Advanced modelling of vapor resistance of moisture dependent vapor retarder

Fechner, Heiko; Meißner, Frank

doi:10.1016/j.egypro.2017.09.755

Cited by 3 publications

(2 citation statements)

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“…However, when using vapour retarders or SVBs, drying towards the interior becomes important to the drying performance of the structure [22]. The drying performance of SVBs and smart vapour retarders has been a subject of study in recent years by, e.g., Tariku et al [23], Yoshinaga [24], and Fechner and Meißner [25].…”

Section: Introductionmentioning

confidence: 99%

Water Vapour Resistance of Ceiling Paints—Implications for the Use of Smart Vapour Barriers in Compact Wooden Roofs

Tomren,

Andenæs,

Geving

et al. 2023

Buildings

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Smart vapour barriers enable building envelopes to dry toward the interior side. This property can be used in compact wooden roofs to create more slender structures by placing the wooden load-bearing elements inside the insulation layer. There is, however, some concern that the ceiling assembly on the interior side may inhibit inward drying by trapping moisture between the vapour barrier and the ceiling boards. This article examined the water vapour resistance of gypsum boards painted with two, four, and six layers of typical ceiling paints. WUFI® 2D simulations were conducted to assess the risk of mould growth in compact wooden roofs with painted board ceilings. It was found that a painted ceiling board may exhibit an equivalent stagnant air layer thickness (sd value) between 0.074 m for two layers of the most vapour-open paint and 0.53 m for six layers of the least vapour-open. For an unpainted board, the sd value was measured to be 0.071 m. The difference was not found to make a substantial impact on the drying of a typical compact wooden roof. The application of paint may cause the assembly to dry at a slightly slower rate but was not found to present a notably higher risk of mould growth, even under unfavourable conditions.

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Section: Introductionmentioning

confidence: 99%

Water Vapour Resistance of Ceiling Paints—Implications for the Use of Smart Vapour Barriers in Compact Wooden Roofs

Tomren,

Andenæs,

Geving

et al. 2023

Buildings

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“…The latest solution is the so-called Smart Vapor Barrier (SVB). The physical performance of these products varies, but the main principle is that the vapour barrier should function as an ordinary tight vapour barrier most of the time, preventing vapour diffusion into the construction from the indoor air (e.g., Sd-value at approximately 4-5 m when the RH is below about 40% [39][40][41]). If the construction becomes wet, the relative humidity (RH) on the exterior side of the vapour retarder becomes high, and the vapour resistance is reduced (e.g., Sd = 0.1-0.2 when the RH is above 80% [39][40][41]).…”

mentioning

confidence: 99%

Moisture Risk Analysis for Three Construction Variants of a Wooden Inverted Flat Roof

Sadłowska-Sałęga

Wąs

2021

Energies

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The paper presents an analysis of the hygrothermal performance of an inverted flat roof with a CLT (cross-laminated timber) structure in a building that meets the requirements of Passive House Standard (PHS) with regards to the potential risk of moisture. The calculations were made in the WUFI®Plus and WUFI®Bio software. The following variants were taken into account: three structure configurations, three different external climates and different scenarios of microclimate control and air change rate. The results of the calculations show that, especially in cooler climates, there is an actual moisture risk in the structure despite the excellent thermal insulation. The structure of the inverted flat roof, due to the use of a tight membrane on the outer side, allows for the partition to discharge the excess moisture only to the inside of the building. Ensuring the comfort of users may require periodic humidification of internal air, which translates directly into an increase in moisture content of the structure. The performed analysis clearly showed that there are no universal solutions. It is important to point out that for the proper performance of inverted wooden roofs, it is crucial to analyse moisture, not only thermal and energy parameters.

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Performance of smart vapor retarders under hot and humid summer conditions

Yoshinaga

2022

Building and Environment

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Advanced modelling of vapor resistance of moisture dependent vapor retarder

Cited by 3 publications

References 0 publications

Water Vapour Resistance of Ceiling Paints—Implications for the Use of Smart Vapour Barriers in Compact Wooden Roofs

Water Vapour Resistance of Ceiling Paints—Implications for the Use of Smart Vapour Barriers in Compact Wooden Roofs

Moisture Risk Analysis for Three Construction Variants of a Wooden Inverted Flat Roof

Performance of smart vapor retarders under hot and humid summer conditions

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