Hygrothermal performance of timber-framed walls in Turkey – Long-term monitoring

Abstract

The increasing energy consumption emphasizes the urgency of sustainable building practices. Worldwide, there is a tendency towards local, natural, durable, and recyclable materials like timber. Furthermore, timber's excellent thermal insulation and natural hygroscopic properties enable it to efficiently regulate indoor humidity levels, ensuring stability and comfort. In Turkey, timber construction declined significantly in the 20th century due to the shift towards vertical reinforced concrete, however, recent years have witnessed a renewed interest driven by earthquake concerns and global inclination. Despite this resurgence, timber construction practices are still limited, and the hygrothermal performance of exterior walls in both restoring traditional timber buildings and constructing new ones is often disregarded. Furthermore, there is a lack of scientific research in this area. Understanding the hygrothermal behaviour of these structures is essential for meeting modern energy efficiency standards. This study evaluates the hygrothermal performance of prevalent practices in timber-framed constructions in Turkey. Long-term monitoring in a full-scale test cabin exposed to real climatic effects provides insights. Findings indicate the exterior plywood sheathing on the North-west facing walls being more susceptible to moisture, particularly when the indoor relative humidity is elevated. South-east facing walls are better at drying, but air barrier membrane slows down drying. Timber cladding with ventilated cavity offers improved protection but its high exposure to rainfall in North-west, and solar radiation in South-east, implies potential performance degradation over time. Installing suitable vapour retarders and additional exterior thermal insulation particularly to the North-west facing walls could possibly reduce risks associated with moisture, as well as preventing thermal bridges.