Expansion joints are used in brickwork to accommodate movement and to avoid cracking. This Technical Note
describes typical movement joints used in building construction and gives guidance regarding their placement. The theory and
rationale for the guidelines are presented. Examples are given showing proper placement of expansion joints to avoid cracking
of brickwork and methods to improve the aesthetic impact of expansion joints. Also included is information about bond breaks,
bond beams and flexible anchorage.
differential movement, expansion joints, flexible anchorage, movement, sealants.
1850 Centennial Park Drive, Reston, Virginia 20191
• For brickwork without openings, space no more than 25 ft
(7.6 m) o.c.
• For brickwork with multiple openings, consider symmetrical
placement of expansion joints and reduced spacing of no
more than 20 ft (6.1 m) o.c.
• When spacing between vertical expansion joints in para-
pets is more than 15 ft (4.6 m), make expansion joints
wider or place additional expansion joints halfway between
full-height expansion joints
• Place as follows:
- at or near corners
- at offsets and setbacks
- at wall intersections
- at changes in wall height
- where wall backing system changes
- where support of brick veneer changes
- where wall function or climatic exposure changes
• Extend to top of brickwork, including parapets
Horizontal Expansion Joints in Brick Veneer:
• Locate immediately below shelf angles
• Minimum ¼ in. (6.4 mm) space or compressible material
recommended below shelf angle
• For brick infill, place between the top of brickwork and
• Accommodate brickwork movement by:
- placing expansion joints around elements that are rigidly
attached to the frame and project into the veneer, such
as windows and door frames
- installing metal caps or copings that allow independent
vertical movement of wythes
- installing jamb receptors that allow independent
movement between the brick and window frame
• Comply with ASTM C 920, Grade NS, Use M
• Class 50 minimum extensibility recommended; Class 25
• Consult sealant manufacturer’s literature for guidance
regarding use of primer and backing materials
• Use building paper or flashing to separate brickwork from
dissimilar materials, foundations and slabs
• Use reinforcement to accommodate stress concentrations,
particularly in parapets, at applied loading points and
• Consider effect of vertical expansion joints on brickwork
© 2006 Brick Industry Association, Reston, Virginia
Page 1 of 11
A system of movement joints is necessary to accommodate the changes in volume that all building materials
experience. Failure to permit the movements caused by these changes may result in cracks in brickwork, as
discussed in Technical Note 18. The type, size and placement of movement joints are critical to the proper
performance of a building. This Technical Note defines the types of movement joints and discusses the proper
design of expansion joints within brickwork. Details of expansion joints are provided for loadbearing and
nonloadbearing applications. While most examples are for commercial structures, movement joints, although rare,
also must be considered for residential structures.
The primary type of movement joint used in brick construction is the expansion joint. Other types of movement
joints in buildings that may be needed include control joints, building expansion joints and construction joints. Each
of these is designed to perform a specific task, and they should not be used interchangeably.
Brick Industry Association
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temperature, moisture expansion, elastic deformation, settlement and creep. Expansion joints may be horizontal
or vertical. The joints are formed by leaving a continuous unobstructed opening through the brick wythe that may
be filled with a highly compressible material. This allows the joints to partially close as the brickwork expands.
Expansion joints must be located so that the structural integrity of the brickwork is not compromised.
A control joint determines the location of cracks in concrete or concrete masonry construction due to volume
changes resulting from shrinkage. It creates a plane of weakness that, in conjunction with reinforcement or joint
reinforcement, causes cracks to occur at a predetermined location. A control joint is usually a vertical gap through
the concrete or concrete masonry wythe and may be filled with inelastic materials. A control joint will tend to
open rather than close. Control joints must be located so that the structural integrity of the concrete or concrete
masonry is not affected.
A building expansion joint is used to separate a building into discrete sections so that stresses developed in one
section will not affect the integrity of the entire structure. The building expansion joint is a through-the-building joint
and is typically wider than an expansion or control joint.
A construction joint (cold joint) occurs primarily in concrete construction when construction work is interrupted.
Construction joints should be located where they will least impair the strength of the structure.
