Impact of cracks to the hygrothermal properties of CLT water vapour resistance and air permeability

Kukk, Villu; Horta, Ricardo Augusto dos Santos; Püssa, M.; Luciani, Giulia; Kallakas, Heikko; Kalamees, Targo; Kers, Jaan

doi:10.1016/j.egypro.2017.10.019

Cited by 16 publications

(7 citation statements)

References 2 publications

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“…5 layer specimens combined with edge bonding had the most considerable effect on avoiding air leakages through the panel. The greater number of layers helps to avoid any overlapping of gaps between laminations which are possible sources of air leakages (Kukk, et al, 2017). The same argument was confirmed in this study as 3 layer specimens had considerably bigger air leakages, especially the specimens with laminations initially conditioned in an environment with RH of 70%.…”

Section: Discussionsupporting

confidence: 82%

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The effects of production technologies on the air permeability properties of cross laminated timber

Kukk¹,

Kalamees²,

Kers³

2018

Healthy, Intelligent and Resilient Buildings and Urban Environments

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In building envelope, the cross laminated timber (CLT) is often used as air barrier layer. The objective of this study was to evaluate the impact of production technologies such as edge bonding, different initial moisture content (MC) of lamination, and number of lamination layers (3 and 5) on the air-permeability properties of cross laminated timber. Air leakage and crack growth in CLT panels were measured after the panels were conditioned in environments with different relative humidity (RH) in progressive steps from humid to dry environments (RH 70%→ RH 50%→ RH 30%→ RH 10%). The test results showed that the most effective technologies for avoiding large crack growth and air leakages through panels were to use 5 layers of laminations with bonded edges. Overall, it can be recommended that for the production of CLT panels it is advisable to use primarily a larger number of layers, at least 5, for smaller growth of cracks on panel surfaces and thereby avoid air leakages during the time of use. The use of bonded edge technology helps to ensure the avoidance of possible air leakage threats, but in the long-term, this beneficial effect might decrease as bond layers may rupture or cracks may form in the middle of laminations.

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Section: Discussionsupporting

confidence: 82%

“…In building envelope, the CLT is often used as air barrier layer. Crack formation in CLT influences it's water vapour resistance and air permeability (Kukk et al 2017) as well fire resistance, acoustic properties, and lower the quality (Brander, 2013). Moisture movement in wood has a major role in crack formation.…”

Section: Introductionmentioning

confidence: 99%

The effects of production technologies on the air permeability properties of cross laminated timber

Kukk¹,

Kalamees²,

Kers³

2018

Healthy, Intelligent and Resilient Buildings and Urban Environments

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“…The greater number of layers helps to avoid any overlapping of gaps between laminations which are possible sources of air leakages (Kukk et al, 2017). The reason for better airtightness in panels with a larger number of layers is the same as it was for low crack growth, which was a larger number of bond layers and thinner laminations.…”

Section: Discussionmentioning

confidence: 99%

“…In the building envelope, a cross-laminated timber (CLT) is often used as an air barrier layer. Crack formation in CLT influences its water vapour resistance and air permeability (Kukk et al, 2017), as well as fire resistance and acoustic properties, and lowers the quality (Brandner, 2013).…”

Section: Introductionmentioning

confidence: 99%

The effects of production technologies on the air permeability and crack development of cross-laminated timber

Kukk

Kalamees

Kers

2019

Journal of Building Physics

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In a building envelope, the cross-laminated timber is often used as an air barrier layer. The objective of this study was to evaluate the impact of production technologies such as edge bonding, different initial moisture content of lamination and number of lamination layers (three and five) on the air permeability properties of the cross-laminated timber. Air leakage and crack area in cross-laminated timber panels were measured after the panels were conditioned in environments with different relative humidities in progressive steps from humid to dry environments (relative humidity 75% → relative humidity 43% → relative humidity 30% → relative humidity 15%). The test results showed that the five-layer specimens combined with initially drier laminations had the most considerable effect on avoiding air leakages through the panel. The greater number of layers helps to avoid any overlapping of gaps between laminations that are possible sources of air leakages. Based on the results, it is recommended to combine the technologies of using a larger number of layers together with initially drier laminations to minimise the growth of cracks on panel surfaces and avoid air leakages during the time of use.

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“…The wetting and drying behaviours of CLT panels and CLT wall assemblies have been investigated through laboratory test, field measurement and hygrothermal simulations [3][4][5][6]. Most of the previous studies, particularly hygrothermal modelling assumed homogeneous and isotropic material properties for entire CLT panel when assessing its moisture responses to environmental variations.…”

Section: Introductionmentioning

confidence: 99%

Wetting and drying performance of cross-laminated timber related to on-site moisture protections: Field measurements and hygrothermal simulations

Wang

2020

E3S Web Conf.

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Cross-laminated timber (CLT) panels are increasingly used in mid-rise buildings or even taller structures in North America. However, prolonged exposure to moisture during construction and in service is a durability concern for most wood products including CLT. To investigate practical solutions for reducing on-site wetting of mass timber construction, CLT specimens with a range of moisture protection measures, in six groups were tested in the backyard of FPInnovations’ Vancouver laboratory from Oct. 2017 to Jan. 2018. This study investigates the wetting and drying behaviours of the tested CLT specimens through 2-D hygrothermal simulations. The simulations are performed for base specimens (no protection measures) of group 1 (without joint or plywood spline) and group 2 (with a butt joint and plywood spline). For group 1, three data sources of material properties are used to create the models, and the data that led to the best agreement between simulations and measurement are used for creating the models of group 2. For group 2, two types of hygrothermal models are created with or without considering the differences in water absorption between the transverse and the longitudinal grain orientations. In addition, rain penetration is taken into account for the joint area. It is found that the model with considering the differences between transverse and longitudinal grain orientations shows a better agreement than that without considering such differences.

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Impact of cracks to the hygrothermal properties of CLT water vapour resistance and air permeability

Cited by 16 publications

References 2 publications

The effects of production technologies on the air permeability properties of cross laminated timber

The effects of production technologies on the air permeability properties of cross laminated timber

The effects of production technologies on the air permeability and crack development of cross-laminated timber

Wetting and drying performance of cross-laminated timber related to on-site moisture protections: Field measurements and hygrothermal simulations

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