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Construction moisture management, nail-laminated timber

https://library.fpinnovations.ca/fr/permalink/fpipub8035
Auteur
Wang, Jieying
Date
March 2021
Genre du document
Research report
Domaine
Sustainable Construction
. While “S-Dry” dimension lumber has moisture content (MC) of around 19% or lower when it is produced
Auteur
Wang, Jieying
Date
March 2021
Genre du document
Research report
Description physique
6 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Advanced Wood Materials
Sujet
Laminate product
Performance
Wood frame
Moisture content
Série
InfoNote 2021 N 15
Langue
English
Résumé
Nail-laminated timber (NLT) is a large built-up member often used as interior structural members for floors, roofs, walls, and elevator/stair shafts. Because prolonged wetting of wood may cause staining, mould, excessive dimensional change (sometimes enough to fail fasteners), and even result in decay and loss of strength, construction moisture is an important consideration when building with NLT. This document aims to provide technical information to help architects, engineers, and builders assess the potential for wetting of NLT during building construction and identify appropriate actions to mitigate the risks.
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Instrumentation for monitoring performance in a six-storey building in Vancouver built for high energy performance

https://library.fpinnovations.ca/fr/permalink/fpipub7512
Auteur
Wang, Jieying
Thomas, Tony
Date
March 2018
Édition
49833
Genre du document
Research report
Domaine
Sustainable Construction
Auteur
Wang, Jieying
Thomas, Tony
Collaborateur
Natural Resources Canada. Canadian Forest Service
Date
March 2018
Édition
49833
Genre du document
Research report
Description physique
24 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Advanced Wood Materials
Sujet
Monitoring
Performance
Buildings
Energy
Moisture content
Air
Série
Transformative Technology ; TT 2018
Langue
English
Résumé
This report documents the instrumentation installed for monitoring moisture, indoor air quality and differential movement performance in a six-storey building located in the City of Vancouver. The building has five storeys of wood-frame construction above a concrete podium, providing 85 rental units for residential and commercial use. It was designed and built to meet the Passive House standard and, once certified, will be the largest building in Canada that meets this rigorous energy standard. Although the design and construction focused on integrating a number of innovative measures to improve energy efficiency, much effort was also made to reduce construction costs. One example of the design measures is the use of a highly insulating exterior wall assembly that integrates rigid insulation between two rows of wall studs as interior air and vapour barriers. This monitoring study aims to generate data on long-term performance as part of FPInnovations’ effort to assist the building sector in developing durable and energy efficient wood-based buildings, which is expected to translate into reduced energy consumption and carbon emissions from the built environment. The monitoring focuses on measuring moisture performance of the building envelope (i.e., exterior walls, roof, and sill plates); indoor environmental quality including temperature, humidity, and CO2; and vertical differential movement between exterior walls and interior walls below roof/roof decks. In total, 79 instruments were installed during the construction. The next steps of this study will focus on collecting and analysing data from the sensors installed, and assessing performance related to the building envelope and vertical differential movement. FPInnovations will also collaborate with CanmetENERGY of Natural Resources Canada to monitor heat recovery ventilators and to assess whole-building energy efficiency and occupant comfort. This is expected to start after the mechanical systems are fully commissioned during occupancy. Results of these upcoming phases of work will be published in future reports.
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Taller and larger wood buildings : potential impacts of wetting on performance of mass timber buildings

