- ULC Design Numbers (published in the Fire Resistance Directory of Underwriters Laboratories of Canada) and NRCC Report/Assembly Numbers (research publications of the Institute for Research in Construction, National Research Council of Canada) should be referenced when considering steel floor, wall and roof assembly designs in Canadian Building Code jurisdictions.
- For non-load bearing wall assemblies, steel stud thickness as per ASTM C 645, Standard Specification for Nonstructural Steel Framing Members, where minimum thickness is specified as 0.0179 in. (0.455 mm) before application of protective coating or in conformance with Section 9.
- UL non-load bearing wall and load bearing wall assemblies provide stud material thickness with a Manufacturers’ Standard Gauge (MSG) number. UL’s “BXUV.GuideInfo, Fire Resistance Ratings – ANSI/UL 263” provides the following thickness tables where an MSG is stated in the fire rated design.For load-bearing steel studs:
MSG Minimum bare metal thickness (in.)
20 0.0329
18 0.0428
16 0.0538
14 0.0677
For non-load bearing steel studs:
MSG Minimum bare metal thickness (in.)
25 0.0179
22 0.0269
20 0.0329
18 0.0428
16 0.0538 - Both the SFIA and the SSMA code compliance certification programs have developed minimum requirements that must be satisfied in order for a nonstructural stud to be considered an equivalent gauge stud (EQ stud). These criteria are to insure that the EQ stud will perform as well or better than the stud it replaces. A nonstructural EQ stud must meet the following criteria:
• Have an allowable or nominal bending moment that is at least equal to that of their traditional stud counterpart as listed in ASTM C645, Table 2.
• Must have developed and published composite limiting height tables in accordance with ICC-ES AC86 – 2010.
• Must have published screw data (shear and pullout) that is equal or greater than the traditional ASTM C645 stud.
• Must pass the screw penetration test in ASTM C645.
• Must meet the corrosion protection requirements of ASTM C645.
Fire assemblies that have EQ studs listed within the assembly are indicated with the following symbol: EQ studs can also be used in assemblies if they meet the minimum physical requirements described within the assembly.
Products delivered to the jobsite with SFIA or SSMA labels on the packaging assure the user that the studs are code compliant, meet the requirements above, and were subjected to independent third party certification to these requirements. - The majority of sound data that has been incorporated into this guide were based on the following report:Warnock, A.C.C., Estimation of Sound Transmission Class and Impact Insulation Class Rating for Steel Framed Assemblies, Report No. B3436.1 Revised, Institute for Research in Construction, National Research Council of Canada, Ottawa, Ontario, Canada, November 2008.The above report has surveyed existing published sound test reports denoted in the source column by an alphanumeric acoustic test identifier. Letter prefixes in the identifier denote various acoustic testing laboratories. The report also provides numerous acoustic “estimates” and these have been noted with an asterisk that refers to the above report, i.e., Warnock (2008). The report is available as a Steel Framing Alliance Research Report (RP08-7) from the Cold-Formed Steel Engineers Institute (https://cfsei.memberclicks.net/research-reports) as a free download in the form of an Adobe Acrobat file. Acoustic estimates were made with an acoustic “SOund Classification RATing EStimator” called “Socrates”.Further information on “Socrates” is also available via the following website:
http://www.alfwarnock.info/sound/socindex.htmlAcoustic data in some cases appears with the following codes to denote a material:AIR – a gap in the construction (a layer of air with thickness)
CAR-UND – carpet and underpad
CEMBRD – cement board (with thickness)
CER-PAD – ceramic tile and rubber pad
G – gypsum board (with thickness)
GFB – glass fiber batts (with thickness)
NI – no insulation
NRC – no resilient metal channels
RC – resilient metal channels
RFB – rock fiber (mineral wool) batts (with thickness)Acoustic reports if available for floor/ceiling and wall assemblies are noted in source column with acronyms for sound testing agencies before report numbers. The acronyms refer to the following sound testing agencies:
ASL – Acoustic Systems Acoustical Research Facility
BBN – Bolt, Beranek, and Newman, Inc.
