Designation: C956 − 04 (Reapproved 2015)

Standard Specification for

Installation of Cast-In-Place Reinforced Gypsum Concrete1
This standard is issued under the fixed designation C956; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.

1. Scope 2.2 American Concrete Institute Standard:

1.1 This specification covers the minimum requirements for ACI 318 Building Code Requirements for Reinforced Con-
the installation of cast-in-place reinforced gypsum concrete crete4
over permanent formboard. 2.3 American Welding Society Standard:
D1.1 Structural Welding Code Steel5
1.2 The values stated in inch-pound units are to be regarded
as the standard. The values given in parentheses are for 3. Terminology
information only. 3.1 Definitions shall be in accordance with Terminology
1.3 The text of this standard references notes and footnotes C11.
which provide explanatory material. These notes and footnotes 3.2 Definitions:
(excluding those in tables and figures) shall not be considered 3.2.1 primary framing, n—structural members provided to
requirements of the standard. support the reinforced gypsum concrete roof deck assembly.
3.2.1.1 purlin, n—a secondary structural member that spans
2. Referenced Documents
the primary framing members and provides support for sub-
2.1 ASTM Standards:2 purlins.
A82/A82M Specification for Steel Wire, Plain, for Concrete 3.2.2 subpurlin, n—a steel member applied transversely to
Reinforcement (Withdrawn 2013)3 the primary framing and purlins to support the formboards and
A185/A185M Specification for Steel Welded Wire to transmit the dead and live loads from the gypsum concrete
Reinforcement, Plain, for Concrete (Withdrawn 2013)3 slab to the primary framing.
A568/A568M Specification for Steel, Sheet, Carbon,
Structural, and High-Strength, Low-Alloy, Hot-Rolled and 3.2.2.1 bulb tee, n—a subpurlin, hot-rolled formed steel,
Cold-Rolled, General Requirements for rail-shaped section.
A653/A653M Specification for Steel Sheet, Zinc-Coated 3.2.2.2 truss tee, n—a subpurlin fabricated from steel wire
(Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) and strip, tee-shaped section.
by the Hot-Dip Process 3.2.3 cross tee, n—a steel tee-shaped section used to support
C11 Terminology Relating to Gypsum and Related Building a formboard end at right angles to the subpurlins where a
Materials and Systems formboard end does not occur over the purlin or primary
C317/C317M Specification for Gypsum Concrete framing.
C726 Specification for Mineral Wool Roof Insulation Board 3.2.4 formboard, n—sheet material used as a permanent
E72 Test Methods of Conducting Strength Tests of Panels form to support the gypsum concrete.
for Building Construction
3.2.5 reinforcement, n—steel wire mesh or fabric used
within the gypsum concrete slab to provide longitudinal and
transverse strength.
1
This specification is under the jurisdiction of ASTM Committee C11 on
Gypsum and Related Building Materials and Systems and is the direct responsibility 3.2.6 double-pouring, n—the application of gypsum con-
of Subcommittee C11.03 on Specifications for the Application of Gypsum and Other crete in more than one layer to complete the full slab thickness.
Products in Assemblies. See 8.7.4.3.
Current edition approved Oct. 1, 2015. Published October 2015. Originally
approved in 1981. Last previous edition approved in 2010 as C956 – 04 (2010). 3.2.7 ribbon-pouring or strip-pouring, n—the application of
DOI: 10.1520/C0956-04R15. narrow ribbons of gypsum concrete, about 10 to 12 in. (254 to
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4
Standards volume information, refer to the standard’s Document Summary page on Available from American Concrete Institute (ACI), P.O. Box 9094, Farmington
the ASTM website. Hills, MI 48333-9094, http://www.concrete.org.
3 5
The last approved version of this historical standard is referenced on Available from American Welding Society (AWS), 550 NW LeJeune Rd.,
www.astm.org. Miami, FL 33126, http://www.aws.org.

Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States

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 C956 − 04 (2015)
305 mm) wide by 1 to 11⁄2 in. (25.4 to 38.1 mm) deep, across 7.4 Reinforcement, Specification A82/A82M, shall be fab-
the width of the formboard at center of span between purlins. ricated from zinc-coated (galvanized) welded or woven steel
wire mesh or fabric having an effective cross-sectional area of
4. Delivery of Materials not less than 0.026 in. 2 (16.77 mm)2 per foot of slab width.
4.1 Materials shall be delivered in original packages, Reinforcement shall be free of rust, scale, or other materials
containers, or bundles bearing the brand name and name of that reduce bond to the gypsum concrete.
producer or seller. Bulk materials shall be delivered with the 7.4.1 Hexagonal Reinforcing Mesh, shall be fabricated from
brand name and name of the producer or seller shown on the 2 in. (50.8 mm) hexagonal mesh formed of not less than 0.0410
accompanying bills of lading. in. (1.04 mm) diameter wires with longitudinal wires not less
than 0.0625 in. (1.59 mm) in diameter, spaced not more than 3
5. Storage of Materials in. (76.2 mm) on centers. Steel wire for fabricating wire mesh
5.1 All materials shall be stored in a manner that prevents and fabric—Specification A82/A82M.
damage before use. When stored under tarpaulins, ventilation 7.4.2 Rectangular Reinforcing Fabric, Specification A185/
shall be provided to prevent moisture accumulation under the A185M, shall be fabricated from longitudinal wires not less
tarpaulin. than 0.1055 in. (2.68 mm) in diameter spaced not more than 4
5.2 Formboard shall be stored flat and off the ground. in. (102 mm) on centers and transverse wires not less than
Handling and stacking shall be done in such a manner to 0.0800 in. (2.03 mm) in diameter spaced not more than 8 in.
prevent damage to face, ends, and edges and keep dry until use. (203 mm) on centers.
5.3 When it is necessary to store gypsum concrete at the job 7.5 Gypsum Concrete, Specification C317/C317M, Class A.
site, the gypsum concrete shall be stored off the ground and 7.6 Water, shall be potable and free of substances that could
kept dry until use. adversely affect the gypsum concrete.
6. Environmental Conditions 7.7 Expansion Filler Strip, shall be not less than 3⁄4 in. (19
mm) thick and equal in height to the abutting gypsum concrete
6.1 The minimum temperature at which gypsum concrete is
and of the type specified by the producer of the gypsum
mixed and placed is not specified. Gypsum concrete shall not
concrete.
be mixed with water containing ice crystals.
NOTE 1—An exothermic reaction during setting ensures complete 8. Installation
hydration before freezing.
8.1 Installation of Subpurlins:
7. Materials 8.1.1 Installation, Normal:
7.1 Subpurlins: 8.1.1.1 Subpurlins—The subpurlins shall be placed trans-
7.1.1 Subpurlins shall be designed to support live and dead versely to the purlins and primary framing and shall be spaced
loads of the roof deck. to suit the size of the formboards specified. Subpurlins shall be
7.1.2 Hot-rolled and cold-rolled steel shapes other than bulb of sufficient length so that their joints occur over purlins or
tees or truss tees shall meet the requirements of this specifica- primary framing. Subpurlin joints shall be alternated so that the
tion for subpurlins. joints are staggered one purlin space.
7.2 Cross Tees, shall be not less than 11⁄4 in. (31.75 mm) 8.1.1.2 Subpurlins shall be welded to purlins and steel
wide by 1⁄2 in. (12.7 mm) high, fabricated from not less than 26 primary framing with 1⁄8 in. (3.2 mm) fillet welds not less than
1⁄2 in. (12.7 mm) long on alternate sides of the subpurlin at each
gage zinc-coated steel conforming to Specifications A653/
A653M or A568/A568M. intersection with purlins. Except as otherwise specified, weld-
ing shall be in accordance with AWS D1.1. Where primary
7.3 Formboard: framing is of wood, nails not less than 16d shall be used on
7.3.1 Mineral Fiber Formboard, Specification C726, not each side of the subpurlins at each intersection. The nails shall
less than 3⁄4 in. (19.0 mm) thick nor more than 3 in. (76 mm) be bent over approximately 3⁄4 in. (19 mm) to securely clinch
thick. It shall sustain a uniform load of 20 lb/ft2 (97 kg/m2). the flange of the subpurlin.
7.3.1.1 Mineral fiber formboard shall be tested in accor- 8.1.2 Installation Seismic:
dance with the transverse loading test of Test Methods E72.
8.1.2.1 Subpurlins—The subpurlins shall be welded at each
7.3.1.2 The test specimen shall be uniformly loaded and
intersection with the purlins with 1⁄8-in. (3.2-mm) fillet welds
supported at both edges and ends. The test specimens shall be
not less than 1 in. (25.4 mm) long, on one side. Both sides of
supported at the perimeter with a frame providing 1 in. (25.4
the subpurlin shall be welded with 1⁄8-in. fillet welds not less
mm) bearing on ends and 1⁄2 in. (12.7 mm) bearing on edges
than 2 in. (50.8 mm) long where subpurlin joints occur over the
and 7 in. (177.8 mm) nominal clearance from the bed of the
purlin. Both sides of the subpurlin shall be welded with 1⁄8-in.
apparatus.
fillet welds not less than 2 in. long at shear transfer points and
7.3.1.3 For formboards 3⁄4 in. (19.0 mm) thick, test speci-
at intersections with exterior frame.
mens shall be 48 in. (1200 mm) long by 24 in. (600 mm) wide.
7.3.1.4 For formboards 1 in. (25.4 mm) thick or greater, test 8.1.3 Maximum Spans—Refer to X2.1.3.
specimens shall be 48 in. (1200 mm) long by 32 in. (800 mm) 8.2 Cross Tees—Cross tees shall be provided where form-
wide. board ends are supported by purlins or the primary framing.

