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CPA T-Bar Guidelines Page 1 of 15
Revision Date: 10/2012
General Requirements/Checklist for:
Commercial
SUSPENDED CEILING
SYSTEMS INSPECTION
City of Palo Alto (CPA)
Building Inspection Division Inspection Request Line: 650 329-2496
Building Division Inspection Code IVR# 304
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 tomeet seismic requirements set forth in CISCA 3-4/UBC Standard 47-18. (See CISCA Guidelinesfor 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 forSeismic 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 beinstalled per manufacturer’s instruction and ICC-ESR reports information.
In each orthogonal (orthogonal means "involving right angles") horizontal direction, oneend 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 thewall 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 structuralsystem 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 0.25inch for the loads prescribed in Section 13.3.1.
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CPA T-Bar Guidelines Page 2 of 15
MINIMUM CODE REQUIREMENTS (continued)
o
For ceiling areas exceeding 2,500 ft2, a seismic separation joints or full height partition thatbreaks the ceiling up into areas not exceeding 2,500 ft2 shall be providedEXCEPTION
Structural analyses of the ceiling bracing system for the prescribed seismic forces thatdemonstrate ceiling system penetrations and closure angles provide sufficient clearanceto accommodate the anticipated lateral displacement.
o
Except where rigid braces are used to limit lateral deflections, sprinkler heads and otherpenetrations shall have a 2 inches oversize ring, sleeve, or adapter through the ceiling tileto 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 allhorizontal directions is permitted to be provided at the top of the sprinkler headextension. (see example illustrations for flex drops)
o Changes in ceiling plan elevation shall be provided with positive bracing. (See exampleillustrations below)
o
Cable trays and electrical conduits shall be supported independently of the ceiling per ASCE7-05 chapter 13 requirements.
o
Integral Construction. As an alternate to providing large clearances around sprinklersystem penetrations through ceiling systems, the sprinkler system and ceiling grid arepermitted 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, includingthe 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 supportedindependently a maximum of 8” inches from each wall or ceiling with number12 gage wire orapproved 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’ oncenter or #10 gauge at 5’ on center along each main runner.
Compression strut/seismic posts are typically required every 144 sq. ft., starting a maximum6’-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 heightshall 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 becompatible with ceiling deflection requirements as determined in Section ASCE 7-0513.5.6 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 theheight (ft) of the partition.
3) The partition horizontal seismic load does not exceed 5 psf.
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CPA T-Bar Guidelines Page 3 of 15
Fire ratings shall comply with the requirements of the 2010 California Building Code chapter7, UL listing, Office of the State Fire Marshal’s listing, and installation per the manufacturer’ssuspended 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 notbeen tested as a complete assembly are not acceptable .
o
For schools and Essential Services Buildings, bracing assemblies are required for each 96square 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 cut-
outs 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 effectivelyand 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 decorativeceiling allowing access to the concealed space.
ABOVE CEILING INSULATION
Concealed installation. Insulating materials, where concealed as installed in buildings ofany type of construction, shall have a flame spread index of not more than 25 and a smoke-
developed 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 tofacings, coverings, and layers of reflective foil insulation that are installed behind and insubstantial contact with the unexposed surface of the ceiling, wall or floor finish. (2010CBC 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 anytype of construction , shall have a flame spread index of not more than 25 and a smoke-developed index of not more than 450. (2010 CBC 719.3)
Surface insulation or other purposes shall be considered interior finish if they cover 10percent 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 thepaper.
o
Quilted foil-backed or un-faced fiberglass batts and blankets are better suited to conditionsof 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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CPA T-Bar Guidelines Page 4 of 15
ELECTRICAL Abandoned cables are not permitted to remain. CEC 800.52 (b
Junction boxes and similar enclosures shall be accessible and shall have required workingclearances 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 metalscrews. Minimum of two screws are to be installed on each side of the terminal, near thecorners, and fastened into the main runners.
