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Cross-laminated timber (CLT) is a proprietary engineered wood product that is prefabricated using several layers of kiln-dried lumber, laid flat-wise, and glued together on their wide faces. Panels typically consist of three, five, seven or nine alternating layers of dimension lumber. The alternating directions of the CLT laminations provide it with high dimensional stability. CLT also has a high strength to weight ratio, along with exhibiting advantages for structural, fire, thermal and acoustic performance. Panel thicknesses usually range between 100 to 300 mm (4 to 12 in), but panels as thick as 500 mm (20 in) can be produced. Panel sizes range from 1.2 to 3 m (4 to 10 ft) in width and 5 to 19.5 m (16 to 64 ft) in length. The maximum panel size is limited by the size of the manufacturer’s press and transportation regulations. The design provisions for CLT in Canada apply to sawn lumber panels manufactured in accordance with the ANSI/APA PRG 320 standard. Typically, all the laminations in one direction are manufactured using the same grade and species of lumber. However, adjacent layers are permitted to be of different thickness and made of alternative grades or species. The moisture content of the lumber laminations at the time of CLT manufacturing is between 9 and 15%. There are five primary CLT stress grades; E1, E2, E3, V1 and V2. Stress grade E1 is the most readily available stress grade. The “E” designation indicates machine stress rated (MSR, or E-rated) lumber and the “V” designation indicates visually graded lumber. Stress grades E1, E2 and E3 consist of MSR lumber in all longitudinal layers and visually graded lumber in the transverse layers, while stress grades V1 and V2 consist of visually graded lumber in both longitudinal and transverse layers. Properties for custom CLT stress grades are also published by individual manufacturers. Similar to other proprietary structural wood products, CLT can be evaluated by the Canadian Construction Materials Centre (CCMC) in order to produce a product evaluation report. Unlike primary and custom CLT stress grades which are associated with structural capacity, appearance grades refer to the surface finish of CLT panels. Any stress grade can usually be produced in any surface finish targeted by the designer. Accommodations for reductions in strength and stiffness due to panel profiling or other face- or edge-finishes must be made. The Appendix of ANSI/APA PRG 320 provides examples of CLT appearance classifications. Structural adhesives used in bonding laminations must comply with CSA O112.10 and ASTM D7247 and are also evaluated for heat performance during exposure to fire. The different classes of structural adhesives that are typically used include: Emulsion polymer isocyanate (EPI); One-component polyurethane (PUR); Phenolic types such as phenol-resorcinol formaldehyde (PRF). Since pressure treatment with water-borne preservatives can negatively affect bond adhesion, CLT is not permitted to be treated with water-borne preservatives after gluing. For CLT treated with fire-retardant or other potentially strength-reducing chemicals, strength and stiffness is required to be based on documented test results. As part of the prefabrication process, CLT panels are cut to size, including door and window openings, with state-of-the art computer numerical controlled (CNC) routers, capable of making complex cuts with low tolerances. Prefabricated CLT elements arrive on site ready for immediate installation. CLT offers design flexibility and low environmental impacts for floor, roof and wall elements within innovative mid-rise and tall wood buildings. For further information on CLT, refer to the following resources: Kalesnikoff Nordic Structures APA – The Engineered Wood Association Canadian Construction Materials Centre (CCMC) Element5 ANSI/APA PRG 320 Standard for Performance-Rated Cross-Laminated Timber CSA O86 Engineering design in wood CSA O112.10 Evaluation of Adhesives for Structural Wood Products (Limited Moisture Exposure) ASTM D7247 Standard Test Method for Evaluating the Shear Strength of Adhesive Bonds in Laminated Wood Products at Elevated Temperatures

The effects of a single opening size and location on diaphragm shear, chord forces and framing member forces were investigated for a typical wood diaphragm. In conclusion, the maximum shear in the diaphragm with opening is greater than that in the diaphragm without opening. Increasing the distance between the edges of opening and diaphragm can reduce this increase in maximum shear significantly. When the dimension of the opening is no greater than 15% of the corresponding dimension of the diaphragm in both directions, and the distance of opening edge from diaphragm edge is no less than 3 times the larger dimension of the opening and that the portion of diaphragm alongside the opening satisfies the maximum aspect ratio requirement, the increase in maximum shear is less than 10%.