2
 C956 − 04 (2015)
8.3 Formboards—Formboards shall be located face down 8.7.4 Placement:
on the flanges of the supporting members and with the ends on 8.7.4.1 General—To avoid exposure to inclement weather
top of the purlins. and physical abuse, gypsum concrete shall be placed the same
8.3.1 Gypsum concrete shall not be poured over formboards day as the installation of the formboard and reinforcement
which have been wetted by rain or snow. materials.
8.3.2 The gypsum concrete shall be poured on the same day (a) The deck shall be poured in sections of similar size.
the formboards are installed. 8.7.4.2 Screeds Grounds—Screeds, such as metal bars or
8.4 Reinforcement—The mesh of wire fabric shall be lo- wood strips, shall be spaced approximately 10 ft (3050 mm)
cated with the main longitudinal wires at right angles to the apart at right angles on top of the subpurlins at a height that
subpurlins and adjacent to the formboard at midspan between will allow the gypsum concrete slurry to be leveled at the
the purlins. Ends of the reinforcement shall be lapped not less specified thickness.
than 4 in. (102 mm) or one mesh, whichever is greater. (a) Gypsum concrete cants, curbs, and drainage slopes shall
be placed to the design thickness. Curbs around openings shall
8.4.1 Edges shall be butted, not lapped, unless required for
be permitted to be formed with the formboard.
fire rated or horizontal diaphragm construction. Reinforcement
8.7.4.3 The gypsum concrete shall be discharged into place-
shall be cut to fit at walls, curbs, and openings, folded over on
ment equipment immediately after completion of mixing.
to itself, and extended into all areas when gypsum concrete is
(a) The slurry shall be poured or discharged not more than
to be placed.
24 in. (600 mm) off the formboard to minimize impact and
8.5 Expansion Filler Strips—Expansion filler strips shall be allowed to build to full thickness in one continuous operation.
placed continuously against the walls, curbs, nailers, or other Double pouring shall not be permitted.
rigid surfaces that gypsum concrete will abut. (b) As soon as the slurry has stiffened enough to hold a full
8.6 Expansion Joints—Expansion joints shall be located at level, it shall be screeded to a true, even surface using a
expansion joints found in the main structure, at a maximum of smooth, rigid straight-edge.
200 ft (61 m) on center in a direction parallel to the subpurlins 8.7.4.4 Place gypsum concrete cants, curbs, and drainage
on large buildings, at intersections of wings on L-, U-, T-, and slopes to the design thickness. Curbs around openings shall be
H-shaped buildings and, wherever the roof framing changes permitted to be formed with the formboard.
direction. See X1.5.5. 8.8 Roof Overhangs—Gypsum concrete shall not be placed
8.7 Gypsum Concrete Mixing and Placement: on roof overhangs, eaves, or other similar locations, on
8.7.1 General—All equipment, including mixers, pumps, formboards unless the underside is protected against direct
hoses, tools, and screeds shall be kept clean and free of set wetting by a suitable facia drip cap overhang.
gypsum concrete throughout the placement operation. 8.9 Drying—Construction moisture shall be removed from
8.7.2 Proportioning—The ratio of water to gypsum concrete the building to permit drying of completed gypsum concrete
shall be that specified by the producer of the gypsum concrete; slab, providing heat and ventilation where required. See X1.3.
additional water is prohibited. Volumetric or metering devices 8.10 Protection of Completed Slab—Gypsum concrete is not
shall be used to ensure accurate measurement. a finished traffic or weather protective surface. The top side of
8.7.3 Mixing—Mixing shall be thorough but not overmixed. the completed gypsum concrete slab shall be protected with a
The slurry shall be discharged into placement equipment permanent waterproof covering.
immediately after completion of mixing to avoid buildup of set
material. 9. Keywords
8.7.3.1 Calcium chloride or other admixtures shall not be 9.1 calculation of diaphragm shear; gypsum concrete; gyp-
added to the gypsum concrete. sum roof deck

