CPA T-Bar Guidelines
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SUSPENDED CEILING
SYSTEMS INSPECTION
Building Division
City of Palo Alto (CPA)
Building Inspection Division
Inspection Request Line: 650 329-2496
Inspection Code IVR# 304
Revision Date: 10/2012
General Requirements/Checklist for:
Commercial
Codes/Standards Enforced:
2010 CBC, ASCE 7-50, ASTM C
635, 636, CISCA 3-4
Palo Alto Municipal Code (PAMC)
The information provided in this document is general and intended as a guide only. Each project is unique and
additional requirements may be enforced as deemed appropriate.
REQUIRED ITEMS
 All existing tenant improvement suspended ceiling systems installed prior to January 1,
2008 in areas affected by renovation, structural repair, or alterations must be upgraded to
meet seismic requirements set forth in CISCA 3-4/UBC Standard 47-18. (See CISCA Guidelines
for Seismic Upgrade requirements following checklist)
PLANS/SHOP DRAWINGS/ICC ES REPORT
 Contractor shall provide City of Palo Alto Inspector with engineered “heavy duty” suspended
ceiling system plans/shop drawings/manufacturer’s installation requirements at time of
inspection.
 Plan must include engineering specifications for compression struts, wall attachments, and
layout for seismic joints when areas in excess of 2500 square feet.
 Provide inspector with current ICC ES Report for suspended ceiling system.
SPECIAL INSPECTION
 City of Palo Alto adopted policy #15 on 07/09/2009 of ICC Tri-Chapter Uniform Code
Committee - Special Inspection is not required for suspended ceiling.
MINIMUM CODE REQUIREMENTS
 Suspended Ceilings (2010 CBC 2506.2.1/ASCE 7-05 13.5.6)
o Seismic Design Categories D requirements for Suspended Ceiling Systems shall be
designed and installed in accordance with ASTM C635, ASTM C636, and the CISCA for
Seismic Zones 3-4 as modified by the following:
 A heavy duty T-bar grid system shall be used.
 The width of the perimeter supporting closure angle shall be not less than 2 inches.
Approved perimeter seismic clips may be used in lieu of 2 inch wall angle and shall be
installed per manufacturer’s instruction and ICC-ESR reports information.
 In each orthogonal (orthogonal means "involving right angles") horizontal direction, one
end of the ceiling grid shall be attached to the closure angle.
 The other end in each horizontal direction shall have a 0.75 inches clearance from the
wall and shall rest upon and be free to slide on a closure angle.
o For ceiling areas exceeding 1,000 ft2, horizontal restraint of the ceiling to the structural
system shall be provided.
 The tributary areas of the horizontal restraints shall be approximately equal.
(Manufacturer may required vertical post every 12 square feet)
EXCEPTION:
 Rigid braces are permitted to be used instead of diagonal splay wires.
 Braces and attachments to the structural system above shall be adequate to limit
relative lateral deflections at point of attachment of ceiling grid to less than 0.25
inch for the loads prescribed in Section 13.3.1.
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MINIMUM CODE REQUIREMENTS (continued)
o For ceiling areas exceeding 2,500 ft2, a seismic separation joints or full height partition that
breaks the ceiling up into areas not exceeding 2,500 ft2 shall be provided
EXCEPTION
 Structural analyses of the ceiling bracing system for the prescribed seismic forces that
demonstrate ceiling system penetrations and closure angles provide sufficient clearance
to accommodate the anticipated lateral displacement.
o Except where rigid braces are used to limit lateral deflections, sprinkler heads and other
penetrations shall have a 2 inches oversize ring, sleeve, or adapter through the ceiling tile
to allow for free movement of at least 1 inch in all horizontal directions.
 Alternatively, a swing joint that can accommodate 1 inch of ceiling movement in all
horizontal directions is permitted to be provided at the top of the sprinkler head
extension. (see example illustrations for flex drops)
o Changes in ceiling plan elevation shall be provided with positive bracing. (See example
illustrations below)
o Cable trays and electrical conduits shall be supported independently of the ceiling per ASCE
7-05 chapter 13 requirements.
o Integral Construction. As an alternate to providing large clearances around sprinkler
system penetrations through ceiling systems, the sprinkler system and ceiling grid are
permitted to be designed and tied together as an integral unit. (ASCE 7-05 13.5.6.3)
 Such a design shall consider the mass and flexibility of all elements involved, including
the ceiling system, sprinkler system, light fixtures, and mechanical (HVAC)
appurtenances. Such design shall be performed by a registered design professional.
