Moisture control design has to respond to all relevant hygrothermal loads

Abstract

Moisture-related damage is still a formidable cost factor in the building sector. Besides installation deficiencies, moisture control design failures are the most frequent reasons for moisture problems. Therefore, adequate moisture control analysis has become the key for sustainable buildings. However, by only focusing on vapour diffusion other important moisture loads such as driving rain, construction moisture or air infiltration are mostly neglected. Therefore, international moisture control standards often refer to simulation models for more realistic analysis, leaving many practitioners wondering how to handle these tools. To overcome this dilemma, the updated German moisture control standard has introduced a three-pathway approach for design evaluation: first, deemed to satisfy list, second, restricted Glaser calculation and third, fully fledged hygrothermal simulation. The third pathway includes the option to account for small leaks or imperfections in building envelope components. Guidelines in other countries are also embracing similar moisture control approaches which gives hope for more durable and sustainable building design. To reach this aim, moisture control should also become an integral part of the design process instead of a secondary chore.