Since the publication of the first edition of this guide, substantial regulatory changes have been implemented in the 2020 edition of the National Building Code of Canada: the addition of encapsulated mass timber construction up to 12 storeys, and the early adoption of the related provisions by several provinces are the most notable ones. The 2022 edition of this guide brings together, under one cover, the experience gained from recently built tall wood projects, highlights from the most recent building codes and standards, and research findings to help achieve the best environmental, structural, fire, and durability performance of mass timber products and systems, including their health benefits. The approaches to maximizing the benefits of prefabrication and building information modelling, which collectively result in fast, clean, and quiet project delivery, are discussed. Methods for addressing limitations controlled by fire requirements (through an Alternative Solution) or seismic requirements (through a hybrid solution using an Acceptable Solution in steel or concrete) are included. How best to build with mass timber to meet the higher performance requirements of the Energy Step Codes is also discussed. What makes building in wood a positive contribution toward tackling climate change is discussed so that design teams, in collaboration with building owners, can take the steps necessary to meet either regulatory or market requirements.
Midply shear wall, which was originally developed by researchers at Forintek Canada Corp. (predecessor of FPInnovations) and the University of British Columbia, is a high-capacity wood-frame shear wall system that is suitable for high wind and seismic loadings. Its superior seismic performance was demonstrated in a full-scale earthquake simulation test of a 6-storey wood-frame building in Japan (Peietal.,2010). Midply shear wall, however, had limited applications due to its low resistance to vertical load and difficulty to accommodate electrical and plumbing services. For broader applications of Midply shearwall, these limitations needed to be addressed.
In collaboration with APA–The Engineered Wood Association and the American Wood Council (AWC), a new framing arrangement was designed to increase the vertical load resistance of Midply shearwalls and make it easier to accommodate electrical and plumbing services. Consequently, structural, fire and acoustic tests have been conducted to evaluate various performance attributes of Midply shear wall with the new framing configuration. This InfoNote provides a summary of the structural, fire and acoustic performance of Midply shearwalls from the tests.
Light-frame wood structures are the most common type of construction for residential and low-rise buildings in North America. The 2015 edition of the National Building Code of Canada has increased the height limit for light-frame wood construction from 4 to 6 stories. With the increase in building height, it was noticed that light-frame wood structures may be governed by inter-story drift under wind and seismic loads. To reduce the inter-story drift, a hybrid system, consisting of CLT cores and light-frame structures, is proposed. The efficiency of this hybrid system is dependent on the performance of the connections between the two sub-systems. In this project, self-tapping screws (STSs) were used to connect the CLT core and light-frame wood structures on the floor level. Monotonic and reversed-cyclic tests were carried out on CLT-wood frame connections connected with STSs inserted at 45°, 90°, and mixed angles (45° and 90°). The connection performance was evaluated in terms of strength, stiffness, ultimate displacement, ductility, and energy dissipation capacity. Results show that a joint with STSs inserted at 45° had high stiffness and ductility but low energy dissipation, while connections with STSs installed at 90° had high ductility and energy dissipation but low stiffness. Connections with STSs inserted at mixed angles (45° and 90°) achieved the advantages of both configurations when the STSs were inserted at 45° or 90° individually, i.e., high stiffness, ductility, and energy dissipation. The ductility and energy dissipation were significantly improved compared with connections with STSs only inserted at 45° or 90°. This mixed angle connection can be an ideal design for connecting light-frame wood structures to a CLT core to resist wind and seismic load.
Due to the awareness of the importance of reducing environmental footprint and the rising costs of construction, timber structures have been increasingly attracting attention and, subsequently, adoption for being built taller and larger. Computer modelling plays a crucial role in the analysis and design of large and tall timber structures, and in the development of wood-based products, connections, and systems. A survey by FPInnovations showed that practising engineers are typically unfamiliar with timber structure modelling, and researchers generally lack resources for advanced modelling of timber systems. Therefore, in 2020, FPInnovations initiated a project to develop a guide that would support the application of numerical modelling on the analysis and design of timber structures, and the development and optimisation of wood-based products and systems. The Modelling Guide for Timber Structures is the result of a global effort involving over 100 collaborators, including experts from research institutes, consulting firms, manufacturers, software companies, government entities, and associations.