Although the primary purpose of expansion joints is to
accommodate expansive movement, the joint also must resist
water penetration and air infiltration. A premolded foam or
neoprene pad that extends through the full wythe thickness
aids in keeping mortar or other debris from clogging the joint
and increases water penetration resistance. Fiberboard and
similar materials are not suitable for this purpose because
they are not as compressible.
Mortar, ties or wire reinforcement should not extend into
or bridge the expansion joint. If this occurs, movement will
be restricted and the expansion joint will not perform as
intended. Expansion joints should be formed as the wall is
built, as shown in
. However, vertical expansion joints
Sealants are used on the exterior side of expansion joints to prevent water and air penetration. Many different
types of sealants are available, although those that exhibit the highest expansion and compression capabilities
are best. Sealants should conform to ASTM C 920, Standard Specification for Elastomeric Joint Sealants [Ref. 1],
Grade NS, Use M, and be sufficiently compressible, resistant to weathering (ultraviolet light) and bond well to
adjacent materials. Sealant manufacturers should be consulted for the applicability of their sealants for expansion
joint applications. Compatibility of sealants with adjacent materials such as brick, flashings, metals, etc., also
must be taken into consideration. Manufacturers recommend three generic types of elastomeric sealants for use
on brickwork: polyurethanes, silicones and polysulfides. Most sealants suitable for use in brickwork expansion
joints meet an ASTM C 920 Class 25 or Class 50 rating that requires them to expand and contract by at least
25 percent or 50 percent of the initial joint width, respectively. Sealants meeting Class 50 are recommended to
minimize the number of joints. Many sealants require a primer to be applied to the masonry surface to ensure
Use a circular foam backer rod behind sealants to keep the sealant at a constant depth and provide a surface
to tool the sealant against. The sealant must not adhere to the backer rod. The depth of the sealant should be
approximately one-half the width of the expansion joint, with a minimum sealant depth of
in. (6.4 mm).
Vertical Expansion Joint Construction
expansion joints with either a premolded foam pad, a
neoprene pad or a backer rod.
While generally limited to rain screen walls, a two-stage
joint as shown in
can increase resistance to
water and air infiltration. This type of joint provides a
vented or pressure-equalized joint. The space between
the sealants must be vented toward the exterior to allow
drainage. This is typically achieved by leaving a hole or
gap in the exterior sealant joint at the top and bottom of
No single recommendation on the positioning and spacing
of expansion joints can be applicable to all structures.
Review each structure for the extent of movements
expected. Accommodate these movements with a
series of expansion joints. Determine the spacing of
expansion joints by considering the amount of expected
wall movement, the size of the expansion joint and the
compressibility of the expansion joint materials. In addition
to the amount of anticipated movement, other variables
that also may affect the size and spacing of expansion
joints include restraint conditions, elastic deformation
due to loads, shrinkage and creep of mortar, construction
tolerances and wall orientation.
The theory and equation for estimating the anticipated extent of unrestrained brick wythe movement are presented
in Technical Note 18. Estimated movement is based on the theoretical movement of the brickwork attributed to
each property and expressed as coefficients of moisture expansion (k
), thermal expansion (k
) and freezing
). As discussed in Technical Note 18, for most unrestrained brickwork, the total extent of movement
can be estimated as the length of the brickwork multiplied by 0.0009. A derivative of this equation can be written to
calculate the theoretical spacing between vertical expansion joints as follows:
= spacing between expansion joints, in. (mm)
= width of expansion joint, typically the mortar joint width, in. (mm)
= percent extensibility of expansion joint material
The expansion joint is typically sized to resemble a mortar joint, usually
in. (10 mm) to
in. (13 mm). The width
of an expansion joint may be limited by the sealant capabilities. Extensibility of sealants in the 25 percent to 50
percent range is typical for brickwork. Compressibility of filler materials may be up to 75 percent.