APPENDIXES

(Nonmandatory Information)

X1. GENERAL INFORMATION

X1.1 Limitations of Use X1.1.2 Moisture Exposure—Cast-in-place gypsum concrete

X1.1.1 Roof Shapes and Designs—Gypsum roof decks is not recommended for general use in occupancies where it
meeting this specification can be installed on flat, warped, may be exposed to sustained relative humidity greater than
sawtooth, curved, or pitched roofs. 90 % or condensing moisture. The producer of the gypsum
concrete should be consulted regarding limitations of use in
NOTE X1.1—On flat roofs, a minimum pitch of 1⁄8 in./ft (10.4 mm/m) is
recommended.
high humidity occupancies.

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 C956 − 04 (2015)
X1.1.3 Temperature Exposures—Where intermittent or ex- X1.5 Roof Coverings
tended exposures to high temperatures are to be expected, such X1.5.1 Built-up or other suitable roof coverings should be
as in slabs directly exposed to radiant heat over furnace specified over poured gypsum concrete roof slabs.
breachings, the gypsum concrete producer should be consulted
for specific recommendations. X1.5.2 The application of metal or other rigid types of roof
covering over poured gypsum concrete decks is not generally
X1.1.4 Acid Fumes—If acid fumes are to be encountered, recommended. If sheet metal roof coverings are required over
the producer of the gypsum concrete should be consulted for portions of a poured gypsum concrete deck, their anchoring
his specific recommendations. members must be attached either by the use of toggle bolts
X1.1.5 Surface Protection—Gypsum concrete decks shall passing entirely through the slab and formboards or by suitable
not be used as a finished surface to bear traffic or other loads. fastening to the primary members. Where shingle-type roof
Protective permanent waterproof coverings shall be installed as coverings are contemplated, the gypsum concrete producer’s
soon as possible after completion of the slab. recommendations for attachment should be followed.
X1.1.6 Welding Precautions—Except as modified in the X1.5.3 Provisions for furnishing and installing roof sumps
body of this specification, welding shall be in accordance with should be included in other sections of the specification.
AWS D1.1. Welding will not be permitted when the tempera- X1.5.4 The application of roof covering should follow as
ture is lower than 0°F (−18°C), when steel surfaces are wet, or promptly after the placing of gypsum concrete as possible. The
under other conditions not recommended by the American top surface of the slab should be reasonably hard as indicated
Welding Society. by the disappearance of visible moisture gloss from its surface.
X1.2 Support for Suspended Ceilings X1.5.5 Expansion joints should be installed in the roofing
wherever they are provided in the gypsum concrete and the
X1.2.1 Suspended ceilings should be hung from the primary
main structure.
framing. Ceilings may be hung from the subpurlins. A design
check shall be made in accordance with applicable building X1.6 Painting Undersides of Gypsum Concrete Roof
codes and regulations to verify that the structural adequacy of Decks
the subpurlins and the added weight of the ceiling will not
X1.6.1 The underside of the gypsum deck is usually not
cause the subpurlins to deflect more than that allowed by the
further decorated. If painting is desired, it should be deferred
roof deck or ceiling sign or that allowed by subpurlin design.
until the formboard and the slab are thoroughly dry through
Hangers should not be fastened into or through the gypsum
their total thickness.
concrete slab or the formboards. Similar precautions should be
followed for the suspension of unit heaters, light troffers, and X1.7 Framing Requirements
piping.
X1.7.1 The primary framing to receive subpurlins and the
X1.3 Drying of Slabs primary framing spaced to directly receive the formboards for
the gypsum concrete are not part of the gypsum concrete
