ASTM C635-00
(Specification)Standard Specification for the Manufacture, Performance, and Testing of Metal Suspension Systems for Acoustical Tile and Lay-in Panel Ceilings
Standard Specification for the Manufacture, Performance, and Testing of Metal Suspension Systems for Acoustical Tile and Lay-in Panel Ceilings
SCOPE
1.1 This specification covers metal ceiling suspension systems used primarily to support acoustical tile or acoustical lay-in panels.
1.2 Some suspension systems incorporate locking assembly details that enhance performance by providing some continuity or load transfer capability between adjacent sections of the ceiling grid. The test methods included in this specification do not provide the means for making a complete evaluation of continuous beam systems, nor for assessing the continuity contribution to overall system performance. However, the test methods can be used for evaluating primary structural members in conjunction with secondary members that interlock, as well as with those of noninterlocking type.
1.3 While this specification is applicable to the exterior installation of metal suspension systems, the atmospheric conditions and wind loading require additional design attention to ensure safe implementation. For that reason, a specific review and approval should be solicited from the responsible architect and engineer, or both, for any exterior application of metal suspension systems in the construction of a new building or building modification.
1.4 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are provided for information purposes only.
1.5 The following safety hazards caveat pertains only to the test methods described in this specification. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: C 635 – 00
Standard Specification for
the Manufacture, Performance, and Testing of Metal
Suspension Systems for Acoustical Tile and Lay-in Panel
Ceilings
This standard is issued under the fixed designation C 635; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 2. Referenced Documents
1.1 This specification covers metal ceiling suspension sys- 2.1 ASTM Standards:
tems used primarily to support acoustical tile or acoustical B 117 Practice for Operating Salt Spray (Fog) Apparatus
lay-in panels.
3. Terminology
1.2 Some suspension systems incorporate locking assembly
details that enhance performance by providing some continuity 3.1 Definitions:
3.1.1 Where these terms appear in this specification they
or load transfer capability between adjacent sections of the
ceiling grid. The test methods included in this specification do shall have the meaning herein indicated as follows:
3.1.1.1 backing board— a flat sheet of gypsum board to
not provide the means for making a complete evaluation of
continuous beam systems, nor for assessing the continuity which acoustical tile is attached using adhesive, screws,
staples, or other suitable means (Fig. 1c).
contribution to overall system performance. However, the test
methods can be used for evaluating primary structural mem- 3.1.1.2 bow—the maximum component of deviation in the
vertical plane of a main runner, cross runner, or wall molding
bers in conjunction with secondary members that interlock, as
well as with those of noninterlocking type. where the centroidal axis of these structural components has
been permanently deformed from end to end into the shape of
1.3 While this specification is applicable to the exterior
installation of metal suspension systems, the atmospheric a simple regular curve during the manufacturing process (Fig.
2).
conditions and wind loading require additional design attention
to ensure safe implementation. For that reason, a specific
NOTE 1—The meanings for bow and camber given here may differ from
review and approval should be solicited from the responsible
those applied elsewhere.
architect and engineer, or both, for any exterior application of
3.1.1.3 camber—the maximum component of deviation in
metal suspension systems in the construction of a new building
the horizontal plane of a main runner, cross runner, or wall
or building modification.
molding where the centroidal axis of these structural compo-
1.4 The values stated in inch-pound units are to be regarded
nents has been permanently deformed from end to end into the
as the standard. The values given in parentheses are provided
shape of a simple regular curve during the manufacturing
for information purposes only.
process (Fig. 2).
1.5 The following safety hazards caveat pertains only to the
3.1.1.4 carrying channel or hanging channel—the three-
test methods described in this specification. This standard does
sided or “[”-shaped metal sections that support the entire
not purport to address all of the safety concerns, if any,
structural grid network in some forms of mechanical ceiling
associated with its use. It is the responsibility of the user of this
suspension systems (Fig. 1b). The carrying channels are
standard to establish appropriate safety and health practices
usually suspended by hanger wires from the existing structure
and determine the applicability of regulatory limitations prior
and the main runners are then attached to the channels.
to use.
3.1.1.5 ceiling suspension system—the entire network or
grid of structural components, as defined by the ceiling
This specification is under the jurisdiction of ASTM Committee E-33 on
suspension system manufacturer, that provides support for
Environmental Acoustics and is the direct responsibility of Subcommittee E33.04 on
Application of Acoustical Materials and Systems.
