As part of its research work on wood buildings, FPInnovations has recently launched a Design Guide for Timber-Concrete Composite Floors in Canada. This technique, far from being new, could prove to be a cost-competitive solution for floors with longer-span since the mechanical properties of the two materials act in complementarity. Timber-concrete systems consist of two distinct layers, a timber layer and a concrete layer (on top), joined together by shear connectors. The properties of both materials are then better exploited since tension forces from bending are mainly resisted by the timber, while compression forces from bending are resisted by the concrete. This guide, which contains numerous illustrations and formulas to help users better plan their projects, addresses many aspects of the design of timber-concrete composite floors, for example shear connection systems, ultimate limit state design, vibration and fire resistance of floors, and much more.
The CLT Handbook provides vital “How to” information on CLT for the design and construction community, and is a great source of information for regulatory authorities, fire services and others. The CLT Handbook is also a good textbook for university level timber engineering courses. In summary, the Canadian CLT Handbook will remain the most comprehensive reference for sharing the latest technical information on North American CLT.
The Canadian edition of the CLT Handbook, first published in 2011 under the Transformative Technologies Program of the Natural Resources Canada, played an imperative role in accelerating the use and acceptance of CLT in North America. Its introduction subsequently led to the publication of the US Edition. The Canadian Edition supported the early use of CLT products from Canadian manufacturers in many small to large projects across Canada and the US, and paved the way for CLT and other wood products to be used in new applications like tall and large buildings, and bridges.
Since then, additional research has taken place globally and substantial regulatory changes have occurred enabling more wood to be used in construction. Those developments highlighted a need for the CLT Handbook to be updated. The 2019 Edition of the CLT Handbook, for example, augments the recently developed CLT provisions in CSA Standard in Engineering Design in Wood and it includes a design example of an 8-storey CLT building. It helps expand the knowledge base of the designers about CLT enabling them to develop alternative solutions for taller and larger buildings that are beyond the boundaries of the acceptable solutions in building codes.
Mass timber and CLT construction offers many advantages, such as enhanced modularity, reduced construction schedules, improved thermal performance, and material sustainability. However, mass timber’s propensity to absorb moisture from the environment and the relative vapor impermeability of CLT panels introduces unique challenges when incorporated with the building enclosure. These challenges should be considered during design and construction phases to ensure long-term performance.
The VaproShield Mass Timber Building Enclosure Design Guideline covers the best practices for the design and construction of high-performance CLT wall and roof assemblies. RDH is the principal author and editor of the guide and within its capacity, we do not purport to endorse any specific material or technical matter within this guide.
This Illustrated Guide consolidates information on vaulted water-shedding roofs and flat waterproof membrane roofs that are capable of meeting R-30 or greater effective thermal performance when used on low- and mid-rise wood-frame buildings. The guide is intended to be an industry, utility, and government resource with respect to meeting this thermal performance level, while not compromising other aspects of building enclosure performance, including moisture management, air leakage, and durability.
The purpose of this guide is to provide an introduction to the concept of encapsulated mass timber construction. This guide provides an overview of encapsulation techniques for mass timber construction, and other related fire protection measures, and summarizes some approved encapsulation materials and application methods and identifies additional requirements for safety during construction. This guide is intended to help architects, engineers and designers by reducing uncertainty and allowing for more confidence in design, as well as providing authorities having jurisdiction and inspectors with a reference for simple design review.
In recent years, the science and engineering for controlling sound transmission in buildings have shifted from a focus on individual assemblies such as walls or floors, to a focus on performance of the complete system. Standardized procedures for calculating the overall transmission, combined with standardized measurements to characterize sub-assemblies, provide much better prediction of sound transmission between adjacent indoor spaces. The International Standards Organization (ISO) has published a calculation method, ISO 15712-1 that uses laboratory test data for sub-assemblies such as walls and floors as inputs for a detailed procedure to calculate the expected sound transmission between adjacent rooms in a building. This standard works very well for some types of construction, but to use it in a North American context one must overcome two obstacles – incompatibility with the ASTM standards used by our construction industry, and low accuracy of its predictions for lightweight wood or steel frame construction. To bypass limitations of ISO 15712-1, this Guide explains how to merge ASTM and ISO test data in the ISO calculation procedure, and provides recommendations for applying extended measurement and calculation procedures for specific common types of construction. This Guide was developed in a project established by the National Research Council of Canada to support the transition of construction industry practice to using apparent sound transmission class (ASTC) for sound control objectives in the National Building Code of Canada (NBCC). However, the potential range of application goes beyond the minimum requirements of the NBCC – the Guide also facilitates design to provide enhanced sound insulation, and should be generally applicable to construction in both Canada and the USA. This publication contains a limited set of examples for several types of construction, to provide an introduction and overview of the ASTC calculation procedure. Additional examples and measurement data can be found in the companion documents to this Guide, namely NRC Research Reports RR-333 to RR-337. Furthermore, the calculation procedure outlined and illustrated in this Guide is also used by the software web application soundPATHS, which is available for free on the website of the National Research Council of Canada (see the references in Section 7 of this Guide for access details).
This Design and Construction Guide (the Guide) provides the U.S. design and construction community with guidance to ensure safe, predictable, and economical use of NLT. It is intended to offer practical strategies, advice, and guidance, transferring knowledge and lessons learned from NLT project experience.
This Guide focuses on design and construction considerations for floor and roof systems pertaining to U.S. construction practice and standards. While NLT is being used for vertical elements for walls, stair shafts, and elevator shafts, this Guide provides the greatest depth of direction for more common horizontal applications. The information included here is supplemental to wood design and construction best practices and is specific to the application of NLT. Built examples are included to illustrate real application and visual reference as much as possible.
