[CCMC 12691-R] CCMC Canadian code compliance evaluation
From: National Research Council Canada
|Compliance:||NBC 2015, OBC|
In most jurisdictions this document is sufficient evidence for approval by Canadian authorities.Learn more about CCMC recognition Look for the trusted CCMC mark on products to verify compliance.
It is the opinion of the Canadian Construction Materials Centre that the evaluated products, when used as composite wood chord and steel web trusses in floor applications in accordance with the conditions and limitations stated in this evaluation, comply with the following code:
National Building Code of Canada 2015
|ID||Code provision||Solution type|
|09-10-08-10-00-0-00||188.8.131.52. Application to Houses||Alternative|
|09-23-04-02-00-0-00||184.108.40.206.(2) Spans for floor joists that are not sele ...||Alternative|
Ontario Building Code
Ruling No. 07-05-163 (12691-R) authorizing the use of this product in Ontario, subject to the terms and conditions contained in the Ruling, was made by the Minister of Municipal Affairs and Housing on 2007-02-20 pursuant to s.29 of the Building Code Act, 1992 (see Ruling for terms and conditions). This Ruling is subject to periodic revisions and updates.
The above opinion(s) is/are based on the evaluation by the CCMC of technical evidence provided by the evaluation holder, and is bound by the stated conditions and limitations. For the benefit of the user, a summary of the technical information that forms the basis of this evaluation has been included.
- Posi-Strut® Metal Web Joist PS-10V2
- Posi-Strut® Metal Web Joist PS-12
- Posi-Strut® Metal Web Joist PS-12i
- Posi-Strut® Metal Web Joist PS-13
- Posi-Strut® Metal Web Joist PS-14V3
- Posi-Strut® Metal Web Joist PS-16V3
The product is a composite wood chord and steel web truss (see Figure 1) used in floor applications. The product is manufactured in six (6) depths with several metal web configurations as outlined in the following table. PS-12i is from the PS-12 series with a special height to match a typical I-Joist depth of 302 mm (11-7/8 in.).
|“Posi-Strut® Metal Web” designation||Truss depth (mm (in.))|
|PS-10V2||235 (9 1/4)|
|PS-12||286 (11 1/4)|
|PS-12i||302 (11 7/8)|
|PS-13||324 (12 3/4)|
Parallel wood chords, placed on the flat, are connected with pairs of V-shaped, galvanized metal webs. The parallel chords have dimensions of 38 mm × 64 mm or 89 mm, and are made of either No. 2 or better Spruce-Pine-Fir (S-P-F) lumber or machine stress rated (MSR), kiln-dried lumber. The web elements of the product are manufactured from 0.91-mm-thick hot-dipped G-90 galvanized steel sheets conforming to ASTM A 653/A 653M-13, “Steel Sheet, Zinc-coated (Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed) by the Hot-dip Process,” Grade 40. The mounting teeth are integrally punched into the plate areas at the apex and at the ends of the web element (see Figure 2).
This evaluation is valid only for products produced at the following plant:
|Product names||Manufacturing plant|
|Bradford, ON, CA|
|Posi-Strut® Metal Web Joist PS-10V2||Product evaluated by the CCMC|
|Posi-Strut® Metal Web Joist PS-12||Product evaluated by the CCMC|
|Posi-Strut® Metal Web Joist PS-12i||Product evaluated by the CCMC|
|Posi-Strut® Metal Web Joist PS-13||Product evaluated by the CCMC|
|Posi-Strut® Metal Web Joist PS-14V3||Product evaluated by the CCMC|
|Posi-Strut® Metal Web Joist PS-16V3||Product evaluated by the CCMC|
Product evaluated by the CCMC Indicates that the product from this manufacturing facility has been evaluated by the CCMC
Conditions and limitations
The CCMC’s compliance opinion is bound by this product being used in accordance with the conditions and limitations set out below.
- The product is intended for structural applications such as floor, ceiling or roof joists, and is intended for dry service use application only.Footnote (1)
- The following pre-engineering has been provided to the CCMC by MiTek Canada Inc. to demonstrate compliance to Part 9, Housing and Small Buildings, for acceptance by the local authority having jurisdiction (AHJ):
MiTek Canada Inc’s pre-engineered floor span chartWhen the product is used to support uniform loads only, the installation must be in accordance with:
- Posi-Strut® Maximum Clear Span Tables (including vibration criteriaFootnote (2), in limit states design for Canada), dated October 2018; and
- MITEK POSI-STRUT Installation Guidelines, dated October 2018.
