System
Good Construction Practices
Performance
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This section is an overview of good design, application, installation and safety concerns that should be addressed
when CGC鈥檚 products and systems are used. This section outlines some major issues, but is not intended to be a
comprehensive review. No attempt is made at completeness.
We recommend that architects and contractors seek the assistance of safety professionals, especially at the
professional construction site, because there are many factors to consider that are not included here. For more
detailed information and references, please refer to Chapter 13 (Safety Considerations, Material Handling) of the
CGC Construction Handbook.
System Performance CGC Inc. conducts tests on products and systems to meet performance requirements of established test
procedures specified by various agencies. Upon written request we will provide test certification for published fire,
sound, structural and other pertinent data covering systems designed and constructed according to our published
specifications. Substitutions of any of the components are not recommended and are not endorsed by CGC Inc.
Fire Resistance Use fire test data to compare and select materials and constructions. In addition, these data are essential for
securing acceptance by the building code or agency having jurisdiction. The CGC Construction Selector (SA100)
shows tested fire resistance for various systems.
What is fire resistance?
Fire resistance refers to the ability of an assembly to serve as a barrier to fire and to confine its spread to the
area of origin. Spread of fire from one area to another occurs due to the following conditions:
(a) the barrier collapses
(b) openings in the barrier allow passage of flame or hot gases
(c) sufficient heat is conducted through an assembly to exceed specified temperature limitations
These characteristics form the basis for judging when an assembly no longer serves as a barrier in a test.
What is a fire resistance rating?
A fire resistance rating denotes the length of time a given assembly can withstand fire and give protection
from it under precisely controlled laboratory conditions.All tests are conducted in accordance with the Standard
CAN/ULC S101 or ASTM E119: Fire Tests of Building Construction and Materials.The standard is also known as
ANSI/UL 263 and NFPA 251. Fire resistance ratings are expressed in hours and apply to walls, floor- and roof-ceiling
assemblies, beams, and columns.
Can I substitute or add materials in a design?
For assemblies tested at Underwriters Laboratories Canada (ULC) or Underwriters Laboratories Inc. (UL), ratings are
specific to the designs tested.This is of particular importance when faced with alternate product or construction
suggestions. For example, insulation may not be added to floor- or roof-ceiling assemblies, unless described in the
ULC/UL design.Addition of insulation in the concealed space between the ceiling membrane and the floor or roof
structure may reduce the hourly rating of an assembly by causing premature disruption of the ceiling membrane
and/or higher temperatures on structural components under fire exposure conditions.
Increasing the size and gauge of the stud does not impact the fire resistance rating of the assembly.
For more detailed information, refer to the CGC Construction Selector (SA100) or the Underwriters Laboratories
Canada Fire Resistance Directory or the Underwriters Laboratory Fire Resistance Directory, Volume One.
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Structural Criteria Design of any structure must take into account the kinds of conditions that will exist and the resulting stresses
and movements. Load-bearing walls include the exterior walls of a building and some interior walls too. These
structures must be designed to carry the weight of the structure, its components, and other loads that occur once
the building is occupied.
The amount of axial load that structural members can bear will vary with the amount of lateral load (pressure from
wind or other horizontal stresses) that the final assembly may incur.
Manufacturers of structural components, particularly steel framing (studs, runners, joists) provide tables that
identify the maximum allowable loads for various components under specific conditions. These tables typically
start at 240 Pa (5 psf) lateral loads and increase in 240 Pa or 480 Pa (5 or 10 psf) increments to about
1920 Pa (40 psf). Interior partitions are typically designed for 240 Pa (5 psf) lateral loads.
Interior non-bearing partitions are not designed to carry axial loads. Limiting heights are based on stress or
deflection limits for given lateral loads. Height limitations depend on the gauge of the steel used, dimensions
of the stud, stud spacing, and the allowable deflection limit.
Control Joints 鈥? CGC is unable to determine specific location of control joints. Locating control joints is the responsibility of the
Building Movement design professional/architect. Integrate these suggestions with project conditions when determining specific
locations for control joints.
What are control joints and how are they used?
Control joint is a general term for methods used to minimize (not eliminate the potential for) cracking in partitions
and ceilings. Specifically, a control joint minimizes cracking in the face of a partition or ceiling. At the perimeter
of a partition or ceiling it is actually called a perimeter relief joint.
A control joint is effective in minimizing cracking caused by tensile or compressive movement in a membrane
resulting from thermal, hygrometric and structural effects.
Where should I consider a control joint?
Isolate surfaces with control joints or other means where:
(a) construction changes within the plane of the wall
(b) partition run exceeds 9 m (30 )
(c) expansion or control joints occur through the building itself
Ceiling-height door frames may be used as control joints. Less-than-ceiling-height door frames should have
control joints extending to ceiling from both corners on both sides of the partition. Treat window openings in same
manner as doors.
Zinc control joints, when properly insulated and backed by gypsum panels, have been fire-endurance tested
and are certified for use in one- and two-hour fire-rated walls.
Proper installation of control joints in partitions and ceilings requires breaking the gypsum panels or lath behind the
control joint. In ceiling construction, the framing should also be broken. In partitions, separate studs are used on
each side of the joint with the runner track separated at that location.