https://library.fpinnovations.ca/fr/permalink/fpipub40151
Auteur
Wang, Jieying
Date
March 2016
Genre du document
Research report
Domaine
Sustainable Construction
Auteur
Wang, Jieying
Collaborateur
Natural Resources Canada. Canadian Forest Service
Date
March 2016
Genre du document
Research report
Description physique
43 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Advanced Wood Materials
Sujet
Building construction
Laminate product
Moisture content
Performance
Wood frame
Série
W3279
Localisation
Vancouver, British Columbia
Langue
English
Résumé
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. Sorption, including desorption (i.e., loss of moisture) and adsorption (i.e., gain of moisture), is the interaction of wood with the water vapour in the ambient environment. The consequent changes in the amount of bound moisture (or “hygroscopic moisture”) of pre-dried wood affect the physical and mechanical properties. However, the core of a mass timber responds slowly and is well protected from fluctuations in the service environment. Mold growth and fungal staining may occur in a damp environment with a high relative humidity or sources of water. Sorption alone does not increase the moisture content (MC) of pre-dried wood above the fibre saturation point and does not lead to decay. Wood changes its MC more quickly when it absorbs water compared with sorption. This introduces free water (or “capillary water”) and increases the MC above the fiber saturation point. Research has shown that decay does not start below a MC of 26%, when all other conditions are favourable for fungal growth. Decay can cause significant strength reduction, for toughness and impact bending in particular. For a wood member in service, the effect of decay is very complicated and depends on factors, such as the size of a member, loading condition, fungi involved, location and intensity of the attack. Appearance of decay does not reflect true residual stiffness or strength. For wood-based composites severe wetting without decay may affect the structural properties and performance due to damage to the bonding provided by the adhesive inside. There are large variations among wood species, products and assemblies in their tendency to trap moisture and maintain durability. For a given wood species, the longitudinal direction (vs. the transverse directions) and the sapwood (vs. heartwood) absorb water more quickly. Capillaries between unglued joints (e.g., some CLT, glulam), exposed end grains, and interconnected voids inside a product increase the likelihoods of moisture entrapment, slow drying, and consequently decay. Many mass timber products, composites in particular, may be modified to reduce these issues. Measures should also be taken in design, during construction, or building operation to reduce the moisture risk and increase the drying ability. It is also important to facilitate detection of water leaks in a mass timber building and to make it easier to repair and replace members in case damage occurs. Preservative-treated or naturally durable wood should be used for applications that are subjected to high moisture risk. Localized on-site treatment may be appropriate for specific vulnerable locations. Changing environmental conditions may cause issues, such as checking, although it does not compromise the structural integrity in most cases. Measures may be taken to allow the timbers to adjust to the service conditions slowly (e.g., through humidity control), particularly in the first year of service. Overall there is very little information about the potential impacts that various wetting scenarios during construction and in service could realistically have on mass timber products and systems. The wetting and drying behaviour, impacts of wetting and biological attack on the structural capacity, and the behaviour under extreme environmental conditions, such as the very dry service environment that occurs during the winter in a northern continent, should be assessed to improve design of mass timber buildings.
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Field measurement of vertical movement and roof moisture performance of the Wood Innovation and Design Centre : instrumentation and first year's performance

