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6 records – page 1 of 1.

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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Solutions for Upper Mid-Rise and High-Rise Mass Timber Construction: Rehabilitation of Mass Timber Following Fire and Sprinkler Activation

https://research.thinkwood.com/en/permalink/catalogue2089
Year of Publication
2019
Topic
Fire
Moisture
Material
Timber (unspecified)
Application
Wood Building Systems
Author
Ranger, Lindsay
Organization
FPInnovations
Year of Publication
2019
Country of Publication
Canada
Format
Report
Material
Timber (unspecified)
Application
Wood Building Systems
Topic
Fire
Moisture
Keywords
Mid-Rise
High-Rise
Damage
Repairs
Sprinklers
Language
English
Research Status
Complete
Summary
The intent of this project is to research evaluation and rehabilitation methods that are applicable to mass timber structures following a fire. This includes addressing both fire damage and water damage from sprinkler activation and/or the use of firefighting hoses. This report provides an overview of the type of damage that might be expected following a fire and methods that might reduce potential damage (including design elements and firefighting tactics). Current and existing rehabilitation methods for wood construction will be reviewed and their applicability to mass timber structures will be discussed. This includes the ability to conduct condition assessments and repairs on building elements that can be done in place. The overall objective is to reduce uncertainty related to mass timber construction, which ultimately would allow for more accurate risk evaluation by insurance companies.
Online Access
Free
Resource Link
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Taller and Larger Wood Buildings: Potential Impacts of Wetting on Performance of Mass Timber Buildings

https://research.thinkwood.com/en/permalink/catalogue372
Year of Publication
2016
Topic
Serviceability
Moisture
Application
Wood Building Systems
Author
Wang, Jieying
Organization
FPInnovations
Year of Publication
2016
Country of Publication
Canada
Format
Report
Application
Wood Building Systems
Topic
Serviceability
Moisture
Keywords
Wetting
Drying
Wood-Moisture Relationship
Language
English
Research Status
Complete
Summary
This report summarizes basic wood-moisture relationships, and reviews conditions conducive to adverse consequences of wetting, such as staining, mold growth, decay, strength reduction, and dimensional change and distortion. It also outlines solutions and available resources related to on-site moisture management and design measures.
Online Access
Free
Resource Link
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US Edition - Chapter 10: Building Enclosure Design for Cross-Laminated Timber Construction

https://research.thinkwood.com/en/permalink/catalogue829
Year of Publication
2013
Topic
Design and Systems
Moisture
Material
CLT (Cross-Laminated Timber)
Application
Roofs
Walls
Author
Glass, Samuel
Wang, Jieying
Easley, Steve
Finch, Graham
Organization
FPInnovations
Binational Softwood Lumber Council
Year of Publication
2013
Country of Publication
Canada
United States
Format
Book Section
Material
CLT (Cross-Laminated Timber)
Application
Roofs
Walls
Topic
Design and Systems
Moisture
Keywords
Airflow
Climate
Heat
Moisture Control
Building Enclosure
Exterior Walls
Language
English
Research Status
Complete
Series
CLT Handbook - US Edition
Summary
Cross-laminated timber (CLT) was developed in Europe for the prefabricated construction of wall, roof, and flooring elements. Adaption of CLT for use in the United States requires consideration of the different climates, building codes, and construction methods in this country. ... This Chapter provides guidance on hear, air, and moisture control in wall and roof assemblies that utilize CLT panels in U.S. climate zones. The overarching strategies are to prevent wetting of CLT panels by using drained wall systems, to control airflow using an air barrier on the exterior of the CLT panels, to place rigid insulation to the exterior of the panels, to prevent moisture from accumulating within the panels, and to allow the panels to dry should they get wet. In certain climates, preservative treatment of CLT is recommended to provide additional protection against potential hazards such as decay and termites. ...
Online Access
Free
Resource Link
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Wetting and Drying Performance and On-site Moisture Protection of Nail-Laminated Timber Assemblies

https://research.thinkwood.com/en/permalink/catalogue1871
Year of Publication
2016
Topic
Moisture
Material
NLT (Nail-Laminated Timber)
CLT (Cross-Laminated Timber)
Application
Walls
Wood Building Systems

Wetting and Drying Performance Related To On-Site Moisture Protection of Cross-Laminated Timber

https://research.thinkwood.com/en/permalink/catalogue1169
Year of Publication
2018
Topic
Moisture
Site Construction Management
Material
CLT (Cross-Laminated Timber)
Application
Hybrid Building Systems
Wood Building Systems
Author
Wang, Jieying
Organization
FPInnovations
Year of Publication
2018
Country of Publication
Canada
Format
Report
Material
CLT (Cross-Laminated Timber)
Application
Hybrid Building Systems
Wood Building Systems
Topic
Moisture
Site Construction Management
Keywords
On-Site
Moisture Management
Water Repellants
Rain
Language
English
Research Status
Complete
Summary
Project objectives: To investigate the wetting and drying behaviour of the face and edge surfaces of cross-laminated timber (CLT), including edge-to-edge joints covered with plywood spline To evaluate effectiveness of water-repellent coatings and membranes that are factory-applied with the intent to prevent wetting caused by rain, installation of wet light-weight concrete topping, or contact with damp concrete surfaces To assess potential impact of fire protection measures including drywall and rigid mineral wood insulatio on the drying performance of wet CLT To further develop practical solutions for on-site management of mass timber construction
Online Access
Free
Resource Link
Less detail

6 records – page 1 of 1.