Influence of the Water Vapour Permeability of Airtight Sheets on the Behaviour of Facade

Joaquín Torres-Ramo, Purificación González-Martínez, Nerea Arriazu-Ramos and Ana Sánchez-Ostiz
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Joaquín Torres-Ramo: Department of Construction, School of Architecture, Building Services and Structures, University of Navarra (UNAV), Calle Universidad, 31009 Pamplona, Spain
Purificación González-Martínez: Department of Construction, School of Architecture, Building Services and Structures, University of Navarra (UNAV), Calle Universidad, 31009 Pamplona, Spain
Nerea Arriazu-Ramos: Department of Construction, School of Architecture, Building Services and Structures, University of Navarra (UNAV), Calle Universidad, 31009 Pamplona, Spain
Ana Sánchez-Ostiz: Department of Construction, School of Architecture, Building Services and Structures, University of Navarra (UNAV), Calle Universidad, 31009 Pamplona, Spain

Sustainability, 2020, vol. 12, issue 24, 1-18

Abstract: The air-tightness of the thermal envelope of buildings is one of the measures to reduce their energy demands in order to achieve global warming reduction targets. To this end, airtight sheets with different water vapour permeability characteristics are used. The different products studied are highly dispersed in terms of equivalent air thickness values, leading to confusion. After the analysis carried out, it is concluded that all airtight sheets are vapour barriers. To clarify whether or not these sheets are necessary as vapour barriers, a condensation analysis was carried out on 13 different facades for 3 climate zones with severe winters as defined in Spanish regulations. The results reveal that interstitial condensation occurs in only 7 of the 39 case studies, with the traditional facades of brickwork with render causing the greatest problems if the appropriate products are not used. In these cases, airtight sheets with water vapour barrier characteristics must be applied on the interior face of the insulating material. In all other cases (32), the airtight sheets must be permeable to water vapour if it is looked for a more breathable wall to water vapour and a better control of the interior humidity conditions.

Keywords: air-tightness; condensation; facades; vapour permeable; vapour barrier; equivalent air layer thickness (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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