https://library.fpinnovations.ca/fr/permalink/fpipub44205
Auteur
Wang, Jieying
Date
March 2015
Genre du document
Research report
Domaine
Sustainable Construction
PDF
Ajoutez cet article à votre liste de sélections pour demander le PDF - Add this item to your selection list to request the PDF
Auteur
Wang, Jieying
Collaborateur
Forestry Innovation Investment
Date
March 2015
Genre du document
Research report
Description physique
39 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Advanced Wood Materials
Sujet
British Columbia
Building construction
Laminate product
Moisture content
Performance
Test methods
Série
301008940
Langue
English
Résumé
Two of the major topics of interest to those designing taller and larger wood buildings are the susceptibility to differential movement and the likelihood of mass timber components drying slowly after they are wetted during construction. The Wood Innovation and Design Centre in Prince George, British Columbia provides a unique opportunity for non-destructive testing and monitoring to measure the ‘As Built’ performance of a relatively tall mass timber building. Field measurements also provide performance data to support regulatory and market acceptance of wood-based systems in tall and large buildings. This report first describes instrumentation to measure the vertical movement of selected glulam columns and cross-laminated timber (CLT) walls in this building. Three locations of glulam columns and one CLT wall of the core structure were selected for measuring vertical movement along with the environmental conditions (temperature and humidity) in the immediate vicinity. The report then describes instrumentation to measure the moisture changes in the wood roof structure. Six locations in the roof were selected and instrumented for measuring moisture changes in the wood as well as the local environmental conditions. All sensors and instrumentations, with the exception of one, were installed and became operational in the middle of March 2014, after the roof sheathing was installed. The other instrumentation was installed in July 2014. This report presents performance of the building during its first year as measured from topping out of the structure. In the end, the one-year period covers six months of construction and six months of occupancy. This is the first year of a planned five-year monitoring. The first year’s monitoring showed that the wood inside the building had reached moisture content (MC) of about 4-6% in the heating season, from an initial MC of 13% during construction. Glulam columns were extremely dimensionally stable given the changes in MC and loading conditions. With a height of over 5 m and 6 m, respectively, the two glulam columns measured in this study showed very small amounts of vertical movement, each below 2 mm. The cumulative shortening of the six glulam columns along the height of the building would be about 8 mm, not taking into account deformation at connection details or effects of reduced loads on upper floors. The CLT wall was found to be also dimensionally stable along the height of the building. The measurements showed that the entire CLT wall, from Floor 1 to Floor 6, would shorten about 14 mm. The CLT floors, however, had considerable shrinkage in the thickness direction, and therefore should be taken into consideration in the design and construction of components, such as curtain walls, which are connected to the floors. In terms of the roof performance, two locations, both with a wet concrete layer poured above the plywood sheathing, showed wetness during construction but dried slowly afterwards. The good drying performance must be attributed to the interior ventilation function designed for the roof assemblies by integrating strapping between the sheathing and the mass timber beams below. Overall this monitoring study shows the differential movement occurring among the glulam columns and the CLT wall is small and the wood roof has good drying performance.
PDF
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Quantifying the impacts of moisture and load on vertical movement in a simulated bottom floor of a 6-storey platform frame building

https://library.fpinnovations.ca/fr/permalink/fpipub39705
Auteur
Wang, Jieying
King, L.
Date
March 2013
Genre du document
Research report
Domaine
Sustainable Construction
and constructed, with built-in vertical movement and moisture content monitoring systems. The two structures were
Auteur
Wang, Jieying
King, L.
Collaborateur
Natural Resources Canada. Canadian Forest Service.
Date
March 2013
Genre du document
Research report
Description physique
30 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Advanced Wood Materials
Sujet
Buildings
Building construction
Moisture content
Test methods
Série
Transformative Technologies Project No.301006157
W-3006
Localisation
Vancouver, British Columbia
Langue
English
Résumé
Vertical movement of wood frame buildings has become an important consideration in recent years with the increase of building height in Europe, North America, and Asia up to 6-storeys. This movement is composed of wood shrinkage and load-induced movement including initial settlement and creep. It is extremely difficult to identify the relative contributions of these components while monitoring full size buildings. A laboratory test was therefore designed to do this under controlled environmental and loading conditions. Two identical small-scale platform frame structures with dimensional lumber floor joists were designed and constructed, with built-in vertical movement and moisture content monitoring systems. The two structures were first conditioned in a chamber to achieve an initial moisture content (MC) about 20% to simulate typical MC on exposed construction sites in wintertime in Coastal BC. After the two structures were moved from the conditioning chamber into the laboratory environment, using a unique cantilever system, Structure No. 1 was immediately loaded to measure the combined shrinkage and deformation in the process of drying. Structure No. 2 was not loaded until after the wood had dried to interior equilibrium moisture content to observe the shrinkage and load-induced movement separately. The load applied on the two structures simulated a dead load experienced by the bottom floor of a six-storey wood frame building. The vertical movement and MC changes were monitored over a total period of six months. Meanwhile, shrinkage coefficients were measured by using end-matched lumber samples cut from the plate members of the two structures to predict the shrinkage amounts of the horizontal members of the two structures. The results suggested that a load must be applied for movement to “show up” and occur in a downward direction. Without loads other than the wood weight, even shrinkage could show as upward movement. Monitoring of Structure No. 1 appeared to separate the contributions of wood shrinkage, initial settlement (bedding-in movement), and creep reasonably well. The entire movement amount reached about 19 mm after six months, which was comparable to the vertical movement measured from the bottom floor of a 4-storey wood-frame building in BC. Shrinkage accounted for over 60% of the vertical movement, with the other 40% contributed by load-induced movement including initial settlement and creep (when elastic compression was neglected); the magnitude of creep was similar to the initial settlement amount. Structure No. 2 showed less vertical movement but an increased settlement amount at the time of loading, indicating the presence of larger gaps between members when the wood was dry (with an estimated MC of 11%) before loading. Depending on construction sequencing, such settlement should occur with increase in loads during construction and can therefore be ignored in design. However, this test suggested that there may be a need to consider the impact of creep, in wet climates in particular, in addition to wood shrinkage. This laboratory test will be maintained for a longer period to observe any further vertical movement and the relative contributions of shrinkage and creep. Similar tests should be conducted for structures built with engineered wood floor joists, given the fact that most mid-rise platform buildings use engineered wood floor joists instead of lumber joists.
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Des produits de qualité supérieure grâce au contrôle de l'humidité