X1.3.1 Subsequent to the placing of gypsum concrete, specifications. However, it is essential that the following
ventilation accompanied by heat is recommended below the provisions regarding such framing be incorporated in other
slabs to remove the excess construction moisture resulting sections.
from the slab pouring, placement of concrete floors, masonry X1.7.1.1 Spacing of primary structural supports to receive
plastering, and other similar construction work. Where natural the subpurlins of the reinforced gypsum concrete assembly
ventilation is inadequate, mechanical ventilation is required to must be such that design stresses in the specified subpurlins are
remove construction moisture from the building. When sus- not exceeded.
pended ceilings are installed below the slabs, provisions should X1.7.1.2 When subpurlins are not used, the following pro-
be made to permanently vent the enclosed space below the visions should be made to anchor the slab to the primary
deck, particularly that space above a suspended ceiling, using framing members to resist uplift forces and movements due to
sufficient gravity or mechanical ventilation to remove all temperature changes.
construction moisture and excessive moisture vapor resulting X1.7.1.2.1 Weld steel tee sections sized from 1 by 1 by 1⁄8
from subsequent occupancy. in. (25.4 by 25.4 by 3.2 mm) to 11⁄2 by 11⁄2 by 3⁄16 in. (38.1 by
38.1 by 4.7 mm) across the joists at approximately 32 in.
X1.4 Provisions for Expansion and Contraction (812.8 mm) to 48 in. (1219 mm) on center depending on type
X1.4.1 Provision for relief of expansion and contraction of formboard used. The reinforcing mat must then be wire tied
should be considered for all cast-in-place roof decks. Wherever to these tee sections.
expansion joints have been provided in the main structure, they X1.7.1.2.2 Wiring of formboard to the frame as a means of
must also be provided in the roof deck and roof covering. The providing uplift resistance is not permissible.
use of suitable expansion strips at the junction between roof X1.7.1.3 Heavy concentrated loads, such as water tanks,
slabs and parapets is recommended for further relief of large fan bases, cooling towers, and flag poles, must not be
expansion and contraction stresses in the slabs. Where subpur- imposed directly on the poured gypsum concrete roof deck.
lins are used, edge expansion strips need be used only at walls Details must provide for transmitting such loads directly to the
where subpurlins abut walls at right angles. walls, primary framing or structural supports.

4
 C956 − 04 (2015)
X1.7.1.4 The architect or engineer should assign by speci- X1.8.3 Reinforcement should have main longitudinal
fication the responsibility for furnishing and installing of roof strands laid at right angles to subpurlins and near formboard at
nailers and for framing at openings and expansion joints, eaves midspan.
and wall angles, and similar special items. X1.8.3.1 Edges should be butted. Edges should not be
X1.7.1.5 It is important that the gypsum concrete roof deck lapped unless required for fire rated or horizontal diaphragm
be designed with sufficient slope to provide adequate drainage construction.
and eliminate the possibility of free-standing water.
X1.8.3.2 Ends should be lapped a minimum of 4 in. (101.6
X1.8 Evaluation and Inspection mm). At slab edges, the fabric should be folded back to provide
X1.8.1 Metal framing members should be of the sizes greater bond within the slab.
specified and have a factory applied coating to prevent rust. X1.8.4 Top surface of the gypsum concrete slab should be
X1.8.1.1 Welds should meet the requirements of AWS D1.1 smooth and free of any protrusions.
and be correctly located and of the size specified.
X1.8.2 Formboards should be of the type, size, and thick-
ness specified and should be free of damage rendering them
unfit for their intended use.

