Cross-laminated timbers (CLTs) are strong and lightweight structural building materials. CLTs are made from renewable wood resources and have significant economic potential as a new value-added product for the United States. However, market penetration has been obstructed by product affordability and lack of availability for use. Previous studies and projects have surveyed opinions of designers and contractors about the adoption of CLTs. No previous study was found that surveyed cost estimators, who serve the essential function of creating economic comparisons of alternative materials in commercial construction. CLTs are not included in these current cost estimation tools and software packages which may be limiting the potential use of CLT in construction.
The purpose of this study was to discover if cost estimation is being used to make structural decisions potentially affecting the marketability of CLT use in construction and building design because of the ability to estimate CLTs adequately. Through the use of a survey, the re-designing of a building, and discussions with subject matter experts, this study examined the knowledge level of cross-laminated timbers of under-surveyed building construction professions and the relationship between cost estimation and structural material choices. Their responses are demonstrating the need for better cost estimation tools for cross-laminated timbers such as inclusion in the Construction Specifications Institute's classification systems in order for CLTs to become a more competitive product. The study concluded that cost estimation is important for CLT market development, because it is being used extensively in the construction industry.
The research presents a Carbon Value Engineering framework. This is a quantitative value analysis method, which not only estimates cost but also considers the carbon impact of alternative design solutions. It is primarily concerned with reducing cost and carbon impacts of developed design projects; that is, projects where the design is already a completed to a stage where a Bill of Quantity (BoQ) is available, material quantities are known, and technical understanding of the building is developed.
This research demonstrates that adopting this integrated carbon and cost method was able to reduce embodied carbon emissions by 63-267 kgCO2-e/m2 (8-36%) when maintaining a concrete frame, and 72-427 kgCO2-e/m2 (10-57%) when switching to a more novel whole timber frame. With a GFA of 43,229 m2 these savings equate to an overall reduction of embodied carbon in the order of 2,723 – 18,459 tonnes of CO2-e. Costs savings for both alternatives were in the order of $127/m2 which equates to a 10% reduction in capital cost.
For comparison purposes the case study was also tested with a high-performance façade. This reduced lifecycle carbon emissions in the order of 255 kgCO2-e/m2, over 50 years, but at an additional capital cost, due to the extra materials. What this means is strategies to reduce embodied carbon even late in the design stage can provide carbon savings comparable, and even greater than, more traditional strategies to reduce operational emissions over a building’s effective life.
This paper aims to develop an artificial neural network (ANN) to predict the energy consumption and cost of cross laminated timber (CLT) office buildings in severe cold regions during the early stage of architectural design. Eleven variables were selected as input variables including...
The Task Group on Combustible Construction is in the process of evaluating a proposed code change request related to buildings of encapsulated mass timber construction (EMTC). As part of the analysis of the code change request, an impact analysis is required that includes a cost-benefit analysis.
Hanscomb was hired to provide a cost-benefit analysis and to compare the estimated value of the following:
1. The cost of constructing a building of mass timber (unprotected) versus a building constructed of encapsulated mass timber (e.g. mass timber protected with a double layer of Type X gypsum board) versus a traditional concrete and steel building.
2. The time to build a building of mass timber construction (unprotected) versus a building of encapsulated mass timber construction versus a traditional concrete and steel building.
3. The annual maintenance costs of building of mass timber construction versus a building of encapsulated mass timber construction versus a traditional concrete and steel building.
For the purposes of this study two sets of conceptual floor plans and elevations have been created:
1. A 12 storey building with a Group C major occupancy (residential) where each storey is 6,000 m2 in floor area.
2. A 12 storey building with a Group D major occupancy (office) where each storey is 7,200 m2 in floor area.
Recent changes to the National Building Code of Canada (NBC), and a trend towards more diversified housing options, have meant that many Canadian jurisdictions are acting quickly to capture the environmental, economic and social benefits of higher wood buildings. The 2015 NBC now permits wood frame construction to be 6 storeys high. Today, already 75% of Canadians live in jurisdictions that allow 6 storey wood frame construction. With the overall benefits of using wood as a building material well documented, Atlantic WoodWORKS!
studied the opportunities for 6 storey wood construction in Atlantic Canadian Centres. The research included a comprehensive market study and projections for mid-rise demand in
four major centres in Atlantic Canada, a review of recent and upcoming planning changes in major Atlantic Canadian cities and a full cost analysis, comparing wood construction to three
other construction methods in use in the Atlantic market using a real-life wood mid-rise structure built by an experienced builder.
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.
Composite structures use the advantages of two materials – timber and concrete – and improve the efficiency of a material application. Especially the concept of timber-concrete-composite ceilings has synergetic effects to achieve an effective ratio of thickness to span with high cost effectiveness simultaneously. Following the systematic...
The report describes a new structural system in wood that is the first significant challenger to concrete and steel structures since their inception in tall building design more than a century ago. The introduction of these ideas is fundamentally driven by the need to find safe, carbon-neutral and sustainable alternatives to the incumbent structural materials of the urban world. The market for these ideas is quite simply enormous. The proposed solutions have significant capacity to revolutionize the building industry to address the major challenges of climate change, urbanization, sustainable development and world housing needs.