https://library.fpinnovations.ca/fr/permalink/fpipub38912
Collaborateur
Forintek Canada Corp.
Date
December 2004
Genre du document
Pamphlet
Domaine
Sustainable Construction
Collaborateur
Forintek Canada Corp.
Date
December 2004
Genre du document
Pamphlet
Description physique
4 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Advanced Wood Materials
Sujet
Moisture content
Série
E-4009
Langue
French
Résumé
L’humidité relative de l’environnement influe non seulement sur la santé des êtres humains et des plantes, mais aussi sur la performance de matériaux organiques comme le papier, le bois et les textiles. Face à la pression constante en vue d’accroître la productivité et aux attentes sur le plan de la qualité uniforme des produits, l’industrie de la transformation secondaire des produits du bois doit prendre les mesures nécessaires pour assurer un certain taux d'humidité dans ses installations de transformation et d’entreposage du bois. Étant donné que les systèmes de chauffage, de ventilation et d’échappement entraînent une variation constante du climat intérieur, les systèmes d’humidification peuvent favoriser l’uniformité de la qualité à toutes les étapes des procédés de fabrication.
Moisture content
Quality control
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Improve product quality through humidity control

https://library.fpinnovations.ca/fr/permalink/fpipub38921
Collaborateur
Forintek Canada Corp.
Date
December 2004
Genre du document
Pamphlet
Domaine
Sustainable Construction
that it continually tries to achieve an equilibrium moisture content (EMC) within its environment. As such, when
Collaborateur
Forintek Canada Corp.
Date
December 2004
Genre du document
Pamphlet
Description physique
4 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Advanced Wood Materials
Sujet
Moisture content
Série
Technology Profile ; TP-04-02W
E-4018
Langue
English
Résumé
Just as human beings and plants need moisture to stay healthy, the same principle applies to organic materials such as paper, wood and textiles. With an ever-growing demand for increased productivity and the expectation of uniform product quality within the secondary wood manufacturing sector, natural materials such as wood require a climate in which processes and storage occur at a certain air humidity. As indoor climate and humidity constantly change with heating, ventilation and exhaust systems, humidification systems can help ensure uniform quality throughout production.
Moisture content
Quality control
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Performance evaluation of wood panels as exterior sheathing

https://library.fpinnovations.ca/fr/permalink/fpipub42200
Auteur
Thivierge, Constance
Date
June 2003
Genre du document
Research report
Domaine
Sustainable Construction
Auteur
Thivierge, Constance
Date
June 2003
Genre du document
Research report
Description physique
3 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Advanced Wood Materials
Sujet
Moisture content
Série
General Revenue 3635
Localisation
Sainte-Foy, Québec
Langue
English
Résumé
Buildings - Moisture content
Sheathing, exterior
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L'eau et la durabilité : fiche technique sur la performance de la construction à ossature de bois