 Perimeter hangers - terminal ends of each cross runner and main runner shall be supported
independently a maximum of 8” inches from each wall or ceiling with number12 gage wire or
approved wall support.
 Vertical wires shall be attached to the suspension member and to the support above with a
minimum of three turns.
 Trapeze or equivalent device may be used where obstruction precludes direct suspension.
 Seismic separation joints shall be installed per manufacturer’s specifications & approved plans.
 Vertical hangers: Suspension wires shall not be smaller than #12 gauge spaced at 4’ on
center or #10 gauge at 5’ on center along each main runner.
 Compression strut/seismic posts are typically required every 144 sq. ft., starting a maximum
6’-0” from perimeter with seismic wires (4) directions @ max. 45 degrees from horizontal.
 Partitions Tied To Suspended Ceilings (ASCE 7-05 13.8)
o General. Partitions that are tied to the ceiling and all partitions greater than 6ft in height
shall be laterally braced to the building structure.
 Such bracing shall be independent of any ceiling splay bracing.
 Bracing shall be spaced to limit horizontal deflection at the partition head to be
compatible with ceiling deflection requirements as determined in Section ASCE 7-05
13.5.6 for suspended ceilings and elsewhere in this section for other systems.
EXCEPTION: Partitions that meet all of the following conditions:
1) The partition height does not exceed 9 ft.
2) The linear weight of the partition does not exceed the product of 10lb times the
height (ft) of the partition.
3) The partition horizontal seismic load does not exceed 5 psf.
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 Fire ratings shall comply with the requirements of the 2010 California Building Code chapter
7, UL listing, Office of the State Fire Marshal’s listing, and installation per the manufacturer’s
suspended ceiling system installation manual.
o The components and installation details must conform to the U.L. or SFM approval for the
design number specified.
o Custom designs which combine components from different approved designs but have not
been tested as a complete assembly are not acceptable.
o For schools and Essential Services Buildings, bracing assemblies are required for each 96
square feet.
o The first bracing assembly is required not more than four (4) feet from each wall.
o A minimum of one bracing assembly is required between any two adjacent expansion cutouts on runners being braced.
Fire Separation Marking and Identification Requirements
 Fire walls, fire barriers, fire partitions, smoke barriers and smoke partitions or any
other wall required to have protected openings or penetrations shall be effectively
and permanently identified with signs or stenciling. (2010 CBC section 703.6)
O Such identification shall:
 Be located in accessible concealed floor, floor-ceiling or attic spaces;
 Be repeated at intervals not exceeding 30 feet measured horizontally along the wall or
partition; and
 Include lettering not less than 0.5 inch in height, incorporating the suggested wording:
"FIRE AND/OR SMOKE BARRIER-PROTECT ALL OPENINGS," or other wording.
Exception: Walls in Group R-2 occupancies that do not have a removable decorative
ceiling allowing access to the concealed space.
ABOVE CEILING INSULATION
 Concealed installation. Insulating materials, where concealed as installed in buildings of
any type of construction, shall have a flame spread index of not more than 25 and a smokedeveloped index of not more than 450. (2010 CBC section 719.2)
o Facings. Where such materials are installed in concealed spaces in buildings of Type III,
IV or V construction, the flame spread and smoke-developed limitations do not apply to
facings, coverings, and layers of reflective foil insulation that are installed behind and in
substantial contact with the unexposed surface of the ceiling, wall or floor finish. (2010
CBC 719.2.1)
Exception:
 All layers of single and multilayer reflective plastic core insulation shall comply with
Section 2613.
 Exposed installation. Insulating materials, where exposed as installed in buildings of any
type of construction, shall have a flame spread index of not more than 25 and a smokedeveloped index of not more than 450. (2010 CBC 719.3)
 Surface insulation or other purposes shall be considered interior finish if they cover 10
percent or more of the wall or of the ceiling area, and shall not be considered decorative
materials or furnishings. (2010 CBC 806.1)
o Paper faced insulation is not permitted in exposed above ceiling areas, the open side of
furred spaces, and ventilated interstitial spaces due to the potential of embers igniting the
paper.
o Quilted foil-backed or un-faced fiberglass batts and blankets are better suited to conditions
of potential fire hazards.
o Use approved quilted foil-backed insulation such as “Reflectix Insulation” in areas where a
vapor barrier is required and use as a fix when paper back insulation is exposed.