Current edition approved May 10, 2000. Published August 2000. Originally
published as C 635 – 69. Last previous edition C 635 – 97. Annual Book of ASTM Standards, Vol 03.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 635
FIG. 1 Three Types of Ceiling Suspension Systems Showing All Components
acoustical ceiling tile, acoustical ceiling panels, lighting fix- 3.1.1.8 horizontal plane (of a structural component of a
tures, and air diffusers. ceiling suspension system)—a plane parallel to the plane of the
3.1.1.6 cross runner— the secondary or cross beams of a ceiling which passes through the centroidal axis of the member
mechanical ceiling suspension system (Fig. 1, a and b). The (Fig. 2).
cross runners usually support only the acoustical tile. In some 3.1.1.9 interlocking—a ceiling system where the cross run-
forms of suspension systems, however, the cross runners also ners are connected to the main runner or other cross runners, or
provide support for lighting fixtures, air diffusers, and other both, at intervals controlled by slots, holes, etc. in the main
cross runners. runners.
3.1.1.7 hanger wire— the wire employed to suspend the 3.1.1.10 main runner— the primary or main beams of the
acoustical ceiling from the existing structure (wood joists, steel type of ceiling suspension system in which the structural
bar joists, steel beams, concrete slabs, etc.) (Fig. 1). members are mechanically locked together (Fig. 1, a and b).
C 635
FIG. 2 Diagrams Showing Camber, Bow, and Twist
The main runners provide direct support for cross runners, and 3.1.1.15 vertical plane (of a structural component of a
may support lighting fixtures and air diffusers. In addition, the ceiling suspension system)—a plane perpendicular to the plane
of the ceiling which passes through the centroidal axis of the
acoustical tile may also be directly supported by the main
member (Fig. 2).
runners. In some forms of mechanical ceiling suspension
3.1.1.16 wall molding— the edge angles or channels of a
systems, the main runners are supported by hanger wires
mechanical ceiling suspension system that are attached to a
attached directly to the existing structure. In other forms, the
wall (Fig. 1, a and b). The wall molding provides support for
main runners (also referred to as “H” runners, “Z” bars, etc.)
the acoustical tile, main runners and cross runners that are
are installed perpendicular to carrying channels and are sup-
located at the periphery of the ceiling.
ported by specially designed sheet metal or wire clips attached
to the carrying channels.
4. Classification
3.1.1.11 nailing bar or furring bar—the continuous sheet
4.1 The structural performance required from a ceiling
metal strips to which a backing board is attached using either
suspension system shall be defined by the specifying authority
nails or screws (Fig. 1c). The nailing bars are installed
in terms of a suspension system structural classification.
perpendicular to and supported by the carrying channels.
4.1.1 The structural classification of ceiling suspension
3.1.1.12 non-interlocking—a ceiling system that does not
systems shall be based on the load-carrying capacity of the
comply with the specifications stated in the definition of
main runners of the structural network. Load-carrying capacity
interlocking.
as used herein is based on the more stringent requirement of
3.1.1.13 spline—a strip of metal or fiber inserted in the kerfs
esthetic acceptance rather than the less confining prevention of
of adjacent acoustical tile to form a concealed mechanical joint
structural failure. The criterion is the arbitrary but widely
seal (Fig. 1b). 1
established limit of deflection to ⁄360 of the span between
3.1.1.14 twist—the angle of rotation measured in a trans- supports.
verse plane between the two end cross sections of a main
4.1.2 The load-carrying capacity shall be the maximum
runner, cross runner, or wall molding which has been perma-
uniformly distributed load (pounds per linear foot) that a
nently deformed during the process of manufacturing (Fig. 2). simply supported main runner section having a span length of
C 635
4 ft, 0 in. (1.219 m) is capable of supporting without the shall be stated by the suspension system manufacturer in
mid-span deflection exceeding 0.133 in. (3.38 mm) or ⁄360 of published literature. The thickness in thousandths of an inch of
the 4 ft, 0 in. span length, as tested in accordance with the metal and the allowable thickness variation for the component
method described in Section 8. shall be stated.
4.1.3 The structural classification or grade of ceiling sus- 5.1.1.2 For aluminum systems the thickness of metal used in
pension systems shall be determined by the capability of main main runners, cross runners, wall moldings, or splines shall be
runners or nailing bars to support a uniformly distributed load. stated by the suspension system manufacturer in published
These classifications shall be: literature. The thickness in thousandths of an inch of metal and
4.1.3.1 Light-Duty Systems, used where ceiling loads other the allowable thickness variation for the component shall be
than acoustical tile or lay-in panels are not anticipated, such as stated.
residential and light commercial structures. 5.1.2 Straightness:
4.1.3.2 Intermediate-Duty Systems, used where ceiling 5.1.2.1 The amount of bow, camber, or twist in main
loads other than acoustical tile or lay-in panels (light fixtures, runners, cross runners, wall molding, splines, or nailing bars of
air diffusers, etc.) are anticipated, such as ordinary commercial various lengths shall not exceed the values shown in Table 2.
