A.
Building brick. By building brick is meant a structural unit of burned
clay or shale, sand, lime or concrete.
(1)
All building brick shall be free from cracks, laminations or other
defects which may interfere with proper laying of the brick or impair
the strength or permanence of the structure.
(2)
Concrete building brick shall be manufactured from a mixture of Portland
cement and approved aggregates, such as sand, gravel, crushed stone,
bituminous or anthracite cinders, burned clay or shale, or blast furnace
slag.
(3)
All building brick shall be a distinctive design or appearance or
marked so that the identity of the manufacturer may be known at any
time.
B.
Hollow building units.
(1)
Hollow tile are the product of surface clay, shale, fireclay or admixtures
thereof, molded to permanent hollow form for use as masonry units
in building construction.
(2)
Hollow concrete masonry units are the products of portland cement
and suitable aggregates such as sand, gravel, crushed stone, bituminous
or anthracite cinders, burned clay or shale or blast furnace slag,
moulded to permanent hollow form for use as masonry units in building
construction.
A.
General. All basements/cellars shall be provided with a minimum of
three-inch concrete floor placed on a minimum of three inches of gravel
or equivalent. An inspection shall be called for and made prior to
laying concrete to construct the basement floor.
B.
Basementless spaces. Basementless spaces may be used or constructed
according to the following specifications:
(1)
The ground level shall be at least two feet below any part of the
wood construction.
(2)
In such spaces, all debris, sod, tree stumps and other organic materials
shall be removed and smooth surface, free of pockets, shall be provided.
A concrete slab, a minimum of two inches thick, shall be installed.
(3)
Where the floor level within the foundation walls is below the outside
grade, drain tile shall be provided around the exterior of the walls
and connected to the house drain tile.
(4)
All basementless spaces shall be provided with a minimum access opening of four square feet. If access opening is in the basement wall and is kept clear and open, except for screening which allows for air movement, this opening may be substituted for the above required ventilation area. [See § 756-15E(4).]
C.
Slab construction. The entire area shall consist of a base of three
inches in thickness of gravel or other approved material, well tamped
in place, over which there shall be placed a vapor barrier covered
with a layer consisting of four inches in thickness of concrete.
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.
|
(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
|
Types of Mortar
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|
Foundations
| |||
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Footings
|
M, S
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Walls of solid units
|
M, S, N
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Walls of hollow units
|
M, S
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|
Hollow walls
|
M, S
| ||
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Masonry other than foundation masonry
| |||
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Piers of solid masonry
|
M, S, N
| ||
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Piers of hollow units
|
M, S
| ||
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Walls of solid masonry
|
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
|
M, S, N
| ||
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Hollow walls, less than 12 inches thick
|
M, S, N
| ||
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Linings of existing masonry, either above or below grade
|
M, S
| ||
|
Masonry other than above
|
M, S, N
| ||
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Table 756-23B
Mortar Specifications by Proportion1
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|---|---|---|---|---|---|
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Parts by Volume
| |||||
|
Mortar Type, ASTM C 270
|
Portland Cement
|
Masonry Cement
|
Hydrated Lime
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Sand, Damp Loose Volume
| |
|
M
|
1
|
—
|
1/4
|
Not less than 2 1/4 and not more than 3 times the sum of
the volumes of the cements and lime
| |
|
1
|
1 (Type II)
|
—
| |||
|
1
|
—
|
1/4 to 1/2
| |||
|
S
|
1/2
|
1 (Type II)
|
—
| ||
|
1
|
—
|
1/2 to 1 1/4
| |||
|
N2
|
—
|
1 (Type II)
|
—
| ||
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NOTES:
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|---|---|---|
|
1
|
All cements are one cubic foot per sack; lime equals 1 1/4 cubic
feet per sack.
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|
2
|
Limited to walls with a maximum depth of five feet below grade.
| |
(4)
Cementitious material. Cementitious material shall conform to the
standards approved by the Department.
|
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.
|
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:
(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.
|
Table 756-23C
Allowable Spans for Lintels Supporting Masonry Veneer
| |||||
|---|---|---|---|---|---|
|
Size of Steel Angle1,3
|
No Story Above
|
1 Story Above
|
2 Stories Above
|
Number if 1/2" or Equivalent Reinforcing Bars2
| |
|
L 3 x 3 x 1/4
|
6' 0"
|
3' 6"
|
3' 0"
|
1
| |
|
L 4 x 3 x 1/4
|
8' 0"
|
5' 0"
|
3' 0"
|
1
| |
|
L 6 x 3 1/2 x 1/4
|
14' 0"
|
8' 0"
|
3' 6"
|
2
| |
|
2 - L 6 x 3 1/4 x 1/4
|
20' 0"
|
11' 0"
|
5' 0"
|
4
| |
|
NOTES:
| ||
|---|---|---|
|
1
|
Long leg of the angle shall be placed in a vertical position.
| |
|
2
|
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.
| |
|
3
|
Steel members indicated are adequate typical examples; other
steel members meeting structural design requirements may be used.
| |
|
Table 756-23D
Allowable Shear on Bolts and Anchors
| |||
|---|---|---|---|
|
Bolt or Anchor Diameter
(inches)
|
Embedment1
(inches)
|
Allowable Shear
(pounds)
| |
|
1/4
|
4
|
270
| |
|
3/8
|
4
|
410
| |
|
1/2
|
4
|
550
| |
|
5/8
|
4
|
750
| |
|
3/4
|
5
|
1,100
| |
|
7/8
|
6
|
1,500
| |
|
1
|
7
|
1,850
| |
|
1 1/8
|
8
|
2,250
| |
|
NOTES:
| ||
|---|---|---|
|
1
|
Bolts and anchors shall be solidly embedded in mortar or grout.
| |
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.