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ELECTRICAL
 Abandoned cables are not permitted to remain. CEC 800.52 (b
 Junction boxes and similar enclosures shall be accessible and shall have required working
clearances CEC 314.29, 110.26(a)
 Cables and raceways shall not be supported by ceiling grids. CEC 300.11(a)
CEILING MOUNTED AIR TERMINALS
 Air terminals weighing less than 20 pounds shall be positively attached using sheet metal
screws. Minimum of two screws are to be installed on each side of the terminal, near the
corners, and fastened into the main runners.
 Air terminals weighing 20 lbs but not more than 56 pounds, in addition to the above, shall
have two #12-gage hangers connected from the terminal or service to the ceiling system
hangers or to the structure above. These wires may be installed with limited slack.
 Air terminals weighing more than 56 pounds shall be supported directly from the structure
above by approved hangers.
RETURN AIR PLENUMS
 Verify that all materials meet the applicable flame spread rating for return air plenums and
ducts noted as “plenum rated”.
 Equipment and devices shall be permitted only when necessary for their direct action upon, or
sensing of, the contained air. CEC 300.22 (b)
 Verify that fire damper is clear and operational. CBC
 Communication plenum rated cable (CMP) shall be listed as suitable for use in ducts,
plenums and listed as having adequate fire resistant and low smoke producing characteristics.
CEC 800.179 (a), CEC 800.154 (a)
LIGHTING FIXTURE SUPPORTS
 Only “Heavy-Duty” systems listed for Seismic Design Category D shall be used in the City of
Palo Alto.
 All lighting fixtures shall be positively attached to the suspended ceiling system with 4 screws typically one at each corner.
 Wires required to the fixture:
o Fixture less than 56 lbs: two no. 12-gage hangers connected from the fixture housing to
the structure above. These wires may be installed with limited slack.
o Fixtures more than 56 lbs shall be supported directly from the structure above by approved
hangers.
o Pendant Hung Fixtures shall be supported directly from the structure above with #9 gauge
wire without using the ceiling suspension system for direct support.
ASCE 7-05 CHAPTER 13 SEISMIC BRACING EXEMPTIONS FOR PIPING SYSTEMS
The exemptions that apply specifically to seismic bracing for piping systems are covered in
Section 13.6.8 of ASCE 7-05.
 The provisions of this section do not cover elevator system piping which is covered in Section
13.6.10 of ASCE 7-05.
 Also not covered in this section is fire protection piping. Fire protection piping will be covered
in a separate publication.
 The piping considered in this section is assumed to be high-deformability piping.
o This implies pipes made from ductile materials that are joined by welding, brazing, or
groove type couplings, similar to Victaulic couplings, where the grooves in the pipe have
been roll formed rather than cut.
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ASCE 7-05 CHAPTER 13 SEISMIC BRACING EXEMPTIONS FOR PIPING SYSTEMS
(continued)
 Limited deformability piping on the other hand, would be pipes made of ductile materials that
are joined by threading, bonding, or the use of groove type couplings where the grooves in
the pipe have been machine cut.
o Low deformability piping would be comprised of pipes made from relatively brittle materials
such as cast iron or glass.
The 12 inch Rule (ASCE 7-05 Section 13.6.8-1]1):
 No restraints will be required for piping that meets the requirements of the 12 inch Rule for
the entire piping run. The 12 inch Rule will be said to apply to a piping run if:
o The piping is supported by rod hangers.
o For single clevis supported pipe, all of the hangers in the piping run are 12 inches or less in
length from the top of the pipe to the supporting structure.
o For trapeze supported pipe, all of the hangers in the piping run are 12 inches or less in
length from the top of the trapeze bar to the supporting structure.
The past practice by SMACNA and other recognized authorities in the industry to call for the
connection between the hanger and the supporting structure to be “non-moment generating”.
 This means that the connector must be one that allows the piping run to swing freely on its
hangers without introducing a bending moment in the hanger.
o There must be sufficient space around the piping run to accommodate the expected motion
of the pipe as it sways back and forth with the earthquake motion in the building.
o Connections between the piping and the interfacing components must be designed and/or
selected to accept the full range of motion expected for both the pipe and the interfacing
component.
