The two primary considerations for construction project management are budget and time management. Modular construction has the potential to improve construction productivity by minimizing time and costs while improving safety and quality. Cross-Laminated Timber (CLT) panels are beneficial for modular construction due to the high level of prefabrication, adequate dimensional stability, and good mechanical performance that they provide. Accordingly, CLT modular construction can be a feasible way to speed up the construction and provide affordable housing. However, an in-depth study is needed to streamline the logistics of CLT modular construction supply chain management. CLT modular construction can be performed by two primary means based on type of modules produced: panelized (2D) and volumetric (3D). This research aims to help the Architecture, Engineering, and Construction (AEC) industry by developing a tool to assess the impact of various logistical factors on both panelized and volumetric modular construction productivity. Discrete-Event Simulation (DES) models were developed for panelized and volumetric CLT modular construction based on a hypothetical case study and using data collected from superintendents and project managers. Sensitivity analysis is conducted using the developed models to explore the impact of selected manufacturing and logistical parameters on overall construction efficiency. Comparing volumetric and panelized simulations with the same number of off-site crews revealed that the volumetric model has lower on-site process duration while the off-site process is significantly longer. Accordingly, from manufacturing to the final module assembly, the total time for the volumetric model is longer than panelized model. Moreover, the simulations showed that volumetric modular construction is associated with less personnel cost since the main process is performed off-site, which has lower labor costs and a smaller number of crews required on-site. This framework could be used to identify the optimum construction process for reducing the time and cost of the project and aid in decision-making regarding the scale of modularity to be employed for project.
Project contact is Y.H. Chui at the University of Alberta
The objective of this research is to develop efficient panel-to-panel connection details, and optimum floor configuration, including rigging details, for handling in the factory and at the construction site. Computer modelling will be conducted to develop preliminary recommendations on panel-to-panel connection details and optimum floor panel configuration. These recommendations will then be validated by a testing program in the laboratory.
Project contact is Jean-François Lalonde at Université Laval
Mobile digital tools (tablets and mobile phones) are ubiquitous in our lives. The potential of the cameras of these tools is under-exploited if we consider the geo-spatial information that they can provide to the information management systems (BIM) via cloud platforms for example. The images captured by these cameras can be combined with information from other sensors (gyroscope, accelerometers, etc.) and thus aligned with a BIM model. Many of these technologies are commonly used for robotic localization. The project would aim to assess whether current technologies could be used to track construction progress and identify non-conformities. The project would also determine the level of precision that can be achieved.
This report provides an overview of major changes occurred in the recent decade to design and construction of the building envelope of wood and wood-hybrid construction. It also covers some new or unique considerations required to improve building envelope performance, due to evolutions of structural systems, architectural design, energy efficiency requirements, or use of new materials. It primarily aims to help practicioners better understand wood-based building envelope systems to improve design and construction practices. The information provided should also be useful to the wood industry to better understand the demands for wood products in the market place. Gaps in research are identified and summarized at the end of this report.
Many strategies have been investigated seeking for efficiency in construction sector, since it has been pointed out as the largest consumer of raw materials worldwide and responsible of about 1/3 of the global CO2 emissions. While operational carbon has been strongly reduced due to building regulations, embodied carbon is becoming dominating. Resources and processes involved from material extraction to building erection should be carefully optimized aiming to reduce the emissions from the cradle to service. New advancements in timber engineering have shown the capabilities of this renewable and CO2 neutral material in multi-storey buildings. Since their erection is based on prefabrication, an accurate construction management is eased where variations and waste are sensible to be minimized. Through this paper, the factors constraining the use of wood as main material for multi-storey buildings will be explored and the potential benefits of using Lean Construction principles in the timber industry are highlighted aiming to achieve a standardized workflow from design to execution. Hence, a holistic approach towards industrialization is proposed from an integrated BIM model, through an optimized supply chain of off-site production, and to a precise aligned scheduled on-site assembly.
This work was carried in support of NRC’s Mid-rise Wood Buildings (MRWB) program, whose objective is to improve the performance of mid-rise and tall wood buildings. The main objective of the work was to determine the scope for future research to develop new technologies to prevent, fight and mitigate the impacts of fire during construction. The work involved an extensive literature review and some discussions with potential stakeholders to understand their views, concerns and research needs. The literature review covered approximately 115 publications (including magazine and newspaper articles). The current literature clearly identifies the significant fire risks faced by wood buildings during the construction phase and there are numerous examples of fires that have occurred at wood building construction sites. The literature review revealed that the current state-of-the-art essentially encompasses the development and promotion of safe working practices and fire safety guidelines for mid-rise wood buildings under construction, which is being adequately addressed by many industry stakeholders. There is a lack of research and methods to address the critical areas of active and passive fire protection during construction. This is likely due to the fact that the acceptance of mid-rise and tall wood buildings has only happened recently and was largely based on the fact that the fire safety of finished buildings is assured by proven adequacy of their fire resistance design features, such as the encapsulation approach, and mandatory requirements for fire protection systems, such as sprinklers. Therefore, NRC can make a more valuable contribution in areas where its existing fire research expertise and unique test facilities can lead to the development of new knowledge to improve safety in mid-rise wood buildings under construction by undertaking research in the following areas identified by this study: 1. Characterization of construction site fires and evaluation of detection systems; 2. Evaluation and development of active fire protection systems/technologies applicable to construction sites; 3. Evaluation and development of passive fire protection systems/technologies applicable to construction sites; 4. Improvement of firefighting tactics using scientific knowledge of construction site fires and effective suppression technologies. The research can be undertaken in phases, with Phase 1 focusing on the characterization of mid-rise wood construction site fires, evaluation and development of fire detection and suppression systems. Subsequent phases of the project could address the evaluation and development of cost-effective passive protection systems and the improvement of firefighting tactics using the fire scenarios developed in Phase 1. Further details of the potential scope for research in the above areas are presented and discussed in this report.
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.