CK – Cedar Knolls Acoustical Laboratories (now Electrical Testing Laboratories, ETL)
NGC – National Gypsum Company’s Gold Bond Laboratories (now NGC Testing Services)
NRCC – National Research Council of Canada (report numbers preceded by NRC TL, TLA, TLF or TL for Sound Transmission Class and IIF for Impact Insulation Class)
RAL – Riverbank Acoustical Laboratories
SA – Shiner & Associates
USG – USG Research & Technology Center - Information on UL fire rated cold-formed steel truss assemblies is available from the Cold-Formed Steel Council via the following webpage: http://www.cfsc.sbcindustry.com/docs/Fire_Assemblies_SSC.pdf
- Details of UL and ULC listings for fire rated floor, wall and truss assemblies can be downloaded from the website of UL and ULC by using the alphanumeric fire identifier within a keyword search. For example, on the UL website enter the following information:
– go to UL website at: http://www.ul.com/global/eng/pages/
– click on “Online Certifications Directory” located at the bottom, right side of webpage
– type in alphanumeric fire identifier, for example “L568” in keyword box and click on “Search”
– go to row with “Design No. L568” and click on “BXUV.L568”Similarly for the ULC website enter the following information:
– go to ULC website at: http://www.ul.com/canada/eng/pages/index.jsp
– click on “ULC Online Directories” located along left side of webpage
– in “Keyword” type in alphanumeric fire identifier, for example “M511” in keyword box and click on “Search”
– go to row with “Design No. M511” and click on “BXUVC.M511” - UL Floor and Load Bearing Wall Designs using cold-formed steel joists and studs can be used for Canadian application without a Load Restriction, i.e., a “Load Restricted Factor” equal to 1.00. Details regarding this restricted load use condition have been added to “BXUV7.GuideInfo, Fire Resistance Ratings – CAN/ULC-S101 Certified for Canada”. The percent load reductions in Table 1 of “BXUV7.GuideInfo” for typical assemblies are based upon loading calculated in accordance with the working stress design method as compared to loading calculated in accordance with the limit states design method. The fire resistance ratings for floors supported by cold-formed steel channels and walls supported by cold-formed steel studs do not have a Load Restriction Factor because the associated loads in Canada and the U.S. are based on the same standard: CSA S136-16, “North American Specification for the Design of Cold-Formed Steel Structural Members”, and ANSI/AISI S100-16, “North American Specification and Commentary for the Design of Cold-Formed Steel Structural Members”.
- As per UL’s “BXUV.GuideInfo, Fire Resistance Ratings – ANSI/UL 263” and ULC’s “BXUVC GuideInfo, Fire Resistance Ratings (Guide No. 40 U18)” the dimensions and thickness (gauge) of steel studs and joists are minimums. The hourly ratings apply when the steel studs and joists are larger in thickness (heavier gauge) and/or have larger dimensions than specified in a design, or when the member spacing is less than what was tested.
- In Canada, the 2015 edition of the National Building Code of Canada (NBCC) the sound insulation requirements for Group C residential occupancies are now given in terms of Apparent Sound Transmission Class (ASTC). Previous editions of the NBCC focused on the performance of the separating element only, with requirements given in terms of Sound Transmission Class (STC) ratings. The Code requires that a dwelling unit shall be separated from every other space in a building by an assembly (Walls of Floors/Ceilings) that will provide an ASTC rating not less than 47. ASTC considers the sound transmission via the direct path (i. e. through the separating wall or floor/ceiling) and via the flanking paths (e. g. via a shared floor or ceiling).The National Research Council Canada (NRCC) was involved with several joint projects with Canadian industry. For example, a joint research project between the NRCC and the Canadian Sheet Steel Building Institute investigated the sound transmission characteristics of cold-formed steel-framed constructions. The objective of the project was to provide data on direct and flanking sound transmission for common construction details in lightweight steel-framed mid-rise building construction market. Comprehensive results from the project are incorporated into the NRCC Research Report RR-337, “Apparent Sound Insulation in Lightweight Steel-Framed Buildings”, published in 2016. Report RR-337 in addition to reporting on flanking sound transmission also presents direct sound transmission STC values measured for wall assemblies in Table 2.2.1 and floor assemblies in Table 2.3.1.
NRCC has also developed a soundPATHS web application for design professionals that provides a prediction tool for the calculation of direct and flanking sound transmission between adjacent rooms. The software uses the calculation procedure outlined in the 2015 edition of the NBCC. The application has been designed so that the results from the application can be used to determine compliance versus having to laboratory test a wall or floor/ceiling assembly. The soundPATHS software is via the following NRCC webpage:
http://www.nrc-cnrc.gc.ca/eng/solutions/advisory/soundpaths/index.html
