NCMA TEK
National Concrete Masonry Association
an information series from the national authority on concrete masonry technology
CONCRETE MASONRY
CORNER DETAILS
TEK 5-9A
Details
Keywords: architectural details, construction details,
corners, modular coordination, unit shapes
INTRODUCTION
A building's corners are typically constructed first, then
the remaining wall section is filled in. Because they guide the
construction of the rest of the wall, building the corners
requires special care. It is essential that the corner be built as
shown on the foundation or floor plan to maintain modular
dimensions.
For maximum construction efficiency and economy,
concrete masonry elements should be designed and constructed
with modular coordination in mind. Corners, however, present
unique situations, because the actual widths of standard units
are 3 5/8, 5 5/8, 7 5/8, 9 5/8 and 115/8 in. (92, 143, 194, 244 and
295 mm). In order to maintain an 8-in. (203-mm) module,
special corner details have been developed to accommodate
most typical situations.
Bay window or 8 in.
(203 mm) 45° angle
45° Outside corner unit
Figures 2 through 6 show how corners can be constructed
to minimize cutting of units while maintaining modularity of
the construction. Vertical steel, while not always required, is
often used at corner intersections.
UNITS
Unlike stretcher units, units used in corner construction
have square ends (see Figure 1). In addition, all-purpose or
kerf units are available, with two closely spaced webs in the
center that allow the unit to be easily split on the jobsite,
facilitating corner construction. Other special units may also
be available, such as bevelled-end units, forming a 45° angle
with the face of the unit, which are used to form walls
Double corner or
plain-end unit
45° Inside corner unit
All-purpose, kerf
or splitter unit
Single corner unit
Bevelled or mitered unit
Return corner unit
Figure 1—Concrete Masonry Units Used for Corner Construction
TEK 5-9A © 2004 National Concrete Masonry Association (replaces TEK 5-9)
(2004)
12 in.
(305 mm)
15 5
(39 / 8in.
7m
m)
.
5 8in )
3 / mm
(92
8 in.
(203 mm)
.
5/ 8in
11 mm)
5
(29
3 5
(92 /8in
mm .
)
.
5/ 8in
e
35
(92 /8in
mm .
)
15 mm)
7
(39
35
(92 /8in
mm .
)
.
5/ 8in
15 mm)
7
(39
.
5 8in
7 / mm)
4
(19
15 5
(39 / 8in.
7m
m)
it to
t un
Cu
12 in.
(305 mm)
Corner return
unit
75
(19 /8in
4m .
m)
.
5 8in
3 / mm)
(92
11 5
(29 / 8in.
5m
m)
.
5 8in )
3 / mm
(92
fit
.
5 8in
7 / mm)
4
(19
15 5
(39 / 8in.
7m
m)
7 5
(19 / 8in
4m .
m)
.
5/ 8in
15 mm)
7
(39
Bevelled unit
Figure 2—Corner Details, 4 Inch (102 mm) Walls
Cut unit to fit or use nominal
14 in. (356 mm) units
8 in.
(203 mm)
5 5
(14 / 8in
3m .
m)
13 5
(34 / 8in.
6m
m)
.
5/ 8in
)
3
1
mm
6
4
(3
.
5 8in
5 / mm)
3
(14
8 in.
(203 mm)
15
(39 /58in
7m .
(19 7 /58in m)
4m .
m)
.
5 8in
7 / mm)
4
(19
.
5/ 8in
)
15 7 mm
9
3
(
8 in. (203 mm) Wall to 8 in. (203 mm) Wall
Using Standard Units
Cut unit to fit or use nominal 14 in. (356 mm) units
15
(39 /58in.
7m
m)
10 in.
(254 mm)
7 5
(19 / 8in
4m .
m)
15 5
(39 / 8in.
7m
m)
.
5/ 8in
15 mm)
7
.
(39
5 8in
7 / mm)
4
(19
Corner return
unit
Figure 3—Corner Details, 6 Inch
(152 mm) Walls
.
5/ 8in
15 mm)
7
(39
7 5
(19 / 8in.
4m
m)
4 in. (102 mm)
thick half-length
unit
15 5
(39 / 8in.
7m
m)
Alternate
courses
.
5/ 8in
15 mm)
7
(39
.
5 in
7 / 8 m)
m
4
(19
8 in. (203 mm) Wall to 12 in. (305 mm) Wall
Figure 4—Corner Details, 8 Inch (203 mm) Walls
6 in.