X2. DESIGN

X2.1 General Q e 5 @ 0.16 f g tC1 11000 ~ k 1 d 1 1k 2 d 2 ! # C 2 C 3 (X2.1)

X2.1.1 Reinforced gypsum concrete shall be designed to Q m 5 @ 0.0000133 f g tC1 10.175 ~ k 1 d 1 1k 2 d 2 ! # C 2 C 3 (X2.2)
support the anticipated loads and to withstand the forces to
where:
which they may be subjected without exceeding the allowable
stresses specified in X2.1.1.1. Except as otherwise specified, Qe = allowable shear on diaphragm in lb per linear ft which
methods of design shall follow established principles of includes a one-third increase for short-term loading,
mechanics and principles of design for reinforced concrete in Qm = allowable shear on diaphragm in kN·m which includes
accordance with ACI 318.X2. The minimum ratio of area of a one-third increase for short-term loading,
reinforcement to area of portland cement concrete for shrink- fg = oven-dry compressive strength of gypsum in lbf/in.2
age and temperature shall not apply to gypsum concrete. (kPa) as determined by tests conforming to this
X2.1.1.1 Allowable Stresses—not more than: specification,
C1 = 1.0 for Class A gypsum concrete,
Compressive stress in bending 0.25 fg (Note X2.1) t = thickness of gypsum concrete between subpurlins in
Axial compressive or bearing stress 0.20 fg (Note X2.1)
Bond stress (plain reinforced bars) 0.02 fg (Notes X2.1 and X2.2) inches (mm). For the purpose of computing diaphragm
Bond stress (for deformed reinforced 0.03 fg (Note X2.1) shear values, t shall be not more than 4 in. (101.6 mm),
bars or electrically welded mesh)
Shear stress 0.02 fg (Notes X2.1 and X2.2) k1 = number of mesh wires per ft (wires per m) passing
NOTE X2.1—fg indicates the compressive strength of the gypsum over subpurlins,
concrete as determined in accordance with the requirements of Specifi- d1 = diameter of mesh wires passing over subpurlins in
cation C317/C317M, Class A. inches (mm) except hexagonal mesh,
NOTE X2.2—Gypsum concrete meets the bond and shear requirements k2 = number of mesh wires per foot (wires per metre)
of this section when reinforced with steel wire reinforcement conforming
to the requirements of 7.4. parallel to subpurlins or 0.7 times the number of
hexagonal wires,
X2.1.2 Minimum Thickness—Not less than 2 in. (50.8 mm) d2 = diameter in inches of mesh wires parallel to subpurlins
measured at all points over the top surface of the formboard. or of hexagonal wires,
X2.1.3 Maximum Spans—Not more than 31 in. (787 mm) C2 = 1.4 for Class A gypsum concrete using the truss tee
between supports when using subpurlins and formboards. and 1.0 for bulb tee, and
X2.1.4 Maximum Spacing of Supports—Not more than 36 C3 = 0.85 for perlited gypsum concrete, 1.0 for gypsum
in. (914 mm) for gypsum concrete slabs over formboards concrete made with wood chips or wood shavings.
applied directly to primary framing members. The allowable shear values are shown in Tables X2.1 and
X2.2.
X2.2 Seismic and Wind Conditions—Where the gypsum
concrete roof deck is used as a horizontal diaphragm to NOTE X2.3—k1 = X2.5 for 2 in. (50.8 mm) hexagonal mesh woven of
transmit seismic or wind loads, the subpurlins shall be installed No. 19 gage galvanized wire with additional longitudinal No. 16 gage
in accordance with 9.1.2. galvanized wires spaced every 3 in. (75.8 mm) across the width of the
mesh.
X2.2.1 Diaphragm Shear—Determine shear in poured gyp-
sum concrete diaphragms as follows:

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 C956 − 04 (2015)
TABLE X2.1 Allowable Shear Values in Pounds per Foot Using Truss or Bulb Tee SubpurlinsA
Perlited Gypsum Concrete—Class A (500 psi)
Truss Tee Subpurlins, Mesh Type Bulb Tee Subpurlins, Mesh Type
Concrete Thickness, Galvanized Galvanized
in. 4×8 6×6 Hexagonal 4×8 6×6 Hexagonal
#12 × #14 #10 × #10 #12 × #14 #10 × #10
2 718 831 878 513 593 627
2.5 765 878 926 547 627 661
3 813 926 974 581 661 695
3.5 860 973 1021 615 695 729
4 908 1021 1069 649 729 763
Wood Chips or Wood Shavings Gypsum Concrete—Class A (500 psi)
Truss Tee Subpurlins, Mesh Type Bulb Tee Subpurlins, Mesh Type
Concrete Galvanized Galvanized
Shear ValuesB
Thickness, in. 4×8 6×6 Hexagonal 4×8 6×6 Hexagonal
#12 × #14 #10 × #10 #12 × #14 #10 × #10
2 844 977 1033 603 698 738 840
2.5 900 1033 1089 643 738 778
3 956 1089 1145 683 778 818
3.5 1012 1145 1201 723 818 858
4 1068 1201 1257 763 858 898
A
The tabulated shear values are for short-term loads due to wind or earthquake forces and are not permitted a one-third increase for duration of load.
B
Recommended shear transfer provided such truss tees are embedded not less than 3⁄8 in. (9.5 mm) deep in gypsum concrete and are welded to the structural frame
with not less than 1⁄8 in. (3.2 mm) fillet welds not less than 11⁄2 in. (38.1 mm) long at 6 in. (152.4 mm) on centers both sides bottom flanges and the mesh is tied to top
flange of such subpurlins.

TABLE X2.2 Allowable Shear Values in kiloNewtons per Meter Using Truss or Bulb Tee Subpurlins (Metric)A
Perlited Gypsum Concrete—Class A (3450 kPa)
Truss Tee Subpurlins, Mesh Type Bulb Tee Subpurlins, Mesh Type
Concrete Thickness,
mm 4×8 6×6 4×8 6×6
Hexagonal Hexagonal
#12 × #14 #10 × #10 #12 × #14 #10 × #10
50.8 10.5 12.1 12.8 7.47 8.65 9.15
63.5 11.2 12.8 13.5 7.97 9.15 9.64
76.2 11.8 13.5 14.2 8.46 9.64 10.1
88.9 12.5 14.2 14.9 8.96 10.1 10.6
101.6 13.2 14.9 15.6 9.45 10.6 11.1
Wood Chips or Wood Shavings Gypsum Concrete—Class A (3450 kPa)
Truss Tee Subpurlins, Mesh Type BulbTeeSubpurlins,MeshType
Concrete
4×8 6×6 4×8 6×6 Shear ValuesB
Thickness, mm Hexagonal Hexagonal
#12 × #14 #10 × #10 #12 × #14 #10 × #10
50.8 12.3 14.2 15.1 8.79 10.2 10.8 12.3
63.5 13.1 15.1 15.9 9.37 10.8 11.3
76.2 13.9 15.9 16.7 9.96 11.3 11.9
88.9 14.8 16.7 17.5 10.5 11.9 12.5
101.6 15.6 17.5 18.3 11.1 12.5 13.1
A
The tabulated shear values are for short-term loads due to wind or earthquake forces and are not permitted a one-third increase for duration of load.
B
Recommended shear transfer provided such truss tees are embedded not less than 9.5 mm (3⁄8 in.) deep in gypsum concrete and are welded to the structural frame
with not less than 3.2 mm (1⁄8 in.) fillet welds not less than 38.1 mm (11⁄2 in.) long at 152.4 mm (6 in.) on centers both sides bottom flanges and the mesh is tied to top
flange of such subpurlins.

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