The product must be installed in accordance with MiTek Canada Inc.’s installation guidelines noted in these documents for those applications falling within the scope of the documents. Applications outside the scope of these installation guidelines require engineering on a case-by-case basis.
MiTek Canada Inc.’s pre-engineered installation details
MiTek Canada Inc.’s pre-engineered details within the documents outlined in (i) above are limited in scope to building designs where the anticipated loads on the following structural details are not exceeded:
- floor span tables;
- strongback installation details;
- top chord installation details; and
- rim board and ribbon details.
For structural applications beyond the scope/limitations of the above-referenced MiTek Canada Inc. publications, or when required by the AHJ, the drawings or related documents must bear the authorized seal of a professional engineer skilled in wood design and licensed to practice under the appropriate provincial or territorial legislation. Installations beyond the scope/limitations of (i) and (ii) imply, but are not limited to, the following:
- perimeter rim board/ledger resistance;
- higher loads/longer spans than the manufacturer’s pre-engineered details;
- concentrated loads;
- offset bearing walls;
- areas of high wind or high seismicity;
- stair openings;
- design of supporting wall studs/beams when the total load exceeds the NBC 2015 pre-engineered floor/roof joist tables; and
- design of supporting foundation footings when the total load exceeds the NBC 2015 pre-engineered floor/roof joist tables.
The engineer must design in accordance with CSA O86-14, “Engineering Design in Wood,” and may use the Canadian Wood Council’s “Engineering Guide for Wood Frame Construction” as a guide.
Additional installation details include:
- the assembly drawings must show the size of truss, the species and quality of the chord used, the product model number, and the relative location of the different truss types in the building assembly;
- the minimum end-bearing area must be 38 mm;
- the manufacturer’s instructions on required strongbacks and glued subfloor (adhesive conforming to CAN/CGSB-71.26-M88, “Adhesive for Field-Gluing Plywood to Lumber Framing for Floor Systems”) must be followed;
- notching or drilling of the wood chords is not allowed;
- the nailing pattern for the wood subfloor must conform to the NBC 2015; and
- ends of joists must be restrained to resist uplift and rollover. The top chord must be laterally supported at 600 mm on centre.
Fabrication of joists
The scope of this CCMC evaluation is the metal web product and the capacity of joists that may be fabricated by a third-party using these metal webs. When the product is used as floor joists, the truss fabrication details must be followed by the authorized truss fabricator. The fabrication instructions are contained in the document “Manufacturing the Posi-Strut® Metal Web Floor System,” dated October 1, 2018, and are to be used in conjunction with TPIC-2014, “Truss Design Procedures and Specifications for Light Metal Plate Connected Wood Trusses (Limit States Design),” published by the Truss Plate Institute of Canada (TPIC).
The AHJ must request conformity with respect to fabrication of the “Posi-Strut® Metal Web Joists” in the same manner as requested for light metal-plated roof trusses. The tooth-like projections of the metal webs must be fully pressed into both sides of the chords. The structural chords must be clearly grade-marked as S-P-F No. 2 or MSR grades and must contain less than 19% MC during the fabrication. Knots or wanes under the bearing point of the web plates are not permitted.
Engineering support provided by manufacturer
MiTek Canada Inc. provides engineering services in conjunction with “Posi-Strut® Metal Web Joists” specifications and offers the following support contact number for their Canadian offices:
MiTek Technical Support: 800-268-3434
The metal web components must be identified with “CCMC 12691-R” on the shipping box. In the field, the metal webs on the completed joists are identified by the joist depth/model identification (e.g., PS-10V2).
This evaluation is based on demonstrated conformance with the following criteria:
|Criteria number||Criteria name|
|CCMC-TG-061736-15||CCMC Technical Guide for Corrugated Metal Web|
The evaluation holder has submitted technical documentation for CCMC’s evaluation. Testing was conducted at laboratories recognized by CCMC. The corresponding technical evidence for this product is summarized below.