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Sound Control Use sound test data to compare and select materials and constructions. These data frequently are essential for
securing compliance by the agency having jurisdiction. The CGC Construction Selector (SA100) provides tested
acoustical performance for various systems.
What is sound control?
Sound control refers to the ability to attenuate sound passing through a partition.
The Sound Transmission Class (STC) is a widely used rating of sound attenuation performance. It is relatively
accurate for speech sounds but not for music, mechanical equipment noise or any sound with substantial low-
frequency energy. It is tested per ASTM E90 and rated per ASTM E413.
Sound tests are conducted under ideal laboratory conditions per ASTM procedures. CGC products are assembled
in a specific manner to meet the requirements of these ASTM procedures. Substitution of materials other than
those tested or deviation from the specified construction may adversely affect performance.
Field performance depends on building design and careful attention to detailing and workmanship. Where these
partitions are used for sound control, seal the partition perimeter with 6.4 mm (1/4 ) min. round bead of Acoustical
Sealant.
Seal around all cutouts for lights, cabinets, pipes, ducts and electrical boxes. Avoid back-to-back penetrations
of the diaphragm, flanking paths and door and borrowed-light openings.
Moisture, Mould Understanding moisture, mould and mildew and their impact on the construction process and building materials
And Mildew is integral to good design and construction practices. CGC offers references and additional sources that reinforce
good design, construction and maintenance practices. These practices are generally recognized as necessary to
minimize moisture-related problems and the growth of mould and mildew in a building environment. If you have
additional questions please contact those sources or CGC.
Mould and mildew are microorganisms that are present everywhere 鈥? indoors and outdoors. Mould and mildew
grow in or on virtually every construction material currently made. The best way to address mould and mildew is to
make sure that building materials do not get wet before and during installation and are not exposed to moisture
inside the finished building.
In all situations, immediately identify and address the cause of water damage to prevent re-occurrence of the problem.
For additional information, please use the following resources:
Canada's Indoor Environmental Program: http://www.nrc.ca/irc/ie
New York City Department of Health: http://nyc.gov/html/doh/home.html (Search for mould resources.)
U.S. Environmental Protection Agency: www.epa.gov (Search for mould resources.)
CGC literature: Moisture, Mould, Mildew and Construction Practices (EWB-0W95)
Moisture Control, System Performance (EWB-W111)
Air and Water Flashing and sealants as shown in the construction documents and as selected by the architect and/or structural
Infiltration engineer should be provided to resist air and water infiltration. The flashing and sealants selected shall be installed
in a workmanlike manner in appropriate locations to maintain continuity of air/water barriers, particularly at windows,
doors and other penetrations of exterior wall.
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Vapor Retarders Water vapor control must always be considered in the design of exterior wall systems. Humidity and temperature
conditions may require the installation of a vapor retarder to prevent moisture condensation within the wall and the
resulting damage. To determine the necessity and location of vapor retarders, a water vapor transmission and dew
point analysis of the layered wall assembly should be conducted by a qualified engineer.
Product Handling Gypsum Panels 鈥? Protect all gypsum products from exposure to excessive or continuous moisture and the elements
and Storage before, during and after installation. Eliminate sources of moisture immediately.
Metal Framing Protection 鈥? Give light gauge metal components such as steel studs and runners, furring channels
and resilient channels adequate protection in the warehouse and on the jobsite against rusting caused by moisture.
In marine areas such as the Caribbean, Florida and the Gulf Coast where chloride and sea salt are present in
combination with excessively high humidity, use of components which offer increased protection against corrosion
is recommended.
For additional information, refer to Storage and Handling, Wallboard and Other Products (EWB-W108).
Painting Systems Painting products and systems should be used which comply with recommendations and requirements in
Appendixes of ASTM C840. For priming and decorating with paint, texture or wall covering, follow manufacturer鈥檚
directions for materials used.
All surfaces, including applied joint compound, must be thoroughly dry, dust-free, and not glossy. Prime with
CGC First Coat or with an undiluted, interior latex flat paint with high-solids content. Allow to dry before decorating.
To improve fastener concealment, where gypsum panel walls and ceilings will be subjected to severe artificial or
natural side lighting and be decorated with a gloss paint (egg shell, semi-gloss or gloss), the gypsum panel surface
should be skim coated with joint compound to equalize suction and texture differences between the drywall face
paper and the finished joint compound before painting.
Trademarks Notice Safety First!
CGC Inc. is a licensed user of We shall not be liable for inci- Follow good safety and industrial
the trademark SHEETROCK. dental and consequential dam- hygiene practices during
ages, directly or indirectly sus- handling and installing of all
tained, nor for any loss caused products and systems. Take
by application of these goods necessary precautions and
not in accordance with current wear the appropriate personal
printed instructions or for other protective equipment as needed.
than the intended use. Our Read material safety data
liability is expressly limited to sheets and related literature
replacement of defective goods. on products before specification
Any claim shall be deemed and/or installation.
waived unless made in writing
to us within thirty (30) days
from date it was or reasonably
should have been discovered.
CGC Inc. www.cgcinc.com EWB-W106/4-03
漏2003, CGC Inc. CP
350 Burnhamthorpe Rd., W., 5th Fl.
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