Single Clevis Supported Pipe in Seismic Design Categories D (ASCE 7-05 Sections 13.6.8-2a and
13.6.8-2c)
 For single clevis supported piping in buildings assigned to Seismic Design Categories D for
which the Component Importance Factor is equal to 1.5, and for which the nominal size is 1
inch or less; no seismic restraint is required.
 For single clevis supported piping in buildings assigned to Seismic Design Categories D for
which the Component Importance Factor is equal to 1.0, and for which the nominal size is 3
inches or less; no seismic restraint is required.
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Exemptions for Trapeze Supported Pipe per VISCMA Recommendations
Neither ASCE 7-98-02 nor ASCE 7-05 specifies how the piping is to be supported.
 The point is that many pipes of the exempted size may be supported on a common trapeze
bar using hanger rods of the same size as would be specified for a single clevis supported
pipe.
o Keep in mind that the purpose of the seismic restraints is to make sure the pipe moves
with the building.
o The amount of force that the hanger rod must carry will be a direct function of the weight
of pipe being supported.
o There must be some limit to how much weight a trapeze bar can support for a given
hanger rod size before seismic restraint is required.
VISCMA (Vibration Isolation and Seismic Control Manufacturer’s Association) has investigated this
issue and can make the following recommendations on the application of the exemptions in
Sections 5.4 and 5.5 above to trapeze supported pipe, www.viscma.com.
 The following basic provisions must apply:
o The hangers must be ASTM A36 all-thread rod.
o The threads must be roll formed.
o The pipes must be rigidly attached to the hanger rods.
o Provisions must be made to avoid impact with adjacent pipe, duct, equipment, or building
structure, or to protect the pipe from such impact.
Trapeze Supported Pipe in Seismic Design Category D: (ASCE 7-05 Sections 13.1.4-5, 13.6.82a, and 13.6.8-2c)
 For trapeze supported piping in buildings assigned to Seismic Design Category D, which have a
Component Importance Factor equal to 1.5, and for which the nominal size is 1 inch or less,
no seismic restraint is required if:
o The trapeze bar is supported by 3/8-16 UNC, or larger, hanger rods.
o The maximum hanger spacing is 7 ft. on center.
o The total weight supported by the trapeze bar is 4 lbs/ft or less.
 For trapeze supported piping in buildings assigned to Seismic Design Category D, which have a
Component Importance Factor equal to 1.0, and for which the nominal size is 3 inches or less,
no seismic restraint is required if:
o The trapeze bar is supported by ½”-13 UNC, or larger, hanger rods.
o The maximum hanger spacing is 10 ft. on center.
o The total weight supported by the trapeze bar is 25 lbs/ft or less.
 The Seismic Design Category to which the project has been assigned must be known.
o This should be noted on the issued permit plans.
o The design professional responsible for the piping system must assign an appropriate
Component Importance Factor to the system.
As a sidebar to the previous statement, it should be noted that the specification for the building
may increase the Seismic Design Category in order to ensure an adequate safety margin and the
continued operation of the facility. This is a common practice with schools, government buildings,
and certain manufacturing facilities.
The building owner has the prerogative, through the specification, to require all of the piping
systems to be seismically restrained. Careful attention to the specification must be paid, as some
or all of the exemptions in this section may be nullified by specification requirements that are
more stringent than those provided by the code.
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DETAILS
REFERENCES
STANDARDS
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EXAMPLES OF DRYWALLL SUSPENDED CEILING SYSTEM - NO MIXING COMPONENTS
EXAMPLES OF DRYWALLL SUSPENDED CEILING SYSTEM - NO MIXING COMPONENTS
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EXAMPLES OF FLEXIBLE SPRINKLER SUSPENDED CEILING SYSTEM ATTACHMENTS
If the "cross-runners" are not the same
carrying capacity as the "main-runner"
supplementary #12 gauge hanger
wires shall be attached at each side.
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EXAMPLES OF SEISMIC CONNECTORS FOR SUSPENDED CEILING SYSTEMS
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EXAMPLES OF SEISMIC CONNECTORS FOR SUSPENDED CEILING SYSTEMS
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EXAMPLES OF SEISMIC CONNECTORS FOR SUSPENDED CEILING SYSTEMS
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EXAMPLES OF SEISMIC CONNECTORS FOR SUSPENDED CEILING SYSTEMS
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STANDARD FOR EXISTING SUSPENDED CEILING SYSTEM
UPGRADES
U.B.C. STANDARD 47-18
T-BAR CEILING INSTALLATIONS
EXISTING SYSTEMS
Systems installed prior to Jan 1, 2008 shall be upgraded to meet 1997 Standards 47-18.