This Design and Construction Guide (the Guide) provides the Canadian design and construction industry with immediate support and guidance to ensure safe, predictable, and economical use of NLT. It is intended to offer practical strategies, advice, and guidance, transferring knowledge and lessons learned from those with experience.
This Guide focuses on design and construction considerations for floor and roof systems pertaining to current Canadian construction practice and standards. While NLT is being used for vertical elements for walls, stair shafts, and elevator shafts, this Guide provides the greatest depth of direction for common horizontal applications. The information included here is supplemental to wood design and construction best practices and is specific to the application of NLT. Built examples are included to illustrate real application and visual reference as much as possible.
Overall moisture management during construction has become increasingly important due to the increase in building height and area, which potentially prolongs the exposure to inclement weather, and the overall increase in speed of construction, which may not allow adequate time for drying to occur. This report provides guidelines and relevant information about on-site moisture management practices that can be adapted to suit a range of wood construction projects...
Building tall in wood is not a new phenomenon. In fact, Canada has a history of constructing tall wood buildings out of heavy timber and brick elements, reaching up to nine storeys. In the early 20th century, with the increase in reinforced concrete and structural steel research and construction, and with growing concerns over fire and durability, the structural use of wood fell out of common use in tall buildings. This trend is beginning to reverse, however. In the last few decades, the world has seen a resurgence of mass timber products and systems that are paving the way for tall wood buildings. This triggered an initiative by Natural Resources Canada (NRCan) to support tall wood building demonstration projects to enhance Canada’s position as a global leader in wood building construction, by showcasing the application and performance of advanced wood technologies. The Technical Guide for the Design and Construction of Tall Wood Buildings in Canada has been prepared to assist architects, engineers, code consultants, developers, building owners, and Authorities Having Jurisdiction (AHJ) in understanding the unique issues to be addressed when developing and constructing tall wood buildings.
Cross-laminated timber (CLT), a new generation of engineered wood product developed initially in Europe, has been gaining increased popularity in residential and non-residential applications in several countries. Many impressive low- and mid-rise buildings built around the world using CLT showcase the many advantages this product has to offer to the construction sector. In this Chapter, we put forward an introduction to CLT as a product and CLT construction in general, along with different examples of buildings and other structures made with CLT panels. CLT is now available in North America and several projects already built in Canada and the United States, using CLT, are presented in this Chapter. An assessment of market opportunity for CLT based on the latest construction statistics for the United States is also presented.
This Chapter provides general information about the manufacturing of CLT that may be of interest to the design community. The information contained in this Chapter may also provide guidance to CLT manufacturers in the development of their plant operating specification document. Typical steps of the CLT manufacturing process are described, and key process variables affecting adhesive bond quality of CLT products are discussed. The manufacturing, qualification, and quality assurance requirements in accordance with the American National Standard for Performance-Rated Cross-Laminated Timber, ANSI/APA PRG 320, are discussed.
Building using cross-laminated timber (CLT) began in Europe about two decades ago and has used a variety of methods for structural analysis. Experimental testing methods were the most accurate, yet they lacked versatility because changes in lay-up, material, or even manufacturing methods could cause a need for new testing. Consequently, three analytical approaches have been created and are commonly used in Europe as none have been universally accepted to date. ... In the United States and Canada, the product standard (Standard for Performance-Rated Cross-Laminated Timber - ANSI/APA PRG 320) has adopted the Shear Analogy method to derive composite bending and shear stiffness properties.
Cross-laminated timber (CLT) is an innovative wood product that was developed approximately two decades ago in Europe and has since been gaining in popularity. Based on the experience of European researchers and designers, it is believed that CLT can provide the U.S. market the opportunity to build mid- and high-rise wood buildings. This Chapter presents a summary of past research and state-of-the-art understanding of the seismic behavior of CLT. As a new structural system to the United States, the design of CLT for seismic applications is expected to be made through alternative method provisions of the building codes. Efforts to develop seismic design coefficients for use in the equivalent lateral force procedures in the United States are underway. Nonlinear numerical modeling of CLT is presented and used to provide and indication of the effect of designing with different R-factors. Using nominal CLT wall capacity values derived from isolated wall tests, the illustrative example showed that an R-factor of approximately 2 can result in a low probability of collapse (less than 10 percent) at MCE intensity.
This Chapter focuses on a few fastening systems that reflect present-day practices, some being conventional, while others are proprietary. Given the recent introduction of CLT into the construction market, it is expected that new connection types will be developed over time. Issues associated with connection design specific to CLT assemblies are presented. The European design approach is also presented and the applicability of the National Design Specification (NDS) for Wood Construction design provisions for traditional fasteners in CLT such as bolts, dowels, nails, and wood screws are reviewed and design guidelines are provided. Several design examples are also given at the end to demonstrate how connections in CLT can be established using current NDS design provisions.
Cross-laminated timber (CLT) products are used as load-carrying slab and wall elements in structural systems, thus load duration and creep behavior are critical characteristics that must be addressed in structural design. Given its lay-up construction with orthogonal arrangement of layers bonded with structural adhesive, CLT is more prone to time-dependent deformations under load (creep) than other engineered wood products such as structural glued-laminated timber. Time dependent behavior of structural wood products is addressed in design standards by load duration factors that adjust design properties. Since CLT has been recently introduced into the North American market, the current design standards and building codes do not specify load duration and creep adjustment factors for CLT. Until this can be rectified, an approach is proposed in this Chapter for adopter of CLT systems in the United States. This includes not only load duration and service factors, but also an approach to accounting for creep in CLT structural elements.