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6 records – page 1 of 1.

Expanding the Cross-Laminated Timber Market through Building Moisture Monitoring and Improved Modeling

https://research.thinkwood.com/en/permalink/catalogue2269
Topic
Moisture
Material
CLT (Cross-Laminated Timber)
Organization
Colorado School of Mines
Forest Products Laboratory
Country of Publication
United States
Material
CLT (Cross-Laminated Timber)
Topic
Moisture
Keywords
Moisture Performance
Moisture Content
Mass Timber
Research Status
In Progress
Notes
Project contacts are Shiling Pei at the Colorado School of Mines and Samuel L. Zelinka at the Forest Products Laboratory
Summary
This project will generate three benchmark data sets for multistory CLT building moisture performance in different climate zones. Data will include moisture contents at key wood components and high moisture risk locations throughout the buildings. A relatively simple, but fully validated, numerical model for analyzing similar building moisture performance will be recommended. These results will be useful for structural engineers and architects to accurately consider moisture in their design of mass timber buildings.
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Hygrothermal Characterization and Modeling of Cross-Laminated Timber in the Building Envelope

https://research.thinkwood.com/en/permalink/catalogue2562
Year of Publication
2020
Topic
Moisture
Design and Systems
Material
CLT (Cross-Laminated Timber)
Application
Building Envelope
Author
Kordziel, Steven
Glass, Samuel
Boardman, Charles
Munson, Robert
Zelinka, Samuel
Pei, Shiling
Tabares-Velasco, Paulo
Year of Publication
2020
Country of Publication
United States
Format
Journal Article
Material
CLT (Cross-Laminated Timber)
Application
Building Envelope
Topic
Moisture
Design and Systems
Keywords
Building Envelope
Hygrothermal Modeling
Moisture Performance
Water Uptake
Hygric Redistribution
Language
English
Research Status
Complete
Series
Building and Environment
Summary
Cross-laminated timber (CLT) is a type of mass timber panel used in floor, wall, and roof assemblies. An important consideration in design and construction of timber buildings is moisture durability. This study characterized the hygrothermal performance of CLT panels with laboratory measurements at multiple scales, field measurements, and modeling. The CLT panels consisted of five layers, four with spruce-pine-fir lumber and one with Douglas-fir lumber. Laboratory characterization involved measurements on small specimens that included material from only one or two layers and large specimens that included all five layers of the CLT panel. Water absorption was measured with panel specimens partially immersed in water, and a new method was developed where panels were exposed to ponded water on the top surface. This configuration gave a higher rate of water uptake than the partial immersion test. The rate of drying was much slower when the wetted surface was covered with an impermeable membrane. Measured hygrothermal properties were implemented in a one-dimensional transient hygrothermal model. Simulation of water uptake indicated that vapor diffusion had a significant contribution in parallel with liquid transport. A simple approximation for liquid transport coefficients, with identical coefficients for suction and redistribution, was adequate for simulating panel-scale wetting and drying. Finally, hygrothermal simulation of a CLT roof assembly that had been monitored in a companion field study showed agreement in most cases within the sensor uncertainty. Although the hygrothermal properties are particular to the wood species and CLT panels investigated here, the modeling approach is broadly applicable.
Online Access
Free
Resource Link
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Operational Performance of Cross Laminated Timber: Brock Commons Tallwood House

https://research.thinkwood.com/en/permalink/catalogue2679
Year of Publication
2020
Topic
Moisture
Serviceability
Material
CLT (Cross-Laminated Timber)
Application
Columns
Walls
Organization
UBC Sustainability Initiative
Year of Publication
2020
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Columns
Walls
Topic
Moisture
Serviceability
Keywords
Moisture Content
Moisture Performance
Monitoring
Vertical Movement
Panels
Language
English
Research Status
Complete
Summary
The Tallwood House project was intended to advance the design and manufacture of mass timber products in Canada and demonstrate that mass timber is a viable structural option for mid-rise and high-rise buildings. The use of mass timber and engineered wood products in high-rise construction is becoming more common around the world leading to a growing interest in the performance of mass timber over time. This report describes the performance of the mass timber structure in Tallwood House, between September 2017 and August 2019, based on measurements of the moisture content in the prefabricated CLT floor panels and the displacement of the vertical structural system. It is intended to initiate discussions on the performance of mass timber structure elements during building occupancy and lead to further research that can explore the influential factors.
Online Access
Free
Resource Link
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Overcoming Market Barriers to Increase Use of Structural Mass Timber in Healthcare Environment