Factored shear resistances
|Product designation||Truss depth, mm (in.)||Maximum factored web shear, N (lbf.)|
|Compression webs||Tension webs|
|Single webTable footnote footnote (2)||Double webTable footnote footnote (2)||Single web||Double web|
|Posi-Strut® Metal Web Joist PS-10V2||235 (9 1/4)||4 181 (940)||5426 (1 220)||4 181 (940)||5 426 (1 220)|
|Posi-Strut® Metal Web Joist PS-12||286 (11 1/4)||4 657 (1 047)||5 484 (1 233)||5 142 (1 156)||5 787 (1 301)|
|Posi-Strut® Metal Web Joist PS-12i||302 (11 7/8)||4 644 (1 044)||5 141 (1 156)||5 084 (1 143)||5 822 (1 309)|
|Posi-Strut® Metal Web Joist PS-13||324 (12 3/4)||5 150 (1 158)||5 929 (1 333)||5 186 (1 166)||6 129 (1 378)|
|Posi-Strut® Metal Web Joist PS-14V3||356 (14)||4 804 (1 080)||6 138 (1 380)||4 804 (1 080)||6 138 (1 380)|
|Posi-Strut® Metal Web Joist PS-16V3||406 (16)||5 249 (1 180)||6 138 (1 380)||5 249 (1 180)||6 138 (1 380)|
|Product designation||Truss depth, mm (in.)||Deflection factor, α|
|Stiffness matrix methodTable footnote (1)||Factor beam methodTable footnote (2)|
|Posi-Strut® Metal Web Joist PS-10V2||235 (9 1/4)||1.263||1.431|
|Posi-Strut® Metal Web Joist PS-12||286 (11 1/4)||1.243||1.456|
|Posi-Strut® Metal Web Joist PS-12i||302 (11 7/8)||1.248||1.497|
|Posi-Strut® Metal Web Joist PS-13||324 (12 3/4)||1.248||1.497|
|Posi-Strut® Metal Web Joist PS-14V3||356 (14)||1.345||1.499|
|Posi-Strut® Metal Web Joist PS-16V3||406 (16)||1.338||1.517|
Additional test information
The design values obtained from testing to CCMC’s technical guide for “Posi-Strut® Metal Web Joists, following the principles in CAN/CSA-O86, are summarized below. The manufacturer’s published pre-engineered joist spans were designed in accordance with CAN/CSA-O86.
|Shear capacity||A multitude of shear specimens were tested for the target SG groups of S-P-F. A regression analysis was then conducted for ultimate loads versus the wood failure and metal failure modes. The characteristic values were then determined using standardized Coefficient of Variation (COV) for the failure modes. Reliability normalization factors were applied in accordance with CAN/CSA-O86 procedures to obtain limit states design shear resistance values.|
|Moment capacity||Determined analytically in accordance with engineering principles consistent with TPIC-2007 and CAN/CSA-O86.|
Stiffness capacity was tested to establish the deflection factor for a 1-h duration of the target live load of L/360. The following formula may be used to predict mid-span deflection:
⃤ = α ∗ (5wL4) / (384EI)
α = the deflection factor for the specific metal web truss using beam method and is calculated as the ratio of measured deflection from testing to calculated deflection based on beam model using the bending stiffness of the chords
w = uniform distributed service load
E = modulus of elasticity of the lumber chord
|End bearing length||The minimum end bearing is based on the maximum shear capacity or the compression perpendicular limitation of the chord or supporting bottom plate.|
|Creep||Full-scale 24-h creep and recovery tests were conducted for six (6) pairs of trusses. The truss designs tested were governed by serviceability, and moment capacity or shear capacity.|
|Metal web requirements||The metal webs are manufactured from galvanized sheet steel conforming to Grade 40 of ASTM A 653/A 653M. The placement of metal webs complies with Article 220.127.116.11 of CAN/CSA-O86. Minimum galvanizing must be G90 coating class.|
|Manufacturing quality assurance||Posi-Strut® Metal Web
The manufacture of the proprietary metal web is governed by MiTek Canada Inc.’s in-plant quality control manual administered by MiTek for the production of their proprietary metal products.
Posi-Strut® Metal Web Trusses/Joists
The manufacture of the finished floor trusses, as with the fabrication of roof trusses, is governed by the MiTek Canada Inc.’s truss fabrication quality assurance program administered by their licensees (truss fabricators).
Fire protection options
This section is beyond the scope of the CCMC's Code compliance opinion related to the evaluation of structural performance. The performance of the fire-protection options have been reviewed by the CCMC and are presented as additional information for AHJs.