Masonry fireplaces. Masonry fireplaces shall be constructed of masonry,
stone or reinforced concrete.
(1)
Flue size. The fireplace flue size shall be based on the type of
flue and the fireplace opening indicated in Table 756-25A.
|
Table 756-25A
Minimum Flue Size for Masonry Fireplaces
| ||
|---|---|---|
|
Type of Flue
|
Minimum Cross-Sectional Area
| |
|
Round
|
1/12 of fireplace opening
| |
|
Square or rectangular
|
1/10 of fireplace opening
| |
|
Lined with firebrick
|
1/8 of fireplace opening
| |
(2)
Termination of chimney. Masonry chimneys shall extend at least three
feet above the highest point where the chimney passes through the
roof and at least two feet higher than any portion of the dwelling
within 10 feet of the chimney.
(3)
Firebox materials. The firebox shall be of the preformed metal type,
at least 1/4 inch thick, or shall be lined with firebrick, at least
two inches thick and laid in thin joints of refractory cement. The
back and sidewalls of the firebox, including the lining, shall be
at least eight inches nominally thick; at least four inches shall
be solid masonry.
(4)
Lintel. Masonry over the fireplace opening shall be supported by
a lintel of noncombustible material.
(5)
Ducts. Warm-air circulating ducts used with steel fireplace units
shall be constructed of masonry or metal.
(6)
Hearth. Fireplace hearth extensions shall be provided of approved
noncombustible material for all fireplaces. Where the fireplace opening
is less than six square feet, the hearth extension shall extend at
least 16 inches in front of and at least eight inches beyond each
side of the fireplace. Fireplace openings over six square feet shall
be provided with a hearth extension of 20 inches in front of and 12
inches beyond each side of the fireplace opening. All combustible
materials shall be kept a minimum of eight inches from the fireplace
opening.
(7)
Dampers. Dampers shall be made of cast iron or at least No 12 gauge
sheet metal. The area of the damper opening shall be at least 90%
of the required flue area when in the open position.
(8)
Hoods. Metal hoods, used as a part of a fireplace, shall be constructed
of at least No. 19 gauge corrosion-resistant metal with all seams
and connections of smokeproof construction. The hood shall be sloped
at an angle of 45° or less from the vertical and shall extend
horizontally at least six inches beyond the firebox limits. Metal
hoods shall be kept a minimum of 18 inches from the combustible materials
unless approved for reduced clearances.
|
NOTE: The Department will accept dampers and hoods listed by
nationally recognized laboratories.
|
(9)
Flue liners. Masonry chimneys shall be provided with fireclay flue
liners of at least 5/8 inch thickness. The thickness of the masonry
chimney wall shall be at least four inches. Flue liners shall be laid
in a full mortar bed of refractory cement. If the flue liners are
separated from the exterior shell by more than four inches, each individual
flue shall be wrapped by four inches of masonry.
(10)
Cleanout openings. Fireplaces with ash dumps shall be provided
with cleanout openings at the base. Doors and frames of the opening
shall be made of ferrous materials.
(11)
Mantel shelves. Woodwork or other combustible materials shall
not be placed within six inches of the fireplace opening. Combustible
materials located within 12 inches of the fireplace opening shall
not project more than 1/8 inch for each inch distance from the opening.
(12)
Chimney caps. Precast or cast-in-place concrete caps shall have
a minimum thickness of two inches and a minimum of one-inch overhang.
A minimum of a 1/4 inch soft joint shall be used between flues and
caps and shall be caulked or sealed.
(13)
Framing around fireplaces. All wood headers, joists, beams,
rafters and studs shall be located at least two inches from the outside
face of the chimney or fireplace masonry and at least six inches from
the inside surface of the flue lining. All spaces between the framing
and the fireplace shall be firestopped with noncombustible material.
B.
Factory-built fireplaces. Factory-built fireplaces consisting of
a fire chamber assembly, one or more chimney sections, a roof assembly
and other parts shall be tested and listed by a nationally recognized
testing laboratory.
(1)
Fireplace assembly and maintenance. The fireplace assembly shall
be erected and maintained in accordance with the conditions of the
listing.
(2)
Distance from combustibles. Portions of the manufactured chimney
extending through combustible floors or roof/ceiling assemblies shall
be installed in accordance with the distances listed on the chimney
in order to prevent contact with combustible materials.
(3)
Hearth extensions. Hearth extensions of not less than three-eighths-inch
thick hollow metal, stone, tile or other approved material shall be
provided.[1]
|
NOTE: Hearth extensions should extend not less than 16 inches
in front of and at least eight inches beyond both sides of the fireplace
opening.
|
C.
Factory-built fireplace stoves. Factory-built fireplace stoves, consisting
of a freestanding chamber assembly, shall be tested and listed by
a nationally recognized testing laboratory. The assembly shall be
erected and maintained in accordance with the listing.