https://research.thinkwood.com/en/permalink/catalogue2567
Topic
Market and Adoption
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Hybrid Building Systems
Organization
University of Oregon
Country of Publication
United States
Material
CLT (Cross-Laminated Timber)
Application
Wood Building Systems
Hybrid Building Systems
Topic
Market and Adoption
Keywords
Healthcare
Hygienic Performance
Moisture Performance
Research Status
In Progress
Notes
Project contact is Kevin Van Den Wymelenberg at the University of Oregon
Summary
The goal of this project is to accelerate the application of structural mass timber, such as cross-laminated timber (CLT), in outpatient healthcare construction. In particular, this project will address concerns related to hygienic and moisture performance of CLT, as well as exploring other challenges faced in mass timber construction. The project will engage with industry partners representing architecture, engineering, and construction (AEC), healthcare professionals, and policy-makers to advance the state of knowledge and market penetration of CLT in healthcare. Healthcare construction is a large and growing sector; pioneering the use of CLT in this market would significantly increase utilization of small-diameter and lower-quality timber. Ultimately, successful implementation of this project would help achieve USFS regional priorities of supporting ecosystem restoration and wildland fire management, as well as Oregon’s State Forest Action Plan goals of protecting communities at risk of wildfire, maintaining the forestland base, and preserving diversity of upland habitats.
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Preliminary Assessment of Hygrothermal Performance of Cross-Laminated Timber Wall Assemblies Using Hygrothermal Models

https://research.thinkwood.com/en/permalink/catalogue2628
Year of Publication
2010
Topic
Moisture
Design and Systems
Serviceability
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Application
Walls
Author
Wang, J.
Baldracchi, P.
Organization
FPInnovations
Year of Publication
2010
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Light Frame (Lumber+Panels)
Application
Walls
Topic
Moisture
Design and Systems
Serviceability
Keywords
Hygrothermal
Moisture Performance
Rainscreen
Language
English
Research Status
Complete
Summary
Preliminary simulation was carried out using hygIRC and WUFI, both 1-D hygrothermal models, to analyze moisture performance of rainscreened wood-frame walls and cross-laminated timber (CLT) walls for the climates in Vancouver and Calgary. The major results are as follows. In order to provide baseline knowledge, preliminary comparisons between hygIRC and WUFI were conducted to investigate the effects of climate data, wall orientations and rain intrusion on the performance of the rainscreened wood-frame walls based on Vancouver’s climate. hygIRC tended to produce almost constant moisture content (MC) of the plywood sheathing throughout a year but WUFI showed greater variations, particularly when the ventilation of the rainscreen cavity was neglected. Rainscreen cavity ventilation provided dramatic drying potentials for wall assemblies based on the WUFI simulation. hygIRC indicated that east-facing walls had the highest moisture load, but the differences between orientations seemed negligible in WUFI when the rainscreen cavity ventilation was taken into account. When 1% of wind-driven rain was simulated as an additional moisture load, hygIRC suggested that the rainscreen walls could not dry out in Vancouver, WUFI, however, indicated that they could dry to a safe MC level in the summer. The discrepancies in material property data between the two models and between different databases in WUFI (even for the same wood species) were found to be very large. In terms of wood sorption data, large differences existed at near-saturated RH levels. This is a result of using pressure-plate/membrane methods for measuring material equilibrium moisture content (EMC) under high RH conditions. The EMC of wood at near-100% RH conditions measured with these methods can be higher than 200%, suggesting wood in construction would decay without liquid water intrusion or severe vapour condensation. The pressure-plate/membrane methods also appeared to be highly species-dependent, and have higher EMC at a certain RH level for less permeable species, from which it is relatively difficult to remove water during the measurement. The hygrothermal simulation in this work suggested that such a species bias caused by testing methods could put impermeable species (most Canadian species) at a disadvantage to permeable species like southern pine during related durability design of building assemblies. In terms of using CLT for construction in Vancouver and Calgary, the WUFI simulations suggested that the use of less permeable materials such as EPS (expanded polystyrene insulation), XPS (extruded polystyrene insulation), self-adhered bituminous membrane and polyethylene in wall assemblies reduced the ability of the walls to dry. On the other hand, permeable assemblies such as those using relatively permeable insulation like semi-rigid mineral wool (rock wool) as exterior insulation, instead of less permeable exterior insulation materials, would help walls dry. The simulation also suggested that using CLT products with initially low MC would significantly reduce moisture-related risks, which indicated the importance of protecting CLT and avoiding wetting during transportation and construction. In addition, the simulation found that indoor relative humidity (RH) conditions generated by the indoor RH prediction models included in hygIRC and WUFI varied greatly under the same basic climate and building conditions. The intermediate method specified in ASHRAE Standard 160 P resulted in long periods of saturated RH conditions throughout a year for the Vancouver climate, which may not be representative of ordinary residential buildings in Vancouver. The simulation in this study is preliminary and exploratory. It would be arbitrary to recommend one model over the other based on this report or use the simulation results directly for CLT wall assembly design without consultation with building science specialists. However, this work revealed more opportunities for close collaborations between the wood science and the building science communities. More work should be carried out to develop appropriate testing methods and assemble material property data for hygrothermal simulation of wood-based building assemblies. Model improvement and field verification are also strongly recommended, particularly for new building systems such as CLT constructions.
Online Access
Free
Resource Link
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Structural Performance Monitoring Technology and Data Visualization Tools and Techniques – Featured Case Study: UBC Tallwood House

