Masonry walls shall be constructed in accordance with the requirements
of this section.
A. Erection precautions.
(1) Cold weather work. In cold weather, provisions shall be taken to
prevent masonry from being damaged by freezing.
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NOTE: It will be the practice to accept conformance with "Recommended
Practices for Cold Weather Masonry Construction," available from International
Masonry Institute, 823 - 15th Street, NW, Washington, D.C. 20005.
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(2) In warm weather, all clay or shale units of high absorption characteristics
shall be thoroughly wet before laying in the wall. All other masonry
units, except gypsum units laid in other than lime mortar, shall be
wetted before laying in the wall if the absorption resulting from
partial immersion in 1/8 inch of water for one minute is less than
1%.
(3) All masonry construction shall be adequately braced and supported
to insure its stability during construction.
B. Masonry units. All masonry units shall be free from physical defects
which interfere with laying of the unit and impair the compressive
strength of the unit.
C. Types of mortar. The type masonry mortar to be used for various kinds
of masonry work shall be determined from Table 756-23A. The mortar
shall be mixed in accordance with the proportions specified in Table
756-23B.
(1) Surface bond mortars. Surface bond mortars for masonry walls shall
be mixed in accordance with the proportions specified on the bag.
D. Mortar components. Mortar components shall comply with the following
requirements:
(1) Water. Water shall be clean and free of deleterious amounts of acids,
alkalies or organic materials.
(2) Admixtures or mortar colors. Admixtures or mortar colors shall not
be added to the mortar unless the resulting mortar conforms to the
requirements of the mortar specifications. Only calcium chloride may
be used as an accelerant and shall be limited to 2% by weight of the
cement used. Calcium chloride may not be used for any other purpose.
Only mineral oxide may be used as mortar color and shall not exceed
10% by weight of the cement used.
(3) Mixing. Mortar shall be mixed for at least three minutes after all
ingredients have been added with the maximum amount of water to produce
a workable consistency. Mortars that have stiffened due to water evaporation
shall be retempered by adding water as frequently as needed to restore
the required consistency. Mortars shall be used and placed in final
position within 2 1/2 hours after mixing.
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NOTE: To ensure proper mortar mixing, machine mixing is recommended.
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Table 756-23A
Types of Mortar for Various Kinds of Masonry
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Kind of Masonry
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Types of Mortar
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Foundations
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Footings
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M, S
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Walls of solid units
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M, S, N
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Walls of hollow units
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M, S
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Hollow walls
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M, S
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Masonry other than foundation masonry
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|
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Piers of solid masonry
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M, S, N
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Piers of hollow units
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M, S
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Walls of solid masonry
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M, S, N, O
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Walls of solid masonry, not less than 12 inches thick or more
than 35 feet in height, supported laterally at intervals not exceeding
12 times the wall thickness
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M, S, N, O
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Walls of hollow units; load-bearing or exterior and hollow walls
12 inches or more in thickness
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M, S, N
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Hollow walls, less than 12 inches thick
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M, S, N
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Linings of existing masonry, either above or below grade
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M, S
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Masonry other than above
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M, S, N
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Table 756-23B
Mortar Specifications by Proportion1
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Parts by Volume
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Mortar Type, ASTM C 270
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Portland Cement
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Masonry Cement
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Hydrated Lime
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Sand, Damp Loose Volume
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M
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1
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—
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1/4
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Not less than 2 1/4 and not more than 3 times the sum of
the volumes of the cements and lime
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1
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1 (Type II)
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—
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1
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—
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1/4 to 1/2
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S
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1/2
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1 (Type II)
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—
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1
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—
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1/2 to 1 1/4
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N2
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—
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1 (Type II)
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—
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NOTES:
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1
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All cements are one cubic foot per sack; lime equals 1 1/4 cubic
feet per sack.
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2
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Limited to walls with a maximum depth of five feet below grade.
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(4) Cementitious material. Cementitious material shall conform to the
standards approved by the Department.
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NOTE: The Department will accept cementitious material conforming
to the following standards: ASTM C91, Masonry Cement; ASTM C150, Portland
Cement; ASTM C595, Portland Blast-Furnace Slag Cement; ASTM C207,
Hydrated Lime for Masonry Purposes; and ASTM C5, Quick Lime for Structural
Purposes.
