Timber has long been a staple construction material for domestic scale properties, although it is increasingly being used in high-profile structures such as the Weald & Downland Gridshell. However, exposure to the elements can result in changes to the chemical and physical properties of wood, affecting its aesthetics, structure and longevity.

This programme takes a look at different forms of weathering – from UV radiation and wind, through to rainfall, ice and snow – and their impact upon different forms of wood. It discusses the bleaching effect of sunlight in relation to softwoods and hardwoods, dark timbers and light timbers, and with reference to individual species of tree. The effect of wood moisture content on weathering is explained, while the relative merits of paints, varnishes and wood stains as preservatives are examined. It also looks at the aesthetic pros and cons of timber weathering.