https://research.thinkwood.com/en/permalink/catalogue2342
Year of Publication
2018
Topic
Moisture
Serviceability
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Columns
Floors
Author
Mustapha, Gamal
Khondoker, Khaleed
Higgins, James
Year of Publication
2018
Country of Publication
Canada
Format
Conference Paper
Material
CLT (Cross-Laminated Timber)
Glulam (Glue-Laminated Timber)
Application
Columns
Floors
Topic
Moisture
Serviceability
Keywords
Moisture Performance
Vertical Movement
Prefabrication
Language
English
Conference
International Conference on New Horizons in Green Civil Engineering
Research Status
Complete
Summary
Wood structures such as the Wood Innovation and Design Center in Prince George and the UBC Tallwood House, an 18 storey, 53-meter-tall mass timber hybrid building are examples of new and innovative wood structures that encompass new construction techniques, unique materials and novel building practices. Empirical data on the condition of critical components and access to the real-time status of the structure during construction gives Architects, Engineers and Contractors critical information to make informed decisions to either validate or improve the construction plan. Data recorded during the life of the building helps validate the design decisions and proves the viability and feasibility of the design. Methods and practices used to monitor both the moisture performance of prefabricated cross laminate timber (CLT) as well as the vertical movement sensing of the building during and after construction are explored in this paper. Moisture content of the CLT panels has been recorded from manufacturing and prefabrication to storage, through transport and during installation and will continue throughout the service life of the building. The calculated and expected displacement of the wood columns is scheduled to take several years as the structure settles, however a first-year analysis and extrapolation of the data was conducted. Monitoring during transport, storage, and construction proved that CLT panels were resilient to moisture issues while in the manufacturers storage, but prone to direct exposure to moisture-related problems regardless of the precautions taken on site. Despite construction during typical Pacific Northwest rain, informed decisions were made to ensure the panel moisture content could decrease to acceptable ranges before continuing to secondary construction phases. The moisture trends observed in the building were proportional to the control samples as both were subjected to similar environmental conditions.
Online Access
Free
Resource Link
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6 records – page 1 of 1.