This Rothoblaas document explores the role of underfloor insulation in improving acoustic performance in long-span cross-laminated timber (CLT) floor systems. Intended for designers, engineers, and building professionals, the document addresses key soundproofing challenges associated with larger spans and exposed timber structures. The document explains how underfloor insulation contributes to reducing airborne and impact sound transmission, with discussion of system behaviour, material selection, and integration with CLT floor assemblies. It also highlights design and construction considerations that influence acoustic performance, including detailing, installation quality, and coordination with other building systems. Developed as a technical reference, this document supports informed design decisions for long-span CLT floors, helping project teams achieve acoustic comfort while maintaining structural and architectural objectives.

GHL CONSULTANTS LTD (GHL) has witnessed the testing of firestop systems installed within CLT assemblies to CAN/ULC-S115 2011 at Intertek Laboratories in Coquitlam on February 15 to 17, 2016. This report is supplemental to the attached test report in Appendix A produced by Intertek and serves four purposes: To confirm that we witnessed the tests noted. To provide our observations in addition to those recorded by Intertek. To identify some reliable and sound interpolations of the data to support firestop judgments. To identify, based on these tests and other tests of CLT assemblies (also included as appendices) witnessed by our office, some clear concepts that assist in application of the data to joint configurations. The testing performed by Intertek on February 15 to 17 consisted of horizontal through penetrations within CLT floor assemblies being exposed to the standardized time temperature curve of CAN/ULC S101. The through penetrations tested were of cast iron, schedule 40, copper and plastic pipes, bundled cables and a drop in Hilti firestop device

This testing program was carried out by the Advanced Building Systems (ABS) Department of FPInnovations in response to a request made by Mrs. Julie Frappier of Nordic Engineered Wood and Mr. Étienne Lalonde of Canadian Wood Council (CWC) for the evaluation of the shear stress resistance of one hundred fifty two (152) cross-laminated timber (CLT) beams. All specimens were manufactured by Nordic Engineered Wood and delivered to FPInnovations’ testing facilities in Québec City. The main objective of this study was to evaluate the in-plane shear stress of CLT depending of its orientation and the number of plies. Specific Gravity and Moisture Content measurements were also determined for each specimen.

A testing program related to the evaluation of the mechanical properties of CLT diaphragms used in construction was carried out by the Advanced Building Systems (ABS) Department of FPInnovations in response to a request made by the Client, Nordic Engineered Wood Products. The main objective of this study was to determine the in-plane stiffness and potentially strength properties of CLT panels used in diaphragm applications. The test matrix consisted of three (3) series of two (2) specimens each. The CLT specimens were tested under third-point loading during the program. All specimens were manufactured by Nordic Engineered Wood Products and delivered to FPInnovations’ testing facilities in Québec City. The CLT panels were made of nominal 2×4 Black Spruce lumber (CLT Grade E1 – ANSI PRG 320).

A testing program was carried out by the Advanced Building Systems (ABS) Department of FPInnovations in response to a request made by Mrs. Julie Frappier of Nordic Engineered Wood Products for the evaluation of the effective shear modulus of eight (8) different Cross-laminated Timber (CLT) configurations or series. The test matrix consisted of a total seventy (70) specimens and each specimen was submitted to four (4) bending tests, resulting in a total two hundred and eighty (280) tests. All specimens were manufactured by Nordic Engineered Wood Products and delivered to FPInnovations’ testing facilities in Québec City.

This testing program was carried out by the Advanced Building Systems (ABS) Department of FPInnovations in response to a request from Mrs. Julie Frappier from Nordic Engineered Wood for the evaluation of the mechanical properties of three (3) different assemblies for attaching Cross Laminated Timber (CLT) panels. Each of the assemblies consisted of six (6) specimens for a total of eighteen (18) tests. All specimens were manufactured by Nordic Engineered Wood and delivered to FPInnovations’ laboratory in Québec City. The key objective was to evaluate the mechanical properties pertinent for the design of CLT panel connections exposed to in-plane loading such as diaphragms or shear walls. The evaluation of the ultimate loading capacity (𝐏𝐮𝐥𝐭) and the stiffness (K) of the connections are thus the main focus of this study.

This report describes a full-scale exterior wall fire test conducted on December 16, 2014 on a Nordic cross-laminated timber (CLT) wall system. The test was conducted in accordance with CAN/ULC-S134-13, Standard Method of Fire Test of Exterior Wall Assemblies.