Example. Consider a typical brick veneer with a desired expansion joint size of
in. (13 mm) and a sealant with
50 percent extensibility. Eq. 1 gives the following theoretical expansion joint spacing:
Therefore, the maximum theoretical spacing between vertical expansion joints in a straight wall would be 23 ft
- 2 in. (7.1 m). This spacing does not take into account window openings, corners or properties of other materials
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Premolded Foam Pad
Sealant & Backer Rod
4 of 11
In most instances it is desirable to be conservative,
but it may be economically desirable to exceed the
theoretical maximum spacing as a calculated risk. For
example, calculations may result in a theoretical spacing
of expansion joints every 23 ft – 2 in. (7.06 m) but the
actual expansion joint spacing is set at 24 ft (7.3 m)
to match the structural column spacing or a specific
modular dimension. Vertical expansion joint spacing
should not exceed 25 ft (7.6 m) in brickwork without
The actual location of vertical expansion joints in a
structure is dependent upon the configuration of the
structure as well as the expected amount of movement.
In addition to placing an adequate number of expansion
joints within long walls, consider placing expansion joints
at corners, offsets, openings, wall intersections, changes
in wall heights and parapets.
juncture, typically causing distress on one or both sides
of a corner, as shown in
. Place expansion
joints near corners to alleviate this stress. The best
location is at the first head joint on either side of the
corner; however, this may not be aesthetically pleasing.
Masons can typically reach about 2 ft (600 mm) around
the corner from the face where they are working. An
expansion joint should be placed within approximately
10 ft (3 m) of the corner in either wall, but not necessarily
both. The sum of the distance from a corner to the
adjacent vertical expansion joints should not exceed
the spacing of expansion joints in a straight wall,
as shown in
. For example, if the spacing
between vertical expansion joints on a straight wall is
25 ft (7.6 m), then the spacing of expansion joints around
a corner could be 10 ft (3.0 m) on one side of the corner
and 15 ft (4.6 m) on the other side.
an offset, rotating the shorter masonry leg, or causing
cracks within the offset, as shown in
expansion joints at the offset to allow the parallel walls to
illustrates. Expansion joints placed
at inside corners are less visible.
is too large, cracks may develop at window and door
openings. In structures containing punched windows and
door openings, more movement occurs in the brickwork
above and below the openings than in the brickwork
between the openings. Less movement occurs along
the line of openings since there is less masonry. This
differential movement may cause cracks that emanate
from the corners of the opening, as in
pattern of cracking does not exist in structures with
continuous ribbon windows.
Cracking in Structure with “Punched”
Windows, Without Proper Expansion Joints
+ < Typ. Spacing
Between Expansion Jts.
Movement at Corner Without Expansion Joints
_ 10 ft.
Direction of Expansion
Proper Expansion Joint Locations at Offset
Direction of Expansion
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“natural” expansion joints. One alternative is to place
expansion joints halfway between the windows. This
requires a sufficiently wide section of masonry between
the openings, typically 4 ft (1.2 m). It is often desirable
to locate vertical expansion joints along the edge or
jamb of the opening. In cases where the masonry above
an opening is supported by shelf angles attached to
the structure, a vertical expansion joint can be placed
alongside the opening, continuing through the horizontal
If a vertical expansion joint runs alongside an opening
spanned by a loose lintel as shown in
, the loose
steel lintel must be allowed to expand independently of
the masonry. A slip plane should be formed by placing
flashing above and below the angle. Mortar placed in front
of the lintel is subject to cracking; thus, a backer rod and
sealant should be used, as shown in
steel expands more than masonry, a
in. (3.2 to 6.4
mm) space should be left at each end of the lintel. These
measures form a pocket that allows movement of the
steel angle within the brickwork. Locating the expansion
joint adjacent to the window will influence the dead weight
of the masonry bearing on the lintel. Instead of the usual
triangular loading, the full weight of the masonry above
the angle should be assumed to bear on the lintel. See
design. If a vertical expansion joint cannot be built in this
manner, do not place it alongside the opening.