https://library.fpinnovations.ca/fr/permalink/fpipub42416
Collaborateur
Forintek Canada Corp.
Canada Mortgage and Housing Corporation (CMHC)
Société centrale d'hypothèques et de logement (SCHL)
Date
April 2000
Genre du document
Pamphlet
Domaine
Sustainable Construction
Collaborateur
Forintek Canada Corp.
Canada Mortgage and Housing Corporation (CMHC)
Société centrale d'hypothèques et de logement (SCHL)
Date
April 2000
Genre du document
Pamphlet
Description physique
4 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Advanced Wood Materials
Sujet
Moisture content
Wood decay
Série
Fact Sheet on Wood in Construction = Fiche technique sur le bois dans la construction
Localisation
Québec, Québec
Langue
French
Résumé
Moisture - Control
Moisture - Prevention
Buildings - Houses - Moisture content
Decay - Prevention
Building construction - Design
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Decision aids for durable wood construction : review and redirection

https://library.fpinnovations.ca/fr/permalink/fpipub41201
Auteur
O'Connor, J.
Morris, Paul I.
Date
March 1999
Genre du document
Research report
Domaine
Sustainable Construction
of the assembly such as building paper and flashing, to enforce the building code requirement that the moisture
Auteur
O'Connor, J.
Morris, Paul I.
Collaborateur
Canada. Canadian Forest Service.
Date
March 1999
Genre du document
Research report
Description physique
28 p.
Secteur
Wood Products
Domaine
Sustainable Construction
Champ de recherche
Advanced Wood Materials
Sujet
Building construction
Planning
Design
Moisture content
Série
Canadian Forest Service No. 19
Project No. 1052
W-1611
Localisation
Vancouver, British Columbia
Langue
English
Résumé
The project Decision Aids for Durable Wood Construction underwent a major review with the hiring of a new project leader (O'Connor) in September 1998. In consultation with the project liaisons, the work on this project since its start-up in 1993 was examined, the primary task of developing a computer-based tool for the building industry was reconsidered, the context of worldwide research into building envelope moisture failures was reviewed, and a revised project plan was proposed. Decision Aids was a self-contained project for its first three years, with efforts concentrated on knowledge acquisition, expert system experimentation and other foundation work for development of a computer tool. With a rise of interest in building envelope moisture failures across North America and elsewhere, Decision Aids activity shifted into a mode that was reactive to projects and events external to Forintek. This was necessary due to the level of effort external agencies, media and research labs were devoting to the topic. In particular, where the actions of outsiders began to have an influence on wood in construction, we found it critical to participate in order to ensure the fair and correct treatment of wood. The new project leader was asked to review the project and either get the project back on its original track or suggest a redirection. The project goal, to assist end users in best application of wood, was determined to be sound. In addition, the project leader recommended that resources continue to be allocated to participation in outside research efforts and other related activities. However, it was recommended that the project objective to develop computer-based decision tools be reassessed. Instead, the project leader recommended a course of action focused on tasks both shorter in term and smaller in scope, which will enable Forintek to deliver results better tailored to the immediate needs of industry in a time of building envelope moisture failure "crisis." The new project plan is split into two areas: 1) address building envelope moisture failures that are due to existing information not arriving in the right hands (i.e., a technology transfer problem); and 2) address building envelope moisture failures that are due to a lack of information (i.e., a research problem). The technology transfer area will create a formal plan for communication to the building industry, will enable Forintek to experiment with developing pathways to that new target audience, and will provide the means for the wood industry to provide helpful durability information to the public through a relatively neutral third party (Forintek). The research area will explore opportunities for limited scope experiments or collaborative field studies of wood system durability performance, with the intent of verifying or modifying codes, standards and best practice guides.
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11 notices – page 1 of 2.