UBC STANDARD 47-18 INSTALLATION REQUIREMENTS AND ILLUSTRATIONS
Part 11-1 ns tall a tlon
Scope
Sec. 47.1808. This standard describes procedures for the installation of suspension systems for acoustical tile and lay-in panels.
Installation of Components
Sec. 47.1809. (a) Hangers. Hangers shall be attached to the bottom edge of the
wood joists or to the vertical face of the wood joists near the bottom edge. Bottom
edge attachment devices shall be an approved type.
In concrete construction mount hangers using cast-in-place hanger wires, hanger
inserts, or other hanger attachment devices shall be an approved type. If greater
center-to-center distances than 4 feet 0 inch are used for the hangers, reduce the
load-carrying capacity of the ceiling suspension system commensurate with the ac·
tual center-to-center hanger distances used.
Hangers shall be plumb and shall not press against insulation covering ducts or
pipes. If some hangers must be splayed, offset the resulting horizontal force by bracing, countersplaying or other acceptable means.
Hangers formed from galvanized sheet metal stock shall be suitable for suspending carrying channels or main runners from an existing structure provided that the
hangers do not yield, twist or undergo other objectionable movement.
Wire hangers for suspending carrying channels or main runners from an existing
structure shall be prepared from a minimum of No. 12-gage, galvanized, soft-annealed, mild steel wire.
Special attachment devices that support the carrying channels or main runners
shall be approved to support five times the design load.
(b) Carrying Channels. The carrying channels shall be installed so that they are all
level to within Y. inch i'n 12 feet.
Leveling shall be performed with the supporting hangers taut.
Local kinks or bends shall not be made in hanger wires as a means of leveling carrying channels.
In installations where hanger wires are wrapped around carrying channels, the
wire loops shall be tightly formed to prevent any vertical movement or rotation of
the member within the loop.
1368
1988 EDITION
47-18
(c) Msin Runners. Main runners shall be installed so that they are all level lO
within Y. inch in 12 feet.
Where main runners are supported directly by hangers, leveling shall be performed with the support.ing hanger taut.
Local kinks or bends shall not be made in hanger wires as a means of leveling
main runners.
In installations where hanger wires are wrapped through or around main runners,
the wire loops shall be tightly wrapped and sharply bent.
(d) Cross Runners. Cross runners shall be supported by either main runners or by
other cross runners to within X2 inch of the required center distances. This tolerance
shall be noncumulative beyond 12 feet.
Intersecting runners shall form a right angle.
The exposed surfaces of two intersecting runners shall lie within a vertical distance
of 0.015 inch of each other with the abutting (cross) member always above the continuous (main) member.
(e) Splines. Splines used to form a concealed mechanical joint seal between adjacent tiles shall be compatible with the tile kerf design so that the adjacent tile will be
horizontal when installed. Where splines are longer than the dimension between
edges of supporting members running perpendicular to the splines, place the splines
so that they rest either all above or all below the main running members.
(f) Assembly Devices. Abutting sections of main runner shall be joined by means
of suitable connections such as splices, interlocking ends, tab locks, pin locks, etc. A
joint connection shall be judged suitable both before and after ceiling loads are imposed if the joint provides sufficient alignment so that the exposed surfaces of two
abutting main runners lie within a vertical distance of 0.015 inch of each other and
within a horizontal distance of 0.0 IS inch of each other.
There shall be no visually apparent angular displacement of the longitudinal axis
of one runner with respect to the other.
Assembly devices shall provide sufficient spacing control so that horizontal gaps
between exposed surfaces of either abutting or intersecting members shall not exceed
0.020 inch.
Spring wire dips used for supporting main runners shall maintain tight contact
between the main runners and the carrying channels when the ceiling loads are imposed on the runners.
(g) Ceiling Fixtures. Fixtures installed in acoustical tile or lay-in panel ceilings
shall be mounted in a manner that will not compromise ceiling performance.
Fixtures shall not be supported from main runners or cross runners if the weight
of the fixtures causes the total dead load to exc~ed the deflection capability of the
ceiling suspension system. In such cases, the fixture load shall be supported by supplemental hangers within 6 inches of each corner, or the fixture shall be separately
supported.