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(5) Aggregates. Aggregates for use in masonry mortar shall consist of
natural sand or manufactured sand and shall be graded.
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NOTE: The Department will accept aggregates in accordance with
ASTM C144.
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E. Cavity wall.
(1) Corbeling. Cavity wall construction may be supported on an eight-inch
foundation wall, provided the eight-inch wall is corbeled with solid
masonry to the width of the cavity wall. Individual corbels shall
not exceed two inches nor more than 1/3 the height of each corbeled
unit.
(2) Projections. The projection of a wall beyond the edge of a supporting
member, other than masonry such as a shelf angle or edge of a beam,
shall not exceed 1 1/4 inches, unless at least 2/3 the mass of the
wythe of masonry involved is located directly over the load-carrying
member.
F. Openings and lintels.
(1) Openings. The masonry above openings shall be supported. The bearing
length of structural elements which support the masonry above the
opening shall be not less than four inches.
(2) Lintels. Unless designed through structural analysis, lintels shall
be provided in accordance with Table 756-23C.
G. Masonry veneers.
(1) Veneer over frame construction.
(a)
Masonry veneers may be corbeled over the foundation wall, but
the corbeling shall not exceed one inch.
(b)
An air space shall be provided between the veneer and the sheathing.
(c)
Where no brick ledge is formed in the foundation wall, a thirty-pound
asphalt-saturated felt or corrosion-resistant metal base flashing
shall extend over the top of the foundation wall from the outside
face of the wall and shall extend at least six inches up on the wood
sheathing under the building paper or water-resistant sheathing.
(2) Veneer over masonry backup. A thirty-pound asphalt-saturated felt
or corrosion-resistant metal base flashing at the bottom of the veneer
shall extend over the top of the foundation and up at least six inches
and be embedded in the backup course.
H. Veneer anchorage. All veneers, supports and attachments shall be
mechanically or adhesively anchored.
(1) Mechanical anchorage. All anchors shall be corrosion-resistant.
(a)
Conventional size veneer (one square foot or less) shall be
securely attached to its backing by anchors, the equivalent of No.
22 U.S. gauge corrugated sheet steel 7/8 inch wide with at least one
such tie located in every two square feet of wall. Ties shall be embedded
two inches in a masonry joint and nailed to the framing with an 8d
nail.
(b)
Larger size veneer (greater than one square foot) shall be securely
attached with anchors, the equivalent of not less than 1/4 inch diameter
bolts in accordance with either of the following:
[1]
Each unit individually anchored to the supporting framework
with at least three anchors.
[2]
Individual units doweled to each other at all horizontal and
vertical joints so that one anchor is provided for every six square
feet of wall surface.
(2) Adhesive anchorage. Veneer may be cemented to a masonry or concrete
wall or to exterior portland cement plaster in high rib galvanized
metal lath with an adhesive, provided that the bond is sufficient
to withstand a shearing stress of 50 psi after curing for 28 days.
I. Bearing.
(1) Concentrated loads. Beams, girders, trusses, joists and other members
producing concentrated loads shall bear a minimum of three inches
on one of the following:
(a)
Concrete beam. The equivalent of a nominally reinforced 2,500
psi concrete beam, eight inches in height.
(b)
Solid masonry. At least eight inches in height of masonry composed
of solid masonry units with all voids and joints completely filled
with mortar.
(c)
Metal plate. A metal plate of sufficient thickness and size
to distribute the load to masonry units. For piers and columns, the
bearing plate shall not exceed 60% of the cross-sectional area of
the pier or column and the resultant reaction of all vertical and
horizontal loads shall fall within the middle third of the member.
(d)
Bond beam. The bond beam shall be equivalent of not less than
an eight-inch lintel (bond beam) block with two No. 4 bars embedded
in high-strength mortar fill or equivalent. The loads shall bear on
the fill.
(2) Continuous loads. Joists, trusses and beams, other than wood, spaced
four feet or more on center and 40 feet in length, slabs or other
members causing continuous loads shall be transmitted to masonry with
a minimum bearing of three inches upon solid masonry at least 2 1/2
inches in height, or as indicated for concentrated loads.
