Advanced industrialized construction methods enable complex building components and systems to be built with high precision and quality. This manufacturing technique has an advantage to provide cost-competitive and high energy efficient building components and systems for both retrofits and new construction. This document gives an overview of the use of prefabricated panels in building Net Zero Energy Ready wood-frame multi-unit residential buildings (MURBs) in Edmonton.
Timber has been used for building construction for centuries, until the industrial revolution, when it was often replaced by steel and concrete or confined to low-rise housings. In the last thirty years however, thanks to the development of mass timber products and new global interest in sustainability, timber has begun to make a resurgence in the building industry. As building codes and public perception continues to change, the demand for taller and higher-performance timber buildings will only grow. Thus, a need exists for new construction technology appropriate for taller mass timber construction, as well as for fabrication and deconstruction practices that respect wood’s inherent sustainable nature. With this in mind, this research program aims to develop a new hybrid shear connection for mass timber buildings that allows for easy construction, deconstruction, and reuse of the structural elements.
This report includes results of Phase 1, which focused on connections consisting of partially threaded 20M and 24M steel rods bonded into pockets formed in CLT and surrounded by thick crowns of high-strength three-component epoxy-based grout. A total of 168 specimens were designed and fabricated, and push-out shear tests carried out with a displacement-controlled monotonic loading protocol. Strength and stiffness values were assessed and effective failure modes in specimens identified. These latter, along with the recorded load-deformation curves, indicate that it is possible to develop mechanics-based design models and design formulas akin to those already used for typical dowel-type fastener timber connections. Additionally, the specimens were easily fabricated in the lab and quickly fastened to the test jig by means of nuts and washers, suggested such connections have a strong potential for prefabrication, disassembly, and reuse.
This project identifies drivers for, and barriers to, the increased use of prefabricated timber building (PTB) systems in Class 2 to 9 commercial buildings, such as apartments, hotels, office buildings and schools.
PTB systems in Australia are in a formative stage and yet to achieve broad acceptance in the marketplace as a conventional method of building.
Opportunities for PTB systems can use timber’s well-established benefits such as high strength-to-weight ratio; design and construction flexibility; general environmental credentials including carbon sequestration; and prefabrication’s suitability for use on brown-field, restricted access and difficult sites and developments. In addition legislative constraints have now been largely removed (e.g. through changes to the 2016 National Construction Code).
An increase in large scale mid-rise prefabricated buildings, and with the increasing nationalisation and internationalisation of the top tier building companies, suggests market acceptance will grow as PTB buildings are seen as ‘normal’.
This project evaluates off-site solid timber production processes in the international solid timber industry. The Solid Timber Construction (STC) projects documented herein provide a test bed to evaluate project performance metrics attributed to off-site construction. This study also evaluates the contingent qualitative environmental, organizational and technological contextual factors related to STC. The study therefore:
Investigates and documents STC projects to identify successful performance metric parameters: economics, schedule, scope, quality, risk, and worker safety.
Compares this data to traditional site built construction to determine the estimated added value or negative impact of STC.
Identifies qualitative contextual parameters including environment, organization and technology for successfully developing STC methods;
Creates a model for data gathering for STC stakeholders to report their own performance parameters and thereby create a robust database of off-site projects in the future.
Synthesizes holistic best processes and practices guide for the industry looking to engage in STC work.
Across B.C. and Canada, communities are under pressure to create better-performing buildings that meet stringent code requirements while reducing construction waste. Meanwhile, consumers are demanding high-quality structures that are delivered quickly and at a reasonable price. Modern methods of construction that include prefabrication can help construction professionals create buildings that meet all these criteria.
Furthermore, prefabrication provides steady employment and is good for the economy. The market opportunities are present across Canada and in the U.S., but prefabrication is not being used to its potential due to several barriers:
Negative perception of quality
Fear of innovation
Lack of information and understanding
Unclear economic benefits
Limited industry capacity
Planning and regulatory complications
A concerted effort to address these barriers includes:
Improving products through research and development
Researching, documenting, and promoting best practices
Developing guidance documents so prefabrication is easier to incorporate
Providing national-level leadership and resources to promote innovation
Successfully implementing these recommendations will require a broad and deep national perspective, an understanding of all stages and aspects of wood construction, and the vision and skills to bring together diverse experts and stakeholders.
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