Junctions. Expansion joints should be located at
junctions of walls with different environmental exposures
or support conditions. Separate portions of brickwork
exposed to different climatic conditions should be
separated with expansion joints since each area will
move differently. An exterior wall containing brickwork
that extends through glazing into a building’s interior
should have an expansion joint separating the exterior
brickwork from the interior brickwork. You may need
to use expansion joints to separate adjacent walls of
different heights to avoid cracking caused by differential
movement, particularly when the height difference is very
large. Examples are shown in
side are exposed on three sides to extremes of moisture
and temperature and may experience substantially
different movement from that of the wall below. Parapets
also lack the dead load of masonry above to help resist
movement. Therefore, extend all vertical expansion joints
through parapets. Since parapets are subject to more
movement than the wall below, they must be treated
differently. When vertical expansion joints are spaced
more than 15 ft (4.6 m) apart, the placement and design of
expansion joints through parapets need to accommodate
this additional movement. In this situation, make
Steel Lintel Beyond
Backer Rod and
Different Support Conditions
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These additional expansion joints must continue down to a horizontal expansion joint.
As a third alternative, install
Although expansion joints are usually noticeable on flat
walls of masonry buildings, there are ways to reduce
their visual impact. Architectural features such as quoins,
recessed panels of brickwork or a change in bond pattern
reduce the visual impact of vertical expansion joints. In
some cases, it may be desirable to accentuate the location
of the expansion joint as a design detail. This is possible by
recessing the brickwork at the expansion joint, or by using
special-shaped brick units as shown in
Colored sealants that match the brick in running bond, or
the mortar in stack bond, help to hide vertical expansion
joints. Mason’s sand also can be rubbed into new
sealant to remove the sheen, making the joint blend in
more. Expansion joints also are less noticeable when located at inside corners. Hiding expansion joints behind
downspouts or other building elements can inhibit maintenance access and is not advised. Toothing of expansion
joints to follow the masonry bond pattern is not recommended. It is more difficult to keep debris out of the joint
during construction; such debris could interfere with movement. Further, most sealants do not perform well when
subjected to both shear and tension.
Symmetrical placement of expansion joints on the elevation of buildings is usually most aesthetically pleasing.
Further, placing the expansion joints in a pattern such that wall areas and openings are symmetrical between
expansion joints will reduce the likelihood of cracking.
Location of vertical expansion joints will be influenced by additional factors. Spandrel sections of brickwork
supported by a beam or floor may crack because of deflection of the support. Reduced spacing of expansion
joints will permit deflection to occur without cracking the brickwork.
allow anchored masonry veneer with an installed weight not exceeding 40 lb/ft
(1,915 Pa) and a maximum height
the veneer supported by wood from the veneer supported by the foundation.
Horizontal expansion joints are typically needed if the
brick wythe is supported on a shelf angle attached to the
frame or used as infill within the frame. Placing horizontal
expansion joints below shelf angles provides space for
vertical expansion of the brickwork below and deformation
of the shelf angle and the structure to which it is attached.
Structures that support the brick wythe on shelf angles,
usually done for each floor, must have horizontal expansion
joints under each shelf angle.
shows a typical
detail of a horizontal expansion joint beneath a shelf angle.
If the shelf angle is not attached to the structure when the
brick below it are laid, any temporary shims that support the
angle must be removed after the shelf angle is connected.
The joint is formed by a clear space or highly compressible
material placed beneath the angle, and a backer rod and
Sealant and Backer Rod
on Bolt Heads
Expansion Joint at Shelf Angle
joint locations. However, shelf angles must be discontinuous to provide for their own thermal expansion. A space
of ¼ in. in 20 ft (6 mm in 6 m) of shelf angle length is typically sufficient. Bolt heads anchoring a shelf angle to the
structure should be covered to decrease the possibility of flashing puncture.
The size of the horizontal expansion joint should take into account movements of the brickwork and movements
of the frame. Frame movements include both material and load-induced movements, such as deflections of
the shelf angle, rotation of the horizontal leg of the shelf angle, and movement of the support from deflection,
temperature change, shrinkage, creep or other factors.
When a large horizontal expansion joint is necessary, a lipped brick course may be used to allow movement while
minimizing the aesthetic impact of the joint. To avoid problems with breakage, the height and depth of the lipped
portion of the brick should be at least ½ in. (13 mm). Lipped brick should be made by the brick manufacturer for
quality assurance purposes.