Fixtures shall not be installed so that main runners or cross runners will be eccentrically loaded except where provision is inherent in the system (or is separately provided for) to prevent undesirable section rotation or displacement, or both. In any
case, runners supporting ceiling fixtures shall not rotate more than 2 degrees after
the fixture loads are imposed.
Where fixture installation would produce rotation of runners in excess of 2
degrees, install fixtures with the use of suitable accessory devices. These devices shall
support the fixture in such a manner that the main runners and cross runners will be
loaded symmetrically rather than eccentrically.
1369
U.B.C. STANDARDS
47-18
Part lll-Latmal Design Requirements
Scope
Sec. 47.1810. Snspencled ceiling which are designed and constructed to support ceiling
panels or tiles, with or without lighting fixtures, ceiling mounted air terminals or other
ceiling mounted services shall comply with the requirements of this standard.
EXCEPTIONS: I. Cci ling an· a of 14 4 square feet or less surrounded by walls which connect
dir..:ctly to the stn1cture above shnll be exempt from the lateral load design requirements of these
~tandards.
2. Ceilings constr11ctrd of l~th and plaster or gypsum board. screw or nail attached to
I
suspcndrd members tlmt support a ceiling on one level extending from wall to wall.
Minimum Design Loads
Sec 47.1811. (a) Lateral Forces. Such ceiling systems and their connections to the
building structure shall be designed and constructed to resist a lateral force specified in
Chapter 23 of !he Uniform Building Code.
Where the ceiling system provides lateral support for nonbearing partitions, it shall be
designed for the prescribed lateral force reaction from the partitions us specified in Section
47.1815.
Connection of lighting fixtures to the ceiling system shall be designed for a lateral force of
100 percent of the weight of the fixture in addition to the prescribed vertical loading as
specified in Section 47.1813.
(b) Grill Members, Connectors anu Expansion Devices. The main runners and cross
runners of the ceiling system and their splices, intersection connectors and expansion
devices shall be designed and constructed to carry a mean ultimate test load of not less than
180 pounds or twice the actual load, whichever is greater, in tension with a 5-degree
misalignment of the members in any direction, and in compression. In lieu of 5-degree
misalignment, the load may be applied with a l-inch eccentricity on a sample not more than
24 inches long each side of the splice. The connections at splices and intersections all shall be
of the mechanical interlocking type.
Where the composition or configuration of ceiling systems members or assemblies and
their connections are such that calculations of their allowable load-carrying capacity cannot
be made in accordance with established methods of analysis, their performance shall be
established by test.
Evaluation of test results shall be made on the basis of the mean values resulting from tests
of not fewer than three identical specimens, provided the deviation of any individual test
result from the mean value does not exceed plus or minus I 0 percent. The allowable loadcarrying capacity as determined \:ly test shall not exceed one half of the mean ultimate test
value.
(c) Substantiation. Each ceiling systems manufacturer shall furnish lateral loading
capacity and displac1ement or elongation characteristics for his systems, indicating the
following:
I. Maximum bracing pattern and minimum wire siz.es.
2. Tension and compression force capabilities of main runner splices, cross runner
connections and expansion devices.
All tests shall be conducted by an approved testing agency.
Installation
Sec. 47.1812. (a) Vertical Hangers. Suspension wires shall be not smaller than No. 12
gage spaced at ,1 feel on center or No. 10 gage at 5 feet on center along each main runner
unless calculations justifying the incre<1sed spacing are provided.
1988 EDITION
47-18
Each vertical wire shall be attached to the ceiling suspension member and to the support
above with a minimum of three turns. Any connection device at the supporting construe lion
shall be capable of carrying not less than 100 pounds.
Suspension wires shall not hang more than l in 6 out-of-plumb unless countcrsloping
wires are provided.
Wires shall not attach to or bend around interfering material or equipment. A trapeze or
equivalent device shall be used where obstructions preclude direct suspension. Trapeze
suspensions shall be a minimum of back-to-back 11/4-inch cold-rolled channels for spans
exceeding 48 inches.
(b) Perimeter Hangers. the terminal ends of each cross runner and main runner shall be
supported independently a maximum of 8 inches from each wall or ceiling discontinuity
with No. 12 gage wire or approved wall support.