structures. 5.1.2.2 Main runners, cross runners, wall moldings, splines,
4.1.3.3 Heavy-Duty Systems, used where the quantities and or nailing bars of ceiling suspension systems shall not contain
weights of ceiling fixtures (lights, air diffusers, etc.) are greater local kinks or bends.
than those for an ordinary commercial structure. 5.1.3 Length:
4.1.4 For the purpose of determining the structural classifi- 5.1.3.1 The variation in the specified length of main runner
cation of main runner members as covered in 4.1.2, their sections or cross runner sections that are part of an interlocking
simple-span, minimum load-carrying capabilities, when tested grid system shall not exceed 60.010 in./4 ft (0.21 mm/m).
in accordance with the test method described in Section 10, 5.1.3.2 The variation in the specified spacing of slots or
shall be listed as shown in Table 1. other cutouts in the webs of main runners or cross runners that
4.2 Cross runners shall be capable of carrying the load are employed in assembling a ceiling suspension grid system
specified by the manufacturer without exceeding the maximum shall not exceed 60.010 in. (0.25 mm).
allowable deflection equal to ⁄360 of its span. 5.1.4 Over-all Cross-section Dimensions:
4.3 The design and definition of the suspension system shall 5.1.4.1 For steel systems, the overall height of the cross
be the responsibility of the manufacturer. Included is selection section of main runners, cross runners, wall molding, or nailing
of appropriate materials, metal thicknesses, dimensions of bar shall be the specified dimensions 60.030 in. (0.76 mm).
necessary component section configurations, design of special The width of the cross section of exposed main runners or cross
hanger and assembly devices, and provision for whatever runners shall be the specified dimension 60.008 in. (0.20 mm).
accessory items are needed to ensure satisfactory ceiling 5.1.4.2 For aluminum systems, the overall height of the
performance within the scope of this specification. cross section and the allowable variation of main runners, cross
4.3.1 System manufacturers may provide supplementary runners, or wall molding shall be stated by the suspension
data describing load deflection capabilities of main runners in system manufacturer in published literature and price lists. The
each classification for spans other than 4 ft (1.2 m). width and allowable variation of the cross section of exposed
4.4 Where specialized loading conditions that are outside main runners or cross runners shall be similarly stated.
the scope of this specification exist, the manufacturer should be 5.1.5 Section Squareness:
consulted for his recommendations; and, he may furnish 5.1.5.1 Intersecting webs and flanges of structural members
engineering data as required. Specification or design of super- (“I”,“ T”, or “Z” sections) shall form angles between them of
structure anchors or fasteners are not the responsibility of the 906 2°. If deviations from squareness at more than one such
ceiling system manufacturer unless specified by the ceiling intersection are additive with respect to their use in a ceiling,
system manufacturer as part of the suspension system. the total angle shall not be greater than 2°.
5.1.5.2 The ends of structural members that abut or intersect
5. Dimensional Tolerance
other members in exposed grid systems shall be cut perpen-
5.1 Suspension system structural members shall conform to dicular to the exposed face, 90° + 0, − 2°.
5.2 Suspension system assembly devices shall satisfy the
the following tolerance requirements:
5.1.1 Metal Thickness: following requirements and tolerances.
5.2.1 The design of and dimensional tolerances set by the
5.1.1.1 For steel systems the thickness of metal used in main
runners, cross runners, wall moldings, splines or nailing bars manufacturer for accessory items such as formed wire hangers,
spring spacer clips, tile retainers, and spacer bars shall be such
TABLE 1 Minimum Load-Carrying Capabilities of Main Runner
Members
TABLE 2 Straightness Tolerances of Structural Members of
Suspension Systems
Suspension System
Main Runner
lb/linear ft (kg/m)
Members Deformation Straightness Tolerances
Direct Hung Indirect Hung Furring Bar
Light-duty 5.0 (7.4) 2.0 (3.0) 4.5 (6.7) Bow ⁄32 in. in any 2 ft (1.30 mm/m)
Intermediate-duty 12.0 (17.9) 3.5 (5.1) 6.5 (9.7) Camber ⁄32 in. in any 2 ft (1.30 mm/m)
Heavy-duty 16.0 (23.8) 8.0 (11.9) . Twist 1° in any 2 ft (1.64°/m)
C 635
as to ensure satisfactory performance of their intended function a special order item arranged for, and agreed upon in advance
in the suspension system. Failure attributable to such accesso- between the purchaser and the seller.
ries to control alignment, prevent undesirable rot
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