Construction using lipped brick requires careful
consideration of the frame movements noted
previously. Allowance for adjacent material tolerances
including the building frame should also be considered.
Adequate space should be provided between the
lipped portion of the brick and the shelf angle to ensure
no contact. Contact should not occur between the
lipped brick and the brickwork below the shelf angle
or between the lip of the brick and the shelf angle, not
only during construction, but also throughout the life of
Lipped brick may be installed as the first course above
a shelf angle, as shown in
. Flashing should
be placed between the shelf angle and the lipped brick
course. Proper installation of flashing is made more
difficult because the flashing must conform to the shape
of the lip. This shape may be achieved with stiffer
flashing materials such as sheet metal. If the specified
flashing materials are made of composite, plastic or
rubber, a sheet metal drip edge should be used. The
practice of placing flashing one course above the shelf
angle is not recommended, as this can increase the
potential for movement and moisture entry.
Lipped brick also may be inverted and placed on the
last course of brickwork below a shelf angle, as shown
. While installing an inverted lipped brick
course allows the flashing of the brickwork above to
maintain a straight profile through the brickwork, it also
allows the lipped brick course to move independent
of the shelf angle. Thus, there is an increased
possibility of the shelf angle coming in contact with
the lipped brick course, resulting in cracking at the lip.
It is difficult, if not impossible, to install compressible
material below the shelf angle. Further, it is likely that
temporary shims may be left in place between the lipped
brick and the shelf angle.
Horizontal expansion joints are also recommended
when brick is used as an infill material within the frame of the structure. Expansion joints must be provided
between the top course of brickwork and the member above. Deflections of the frame should be considered when
sizing the expansion joint to avoid inadvertently loading the brickwork.
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Inverted Lipped Brick
on Bolt Heads
Min. 1/4 in. (6 mm) Thick
on Bolt Heads
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Some buildings with brick veneer construction do not support the brickwork on shelf angles. These typically include
low-rise buildings constructed with wood and steel stud framing and buildings with shear walls. Building Code
Requirements for Masonry Structures limits brick veneer with wood or steel stud backing to a height of 30 ft (9 m)
to the top plate and 38 ft (12 m) to the top of a gable. Brick veneer with a rigid backing of concrete or concrete
masonry has no such limitation in the code. Brick veneer with this rigid backing may be supported by the foundation
without intermediate shelf angles to a recommended maximum height of about 50 ft (15 m), provided the building is
Anchorage to Steel Beam (section)
or Wall (section)
with Eye & Pintle
Page 9 of 11
properly. In these buildings, differential movement is accommodated by the anchor or tie system, window details,
detailing at top of the wall and where other building components pass through the brickwork. These details must
provide independent vertical movement between the brickwork and the backing. Building components that extend
into or through the brick veneer (e.g., windows, doors, vents, etc.) also must be detailed to allow independent
vertical movement of the brick veneer and the component. The structural frame or backing provides the brick
veneer with lateral support and carries all other vertical loads. The veneer is anchored by flexible connectors or
adjustable anchors that permit differential movement. Allowance for differential movement between the exterior
brickwork and the adjacent components should be provided at all openings and at the tops of walls. Vertical
expansion joints also must be incorporated, as discussed in previous sections of this Technical Note.
Connectors, anchors or ties that transfer load from the brick wythe to a structural frame or backing that
provides lateral support should resist movement perpendicular to the plane of the wall (tension and
compression) but allow movement parallel to the wall without becoming disengaged. This flexible anchorage
permits differential movements between the structure and the brickwork.
shows typical methods
for anchoring masonry walls to columns and beams. Technical Note 44B provides detailed information about
masonry ties and anchors.
The size and spacing of anchors and ties are based on tensile and compressive loads induced by lateral loads
on the walls or on prescriptive anchor and tie spacing requirements in building codes. Technical Note 44B lists
recommended tie spacing based on application.
