Hygrothermal performance of timber frame walls with brick veneer cladding: a parameter analysis

¹ KU Leuven, Department of Civil Engineering, Building Physics Section, Kasteelpark Arenberg 40 – box 2447, BE-3001 Heverlee, Belgium
² UGent, Department of Environment, Laboratory of Wood Technology (UGent-Woodlab), Coupure Links 653, BE-9000 Gent, Belgium

^* Corresponding author: michiel.vanpachtenbeke@kuleuven.be

Abstract

To meet the increasingly stringent energy efficiency requirements, the market share of timber frame houses is steadily growing across Europe. Timber frame walls in Belgium are typically combined with a brick veneer cladding, which has a high buffer capacity for wind driven rain and a relative low cavity ventilation rate. Consequently, moisture levels inside the cavity may become high, which might lead to an inward vapour flow and an elevated moisture content in the inner part of the wall. In combination with a moisture sensitive timber frame inner wall, this could result in an increased risk of fungal growth. Therefore, the aim of the current paper is to study the hygrothermal performance of timber frame walls with brick veneer cladding in a moderate sea climate. To do so, a field study on two typical timber frame walls with brick veneer cladding is conducted. The field study specifically focuses on the contradictory criterion for the vapour diffusion resistance of the wind barrier for summer and winter conditions. The data of the in-situ measuring campaign indicates that the differences between set-ups with wind barriers with different vapour diffusion resistance is rather limited. In addition, a parameter analysis is conducted using a numerical model. The parameter analysis indicates an increased mould growth risk due to the brick veneer cladding and the importance of providing hygroscopic moisture buffer capacity inside the wall.