Air terminals weighing 20 lbs but not more than 56 pounds, in addition to the above, shallhave two #12-gage hangers connected from the terminal or service to the ceiling systemhangers 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 structureabove 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, orsensing 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 tothe 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 approvedhangers.
o
Pendant Hung Fixtures shall be supported directly from the structure above with #9 gaugewire 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 inSection 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, orgroove type couplings, similar to Victaulic couplings, where the grooves in the pipe havebeen roll formed rather than cut.
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CPA T-Bar Guidelines Page 5 of 15
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 thatare joined by threading, bonding, or the use of groove type couplings where the grooves inthe 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 inlength 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 inlength 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 itshangers without introducing a bending moment in the hanger.o
There must be sufficient space around the piping run to accommodate the expected motionof 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/orselected to accept the full range of motion expected for both the pipe and the interfacingcomponent.
Single Clevis Supported Pipe in Seismic Design Categories D (ASCE 7-05 Sections 13.6.8-2a and13.6.8-2c)
For single clevis supported piping in buildings assigned to Seismic Design Categories D forwhich the Component Importance Factor is equal to 1.5, and for which the nominal size is 1inch or less; no seismic restraint is required.
For single clevis supported piping in buildings assigned to Seismic Design Categories D forwhich the Component Importance Factor is equal to 1.0, and for which the nominal size is 3inches or less; no seismic restraint is required.
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CPA T-Bar Guidelines Page 6 of 15
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 supportedpipe.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 thisissue and can make the following recommendations on the application of the exemptions inSections 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 buildingstructure, or to protect the pipe from such impact.
Trapeze Supported Pipe in Seismic Design Category D: (ASCE 7-05 Sections 13.1.4-5, 13.6.8-2a, 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 buildingmay increase the Seismic Design Category in order to ensure an adequate safety margin and thecontinued 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 pipingsystems to be seismically restrained. Careful attention to the specification must be paid, as someor all of the exemptions in this section may be nullified by specification requirements that aremore stringent than those provided by the code.
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CPA T-Bar Guidelines Page 7 of 15
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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CPA T-Bar Guidelines Page 6 of 12
EXAMPLES OF FLEXIBLE SPRINKLER SUSPENDED CEILING SYSTEM ATTACHMENTS
If the "cross-runners" are not the scarrying capacity as the "main-runnsupplementary #12 gauge hangerwires shall be attached at each sid
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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
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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 lon
Scope
Sec. 47.1808. This standard describes procedures for the installation o suspen
sion 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
brac
ing,
countersplaying or other acceptable means.
Hangers formed from galvanized sheet metal stock shall be suitable for suspend
ing
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-an
nealed 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
o
leveling car
rying
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
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988 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
per-
formed 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
X
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 con
tinuous main) member.
e) Splines. Splines used to form a concealed mechanical joint seal between adja
cent 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 im
posed
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 nd
within a horizontal distance of 0.0
S
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 im
posed 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
e x ~ e d
the deflection capability of
the
ceiling suspension system.
In
such cases, the fixture load shall be supported by sup
plemental 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 eccen
trically loaded except where provision
is
inherent in the system or
is
separately
pro-
vided for)
to
prevent undesirable section rotation or displacement, or both.
In
ny
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.
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47 18
U.B.C. STANDARDS
Part l l l 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
~ t a n d a r d s
2. Ceilings constr11ctrd of l ~ t h and plaster or gypsum board. screw or nail attached to
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
3
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 u 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 load
carrying 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 displac
1
ement 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
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988 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
5
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
i n u t l ~ c t l 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.
or
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 8 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
-
8/20/2019 Seismic Suspend Ceiling-1
30/30
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.
Mechanical Services
t
J J
•
2. S
C Q f 2 1.-1.. ')'
I\'-.) tb
,.,,
-'
\ i ~ \A A A 11 j2. \..- .. tv V R.._
. ~ n t e d air terminals or services weighing
less'
tthan
20
pounds shall
be
ositivel attache_
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