There must be sufficient clearance among the masonry elements and the beams and columns of the structural
frame to permit the expected differential movement. The masonry walls may be more rigid than the structural
frame. This clearance provides isolation between the brickwork and frame, allowing independent movement.
Movement joints must be provided in multi-wythe brick and
concrete masonry walls. Expansion joints are placed in the
brick wythe, and control joints are placed in the concrete
masonry, although they do not necessarily have to be
aligned through the wall.
Concrete and concrete masonry have moisture and
thermal movements that are considerably different from
those of brick masonry. Floor slabs and foundations also
experience different states of stress due to their loading
and support conditions. Therefore, it may be necessary
to separate brickwork from these elements using a bond
break such as building paper or flashing. Such bond
breaks should be provided between foundations and
walls; between slabs and walls; and between concrete
and clay masonry, to allow independent movement while
still providing gravity support. Typical methods of breaking
bond between walls and slabs, and between walls and
foundations are shown in
When bands of clay brick are used in concrete masonry
used in clay brick walls, differences in material properties
may cause mortar joints or masonry units to crack. Such
problems can be easily avoided by using bands of brickwork featuring brick of a different color, size or texture or
a different bond pattern. If, however, a different material is used for the band, it may be prudent to install a bond
break between the two materials, provide additional movement joints in the wall, or place joint reinforcement in the
bed joints of the concrete masonry to reduce the potential for cracking.
Bond Breaks in Loadbearing Cavity Wall
compressive strength of the wall and should not affect
the stability of the veneer wythe when anchored properly.
The weight of the masonry, additional anchorage and
the frictional properties at the interface provide stability.
Sealant at the face of the joints between the different
materials will reduce possible water entry. If the band is
concrete masonry or cast stone, additional control joints are
recommended in the band. If the band is a single course,
there is a likelihood of vertical cracks at all head joints.
These can be closed with a sealant. Bands of two or more
courses should include horizontal joint reinforcement in
the intervening bed joints, as shown in
The potential for cracking in loadbearing masonry
members is less than in nonloadbearing masonry
members because compressive stresses from dead and
Sealant in Raked Joint
and Adjustable Anchor
in CMU Veneer Band
Bond Break Material
Bond Break at Foundation
Hollow Brick Construction
points of load application and around openings to accommodate or distribute high stresses will also help control
the effects of movement. Reinforcement may be placed in bed joints or in bond beams, as shown in
Historic loadbearing structures were not constructed with expansion joints. However, these walls were made of
When it is necessary to anchor a masonry wall to a foundation or to a roof, it is still possible to detail the walls in a
manner that allows some differential movement, as shown in
required for loadbearing walls subjected to high winds or seismic forces.
This Technical Note defines the types of movement joints used in building construction. Details of expansion joints
used in brickwork are shown. The recommended size, spacing and location of expansion joints are given. By using
the suggestions in this Technical Note, the potential for cracks in brickwork can be reduced.
Expansion joints are used in brick masonry to accommodate the movement experienced by materials as they
react to environmental conditions, adjacent materials and loads. In general, vertical expansion joints should be
used to break the brickwork into rectangular elements that have the same support conditions, climatic exposure
and through-wall construction. The maximum recommended spacing of vertical expansion joints is 25 ft (7.6 m).
Horizontal expansion joints must be placed below shelf angles supporting brick masonry.
1. ASTM C 920, Standard Guide for Use of Elastomeric Joint Sealants, Annual Book of Standards, Vol.
04.07, ASTM International, West Conshohocken, PA, 2006.
Masonry Design and Detailing for Architects, Engineers and Contractors, Fifth Edition, McGraw
Hill, Inc., New York, NY, 2003.
3. Beall, C., “Sealant Joint Design,” Water on Exterior Building Walls: Problems and Solutions, ASTM STP
1107, T.A. Schwartz, Ed., ASTM, West Conshohocken, PA, 1991.
4. Building Code Requirements for Masonry Structures (ACI 530-05/ASCE 5-05/TMS 402-05), The Masonry
Society, Boulder, CO, 2005.
5. “Building Movements and Joints,” Portland Cement Association, Skokie, IL, 1982.
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