(152 mm)
15
(39 /58in
.
7m .
5 / 8 in
m)
11 mm)
5
11
(29 5 in.
/8
(29 /5 8in.
15 mm)
5m
7
m)
(39
n.
5 8i
9 / mm)
4
(24
15
(39 /58in
.
7
9
(24 /58 in mm)
4m .
m)
.
5/ 8 in
11 mm)
5
(29
4 in.
(102 mm)
.
5 8in
/
15 mm)
7
(39
(for unreinforced corners only)
(for unreinforced corners only)
6 in.
(152 mm)
15
(39 /58in
n.
7m .
5 8i
Cut unit to fit
9 / m)
m)
or use nominal
m
4
9 /5 (24 5 8in.
14
in. (356
/
8 in
(24 .
15 mm)
Cut unit to fit
mm) units
4m
7
9
m) (3
or use nominal
14 in. (356 mm)
units
(for unreinforced corners only)
11
(29 /5 8in
5m .
m)
3 /5
(92 8in.
mm
)
6 in.
(152 mm)
15
(39 /58 in
7m .
m)
(19 7 /58in
4m .
m)
.
5 8in
/
15 mm)
7
(39
1 5 8 x 5 5 8 x 7 5 8 in.
(41 x 143 x 194 mm)
15
(39 /5 8in
7m .
m)
15
n.
5 8i
7 / mm)
4
(19
5
8 x 5 8 x 7 8 in.
(41 x 143 x 194 mm)
15
(39 /58in
7m .
m)
15
(39 /58 in
7m .
m)
Alternate
courses
.
/ in
15 mm)
7
(39
5 8
(19 7 /58in
4m .
m)
.
5 / 8 in )
11 5 mm
(29
n.
5 8i
7 / mm)
4
(19
.
5 8in
/
15 mm)
7
(39
3 5/8 x 3 5/8 x 7 5/8 in.
(92 x 92 x 194 mm)
.
5 8in
/
15 mm)
7
(39
5
.
5 / 8 in
)
11 5 mm
9
(2
4 in.
(102 mm)
n.
5 8i
7 / mm)
4
(19
15
(39 /58in.
7m
(19 7 /58in m)
4m .
m)
.
5 8in
3 / mm)
2
(9
Figure 5—Corner Details, 10 Inch (254 mm) Walls
15
(39 /5 8in.
7m
m)
.
5/ 8in
15 mm)
7
(39
(19 7 /58in
4m .
m)
Alternate
courses
.
5/ 8in
15 mm)
7
(39
.
5 8in
7 / mm)
4
(19
Figure 6—Corner Details, 12 Inch (305 mm) Walls
intersecting at 135° angles. The Concrete Masonry Shapes
and Sizes Directory (ref. 2) contains illustrations of additional
corner units, including those with architectural surfaces. Units
in adjacent courses overlap to form a running bond pattern at
the corner. Architectural units, such as those with split or
scored faces, are often available with the architectural finish
on two sides to accommodate corner construction.
Local manufacturers should be contacted for information
on unit availability.
CODE PROVISIONS FOR INTERSECTING WALLS
Building Code Requirements for Masonry Structures
(ref. 4) stipulates three options to transfer stresses from one
wall to another at wall intersections, each requiring the
masonry to be laid in running bond. These three options are
via: running bond; steel connectors; and bond beams. Corner
construction lends itself to providing shear transfer by relying
on running bond. Running bond (defined as the placement of
masonry units such that head joints in successive courses are
horizontally offset at least one-quarter the unit length) ensures
there is sufficient unit interlock at the corner to transfer shear.
When any of these conditions are not met, the transfer of shear
forces between walls is required to be prevented.
REFERENCES
1 . Annotated Design and Construction Details for
Concrete Masonry, TR 90B. National Concrete
Masonry Association, 2003.
2 . Concrete Masonry Shapes and Sizes Directory, CM260A.
National Concrete Masonry Association, 1997.
3 . Reinforced Concrete Masonry Inspector's Handbook, 4th
edition. Masonry Institute of America, 2002.
4 . Building Code Requirements for Masonry Structures,ACI
530-02/ASCE 5-02/TMS 402-02. Reported by the Masonry Standards Joint Committee, 2002.
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Disclaimer: Although care has been taken to ensure the enclosed information is as accurate and complete as possible, NCMA
does not assume responsibility for errors or omissions resulting from the use of this TEK.
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