•
(c) Lateral Force Bracing. Where substantiating design caltulations are not provided,
horizontal restraints shall be effected by four No. I 2 gauge wires secured to the main runner
within 2 inches of the cross runner intersection and and splayed 90 degrees from each other at
an angle not exceeding 45 degrees from the plane of the ceiling. A strut fastened to the main
runner shall be extended to and fastened to the structural members supporting the roof or
floor above. The strut shall be tH.lcquatc to resist the vertical component inutl~:ctl by the
bracing wires. These horizontal restraint points shall be placed 12 feet on center in both
directions with the first point within 6 feet from each wall. Attachment of the restraint wires
to the structure above shall be adequate for the load imposed.
Lateral force bracing members shall be spaced a minimum of 6 inches from all horizontal
piping or duct work that is not provided with bracing restraints for horizonta I forces. ·Bracing
wires shall be attached to the grid and to the structure in such a manner that they can support a
design load of not less than 200 pounds or the actual design load, whichever is greater, with a
safety factor of 2.
(d) Perimeter Members. Unless perimeter members are a structural part of the approved
system, wall angles or channels shall be considered as aesthetic closers and shall have no
structural value assessed to themselves or their method of attachment to the walls. For tile
ceilings, ends of main runners and .cross members shall be tied together to prevent their
spreading.
(e) Attachment of Members to the Perimeter. To facilitate installation, main runners
and cross runners may be attached to the perimeter member at two adjacent walls with
clearance between the wall and the runners maintained at the other two walls or as otherwise
shown or described for the approved system.
Lighting Fixtures
Sec. 47.1813. Only "intermediate" and "heavy duty" c;eiling systems as defined in
Section 47.1802 may be used for the support of lighting fixtures.
All lighting fixtures shall be positively attached to the suspended ceiling system. The
attachment device shall have a capacity of 100 percent of the lighting fixture weight acting in
any direction.
When" intermediate" systems are used, No. 12 gage hangers shall be attached to the grid
members within 3 inches of each corner of each fixture. Tandem fixtures may utilize
common wires.
Where "heavy duty" systems are used, supplemental hangers are not required if a 48- inch
modular hanger pattern is followed. When cross runners are used without supplemental
hangers to support lighting fixtures, these c;ross runners must provide the same carrying
capacity as the main runner.
Lighting fixtures weighing less than 56 pounds shall have, in addition to the require rnents
. 1371
47-18
U.B.C. STANDARDS
outlined above, two No. 12 gage hangers connected from the fixture housing to the structure
above. These wires may be slack.
. Lighting fixtures weighing 56 pounds or more shall be supported directly from the
structure above by approved hangers.
Pendant-hung lighting fixtures shall be supported directly from the stnrcture above using
No. 9 gage wire or approved alternate support wjthout using the ceiling suspension system
for direct support.
Minimum
each
~ t J..J • (2)
2. screws
'S C.Q.into
f,2 1.-1..)
"')' mainI\'-.)"tb
runner
,.,,...-' \i:~ ~ \A.A. A. 1 10 j2. \..-'.. tv IV ~ R.._
Mechanical Services
. ~nted air terminals or services weighing less' tthan 20
pounds shall be ositivel attache_<;!Jo the ceiling suspension main runners or to cro~.)
runners with the same carrying cap.acity as the main runners.
Terminals or services weighing 20 pounds but not more than 56 pounds, in addition to the above, shall have two No. J2 gage hangers connected from the terminal
or service to the ceiling system hangers or to the structure above. These wires may be
slack.
Terminals or services weighing more than 56 pounds shall be supported directly
from the structure above by approved hangers.
Partitions
Sec. 47.1815. Where the suspended ceiling system is required to provide lateral
support for permanent or relocatable partitions, the connection of the partition to
the ceiling system, the ceiling system members and their connections, and the lateral
force bracing shall be designed to support the reaction force of the partition from
prescribed loads applied perpendicular to the face of the partition. These partition
reaction forces shall be in addition to the loads described in Section 47.181 J. Partition connectors, the suspended ceiling system and the lateral force bracing shall all
be engineered to suit the individual partition application and shall be shown or
defined in the drawings or specifications.
Drawings and Specifications
Sec. 47.1816. The drawings shall clearly identify all systems and shall define or
show all supporting details, lighting fixture attachment, lateral force bracing, partition bracing, etc. Such definition may be by reference to this standard, or approved
system, in whole or in part. Deviations or variations must be shown or defined in
detail.
1372