Cross-Laminated Timber (CLT) is an innovative structural system based on the use of large-format, multilayered panels made from solid wood boards glued together, and layers at 90 degrees. This cross-laminated configuration translates into panels that are monolithic, stable, and experience minor shrinkage, which allows them to be used for the...
As the construction industry shifts towards sustainability and owners seek to construct buildings that are sustainable - built from natural and renewable materials, and pleasing for their occupants to work in - mass timber is becoming the popular alternative to traditional steel and concrete buildings. An abundance of information is available on mass timber products and their properties and applications, but little information on the process of actually building a mass timber project. This report seeks to extend practical knowledge on building with mass timber. In order to accomplish this, this research will highlight specific differences and challenges related to building with mass timber; create general guidelines and recommendations for contractors tasked with building a mass timber project; and identify new areas of research. Through interviews with two commercial contractors who have built mass timber projects in the California Bay Area, specific challenges have been identified. These challenges include longer project duration; increased preconstruction time and complexity; difficulties getting timely plan approvals; differing design and material procurement methods; necessity of MEP coordination at the beginning of the jobs; unique transportation, storage, and handling requirements; and different installation procedures and requirements.
Mass timber construction in Canada is in the spotlight and emerging as a sustainable building system that offers an opportunity to optimize the value of every tree harvested and to revitalize a declining forest industry, while providing climate mitigation solutions. Little research has been conducted, however, to identify the mass timber research priorities of end users, barriers to adoption and engineering, procurement and construction challenges in Canada. This study helps bridge these gaps. The study also created an interactive, three-dimensional GIS map displaying mass timber projects across North America, as an attempt to offer a helpful tool to practitioners, researchers and students, and fill a gap in existing knowledge sharing. The study findings, based on a web-based survey of mass timber end users, suggest the need for more research on (a) total project cost comparisons with concrete and steel, (b) hybrid systems and (c) mass timber building construction methods and guidelines. The most important barriers for successful adoption are (a) misconceptions about mass timber with respect to fire and building longevity, (b) high and uncertain insurance premiums, (c) higher cost of mass timber products compared to concrete and steel, and (d) resistance to changing from concrete and steel. In terms of challenges: (a) building code compliance and regulations, (b) design permits and approvals, and (c) insufficient design experts in the market are rated by study participants as the most pressing “engineering” challenge. The top procurement challenges are (a) too few manufactures and suppliers, (b) long distance transportation, and (c) supply and demand gaps. The most important construction challenges are (a) inadequate skilled workforce, (b) inadequate specialized subcontractors, and (c) excessive moisture exposure during construction.
Timber has been considered as a promising building material because of its structural rigidity, environmental sustainability, and renewability nature. In Europe and Australia, timber materials have been used for many different types of construction such as residential, commercial, education, and industrial. However, in the U.S., the familiarity of timber products is gaining momentum. The construction practitioners are still reluctant to consider mass timber as a mainstream building material. A limited number of case study projects make it difficult for industry personnel to evaluate the actual construction feasibility of mass timber. As a result, a significant knowledge gap has been created that hindering the progress of mass timber material in the U.S. construction industry. To help solve the problem, this study aims to identify the existing awareness level among the U.S. building constructors regarding mass timber building materials. It further determines some of the major construction-related difficulties of mass timber buildings and recommendations overcome those difficulties to increase the acceptance of this material. The study performed a semi-structured questionnaire survey to carry out statistical analysis regarding mass timber building material. Analysis of descriptive statistics suggested that the level of awareness and involvement by the U.S. construction practitioners in mass timber building is still significantly low as 55% of the participants indicated no experience on mass timber building construction projects. Qualitative data analysis suggested that lack of experience in timber construction, poor coordination among the project parties, design-related difficulties, and high cost of mass timber panels are the biggest construction-related barriers to adopt this product. To overcome the existing difficulties, the study proposed an increasing number of timber building projects and manufacturing plants, effective early collaboration among the project parties, developing skilled workers, and a nation-wide promotion by the owners and the architects. The outcomes of this study will be helpful for the industry practitioners and the owners to adopt mass timber as a mainstream building material. The study will further increase the acceptance of this material in the U.S. construction industry.
Mass timber construction in Australia and New Zealand uses three main materials—laminated veneer lumber, glue laminated timber and cross-laminated timber (CLT). This article focuses on the use of mass timber in nonresidential construction—the use in single-family homes and apartments is not considered. In Australia and New Zealand, mass timber building technology has moved from being technologically possible to being a feasible alternative to reinforced concrete and steel construction. It has not taken over a large market share in either market and, as such, has not been a disruptive technology. The major changes in this market in the past 5-10 yr in Australia and New Zealand have been the development of new industrial capacity in CLT and the acquisition of computer controlled machining equipment to facilitate prefabrication of wooden building components. The development of new codes and standards and design guides is underway. The drivers of future growth in market share are expected to include more clients putting a higher weight on the various environmental benefits of building in wood, reduction in the real and perceived professional risk for builders and architects specifying mass timber construction, and fuller participation in the supply chain for timber buildings (from design to construction) by timber building specialists. Government policies to encourage the use of timber may also be helpful. Engineers and architects will continue to learn—through experience—how to optimize building construction methods to take advantage of the specific features and qualities of timber as a construction method.