up of one of the
expansion joints in the last
image
• Note the weep hole.
• This joint does not follow best
practices:
– The internal flashing does not
project beyond the face of the
wall.
– The joint is not wide enough to
accommodate significant
movement in the veneer without
risking failure of the sealant joint
or overstressing of the veneer.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPECIAL PROBLEMS IN MASONRY CONSTRUCTION
Expansion and Contraction
• Horizontal and vertical
expansion joints are
provided where changes in
the supporting structure are
likely to cause differential
movements in the veneer.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPECIAL PROBLEMS IN MASONRY CONSTRUCTION
Efflorescence
• White crystalline deposits
occur on the surface of
masonry when moisture
within carries salts from the
mortar or masonry units to
the surface and then
evaporates, leaving the salts
behind.
• Efflorescence is most
common with new masonry
and usually decreases over
time.
• It can be minimized by
avoiding contaminants in
the masonry ingredients,
and by keeping water out of
the wall both during and
after construction.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPECIAL PROBLEMS IN MASONRY CONSTRUCTION
Mortar Joint Deterioration
• Water and freeze/thaw
action deteriorate mortar
joints over time.
• Repointing: Deteriorated
mortar is cut out and the
joints are refinished with
fresh mortar.
• Care must be exercised
that the new mortar is
not harder or more
brittle than the mortar in
the remainder of the
joint, or early mortar
failure or damage to the
bricks themselves can
result.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPECIAL PROBLEMS IN MASONRY CONSTRUCTION
Moisture Resistance of
Masonry
• Cavity wall construction
limits water passage
through masonry walls.
• Various water repellent
coatings, either clear or
opaque, can be applied
to the wall surface. But
coatings should be
breathable to allow
moisture that does
infiltrate the wall to
escape.
• Mortar and concrete for
CMUs can be mixed with
additives that increase
their water repellency
(right).
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.
SPECIAL PROBLEMS IN MASONRY CONSTRUCTION
Cold and Hot Weather
Construction
• Mortar must not freeze
while it is curing:
– Keep materials dry.
– Preheat materials.
– Protect construction from
weather and wind.
– Use cement types that cure
rapidly and generate more
heat while curing.
– Provide temporary space
heating.
• In especially hot weather,
mortar should be protected
from water loss:
– Keep mortar in shade to
prevent rapid water
evaporation.
– Pre-wet masonry units to
prevent excessive water
absorption.
Fundamentals of Building Construction, Materials & Methods, 5th Edition
Copyright © 2009 J. Iano. All rights reserved.