(3) Stack bond walls. Concentrated loads shall be distributed into masonry laid in stack bond by a concrete beam or bond beam [as defined in Subsection
I(1)]. For masonry of solid units, two additional rows of a continuous tie assembly may be used instead of a concrete beam or bond beam.
(4) Support of wood floor members. Where a wood structural member is
buried in masonry for support, it shall be firecut or a self-releasing
device shall be used. Where the end of a wood structural member is
built into an exterior wall, a one-half-inch air space shall be provided
at the sides, top and end of such member.
J. Bonding. Unless designed through structural analysis, all masonry
walls shall be bonded as follows:
(1) Single-wythe walls. Masonry units in single-wythe walls shall be
lapped at least two inches or 1/3 the height of the masonry unit,
whichever is greater, or through the use of continuous tie assemblies
spaced at sixteen-inch vertical intervals.
(2) Multi-wythe walls. Adjacent wythes shall be bonded with continuous
tie assemblies spaced at vertical intervals not exceeding 16 inches;
or individual ties of at least 3/16 inch diameter for each 4 1/2 square
feet of wall area, spaced at a maximum vertical distance of 18 inches
and a maximum horizontal distance of 36 inches; or bonded with a full
course of masonry headers every seventh course. The clear distance
between bond courses shall not exceed 16 inches for solid masonry
units and 24 inches for hollow masonry units. Hollow walls shall not
be bonded with headers.
K. Bolts and anchors. The allowable shear on steel bolts and anchors
shall not exceed the values given in Table 756-23D.
L. Joints.
(1) The maximum thickness of a mortar joint shall be 1/2 inch.
(2) Except for head joints used for weepholes and ventilation, solid
masonry units shall be laid to achieve full head and bed joints.
(3) Hollow masonry units shall be laid with full head joints and full
bearing areas of the face shells and under webs where the adjacent
cells are to be filled with grout.
M. Cleaning. Chemical cleaning agents shall be prevented from harming
the metal reinforcement of structural components and shall not be
of a strength which will adversely affect the mortar.
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Table 756-23C
Allowable Spans for Lintels Supporting Masonry Veneer
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Size of Steel Angle1,3
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No Story Above
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1 Story Above
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2 Stories Above
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Number if 1/2" or Equivalent Reinforcing Bars2
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L 3 x 3 x 1/4
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6' 0"
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3' 6"
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3' 0"
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1
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L 4 x 3 x 1/4
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8' 0"
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5' 0"
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3' 0"
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1
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L 6 x 3 1/2 x 1/4
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14' 0"
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8' 0"
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3' 6"
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2
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2 - L 6 x 3 1/4 x 1/4
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20' 0"
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11' 0"
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5' 0"
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4
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NOTES:
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1
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Long leg of the angle shall be placed in a vertical position.
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2
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Depth of reinforced lintels shall be not less than eight inches
and all cells of hollow masonry lintels shall be grouted solid. Reinforcing
bars shall extend not less than eight inches into the support.
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3
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Steel members indicated are adequate typical examples; other
steel members meeting structural design requirements may be used.
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Table 756-23D
Allowable Shear on Bolts and Anchors
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Bolt or Anchor Diameter
(inches)
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Embedment1
(inches)
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Allowable Shear
(pounds)
|
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1/4
|
4
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270
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3/8
|
4
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410
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1/2
|
4
|
550
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5/8
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4
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750
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3/4
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5
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1,100
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7/8
|
6
|
1,500
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|
1
|
7
|
1,850
|
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1 1/8
|
8
|
2,250
|
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NOTES:
|
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|
1
|
Bolts and anchors shall be solidly embedded in mortar or grout.
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The design and construction of structures in concrete of cast-in-place
or precast construction, plain, reinforced or prestressed, shall conform
to the rules and principles of the following standards:
A. ACI Std. 318, Building Code Requirements for Reinforced Concrete.
B. ACI Std. 512, Recommended Practice for Manufactured and Reinforced
Concrete Floor and Roof Units.
C. ACI Std. 525, Minimum Requirements for Thin Section Precast Concrete
Construction.