This guide brings together the experience gained from recently built timber projects, and the latest research development in the modelling of timber structures. It includes a wide range of practical and advanced modelling topics, such as key modelling principles, methods, and techniques specific to timber structures; modelling approaches and considerations for wood-based components, connections, and assemblies; and analytical approaches and considerations for timber structures during progressive collapse, wind, and earthquake events. It also presents the differences in the modelling approaches to timber, steel, and concrete structures.
The information presented in this guide is intended to assist practising engineers to apply computer modelling to timber structures, enrich researchers’ resources for advanced computer modelling of timber systems, and assist software companies in identifying knowledge gaps so that they may upgrade programs accordingly to accommodate the advanced computer modelling of timber structures.
The overall objective of this study is to provide information to building design practitioners that will help to improve accuracy of hygrothermal models and enable them to better use these models to predict the durability and thermal performance of wood-based building envelopes. To achieve this, hygrothermal models using WUFI Pro software are validated with experimental data obtained from five wood-frame wall assemblies, with different insulation and vapour control strategies, exposed to the climatic conditions of Vancouver from October 2018 to May 2020. This exercise provides a set of model input parameters that the practitioner can use to assess similar structures exposed to similar environmental conditions. Sensitivity analysis is conducted on the model input parameters to establish which are the most important in obtaining a good fit to experimental measurements, and therefore accurate prediction of assembly performance. There is also discussion on limitations of the hygrothermal model.
This InfoNote summarizes the verification and validation that the current design requirements of Annex B of CSA O86 can also be applied to small framing members used in unprotected and protected lightweight wood-frame assemblies, e.g., walls and floors. With minor editorial changes, the scope of application of Annex B of CSA O86 could include all wood and wood-based products listed in CSA O86, regardless of their original and residual dimensions.
Glued Laminated Timber, commonly referred to as Glulam, is an important structural wood product, suitable for use in exterior applications provided it is protected against decay by building design, natural durability, or treatment. Bonding treated lamina made from refractory species is challenging because resurfacing after treatment can remove much of the treated zone and create a waste disposal challenge. It was hypothesized that use of roll-pressing rather than resurfacing could address this. When an adhesive modifier was used to prevent the adverse effects of wood preservatives on adhesive bonding, treated lamina that were replaned before gluing had similar shear strength to untreated planed lamina. However, the treated lamina that were roll-pressed before gluing had lower shear strength than the replaned lamina. The consequence of this weakening was evident in an above-ground field test where delamination was observed in several test units after 12 years of exposure. Decay resistance was evaluated in above-ground, ground contact, and ground proximity tests. The decay resistance of treated glulam was high with only low levels of decay reported in all tests, while untreated controls showed advanced decay or failure. Yellow cedar glulam, included as a reference in the ground proximity test, showed moderate decay after 10 years of exposure.
This new study aims to generate hygrothermal, particularly moisture-related performance data for light wood-frame walls meeting the R22 effective (RSI 3.85) requirement for buildings up to six storeys in the City of Vancouver. The overarching goal is to identify and develop durable exterior wood-frame walls to assist in the design and construction of energy efficient buildings across the country. Twelve test wall panels in six types of wall assemblies are assessed in this study. The wall panels, each measuring 4 ft. (1200 mm) wide and 8 ft. (2400 mm) tall, form portions of the exterior walls of a test hut located in the rear yard of FPInnovations’ Vancouver laboratory. This report, second in a series on this study, documents the performance of these wall assemblies based on the data collected over 19 months’ period from October 2018 to May 2020, covering two winter seasons and one summer.
A test program was conducted to generate hygrothermal performance data for light-wood-frame exterior walls meeting the R22 effective (RSI 3.85) requirement for buildings up to six storeys in the City of Vancouver. Six types of exterior wall assemblies, with 12 wall panels in total, were tested using a test hut located in the rear yard of FPInnovations’ Vancouver aboratory. This document provides a brief summary of the test and performance of these walls based on the data collected over the 19 months’ period from October 2018 to May 2020
Un programme d’essais a été réalisé en vue de générer des données sur le rendement hygrothermique des murs à ossature légère de bois qui répondent à l’exigence R22 (RSI 3,85) pour les bâtiments d'au plus six étages à Vancouver. Six types d’assemblage de mur extérieur, avec un total de 12 murs extérieurs, ont été mis à l’essai à l’aide d’une hutte d’essai située dans la cour arrière du laboratoire de FPInnovations à Vancouver. Le présent document présente un court résumé de l’essai et du rendement de ces murs en se basant sur les données recueillies sur une période de 19 mois, soit d’octobre 2018 à mai 2020 (Wang 2021).