Fire performance of innovative structural products
The CCMC Registry of Product Assessments contains opinions on the suitability-for-use of products intended as structural elements in houses. Although historically there has been no need to regulate the structural fire performance of houses, an inherent intent of the National Building Code of Canada (NBC) is that occupants have sufficient time to escape from a house in the event of a fire. There are many factors that may determine whether that intent is achieved. The fire endurance of structural elements may be one. However, its importance may be minimized by other factors such as combustible content load, early warning devices, smoke movement and toxicity, and fire department response time; all contributing to the overall system performance. Research is underway within the NRC Construction Research Centre to determine the critical factors that affect occupant escape from houses.
Some innovative structural products have been used in the marketplace for several years and have gained the confidence of design professionals, code authorities and users with respect to their performance under typical fire scenarios. Some newer products have not been in service long enough to have gained that confidence and may present a more obvious concern.
The minimum fire performance of innovative structural materials, or alternative solutions, as compared to that of the NBC-specified conventional wood-frame construction, or acceptable solution, has been the subject of analysis and discussion for several years among fire officials, provincial and territorial regulators, and AHJs. In fire testsFootnote (2) conducted between 2002 and 2008 at NRC, the innovative structural joist systems tested, and currently in the marketplace (i.e., I-joists, C-channel steel joists, metal-plated wood trusses and metal-web trusses), had a time-to-collapse below the performance of exposed 38 mm × 235 mm (2 × 10) lumber joists.
The CCMC provides this floor fire performance information to the local AHJs across Canada to aid their decision-making on whether the fire performance of floors (i.e., the time to evacuate before failure occurs) for alternative joist systems performs “as well as” the inherent fire performance of exposed 38 mm × 235 mm (2 × 10) lumber joists. As is the case for all innovative products, designers and authorities should exercise judgment in considering the use of innovative structural products for houses. Unless otherwise stated, innovative structural products for houses have not been evaluated in the context of the NBC intent noted above.
Fire performance data submitted by the evaluation holderThe engineered joist manufacturer (evaluation holder) submitted fire-protection options for its proprietary joist system when used in single-family houses (unsprinklered).The fire-protection options follow the principles in Appendix D of Division B of the NBC.
Proposed fire protection options
The manufacturer’s fire protection options for its proprietary joists is presented in below. The CCMC has reviewed this fire-protection option in comparison to the fire performance of unprotected exposed 38 mm × 235 mm (2 × 10) floor joist system.Footnote (1) The proposed fire-protection option performs “as well as” exposed 38 mm × 235 mm (2 × 10) lumber joists. It should be noted that the NBC exempts single-family houses constructed using conventional wood-frame construction, in accordance with Part 9, from requiring a fire-resistance rating (see Article 18.104.22.168. of Division B of the NBC 2015). The proposed fire-protection option for proprietary alternative floor joists is not to be considered in sprinklered single-family houses or where fire-resistance-rated assemblies are required.
Posi-strut® Metal Web Joists fire protection optionThe floor assembly shown below is the default alternative assembly for all cases and where the manufacturer has not undertaken any specific fire testing to show that the product performs “as well as” exposed 38 mm × 235 mm (2 × 10) lumber with a specific joist fire-protection option.
Use of Canadian Construction Materials Centre (CCMC) assessments
This assessment must be read in the context of the entire CCMC Registry of Product Assessments, any applicable building code or by-law requirements, and/or any other regulatory requirements (for example, the Canada Consumer Product Safety Act, the Canadian Environmental Protection Act, etc.).
It is the responsibility of the user to confirm that the assessment they are using is current and has not been withdrawn or superseded by a later version on the CCMC Registry of Product Assessments.
The National Research Council of Canada (NRC) has evaluated only the characteristics of the specific product described herein. The information and opinions in this evaluation are directed to those who have the appropriate degree of experience to use and apply its contents (such as authorities having jurisdiction, design professionals and specifiers). This evaluation is valid when the product is used as part of permitted construction, respecting all conditions and limitations stated in the evaluation, and in accordance with applicable building codes and by-laws.
This evaluation is provided without representation, warranty or guarantee of any kind, expressed or implied, and the NRC provides no endorsement for any evaluated product. The NRC accepts no responsibility whatsoever arising in any way from any and all use of or reliance on the information contained herein or the use of any evaluated product. The NRC is not undertaking to render professional or other services on behalf of any person or entity nor to perform any duty owed by any person or entity to another person or entity.
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© His Majesty the King in Right of Canada, as represented by the National Research Council of Canada, 2023
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the CCMC.