Preservative treated timber outgassing

The BRANZ-led research project Preservative treated timber outgassing sought to better understand how some building materials – especially timber-based products – might release gases or chemicals into the air, a process known as outgassing (or offgassing). Volatile organic compounds (VOCs) are one group of chemicals that affect indoor air quality and can impact health. The study looked at VOC emissions from small samples of common construction materials, including glued laminated timber (glulam), plywood, laminated veneer lumber, and structural insulated panels, which are newer alternatives to traditional materials. It also tested different types of treated and untreated timber. The results showed that different materials release different types and amounts of VOCs. Some of these chemicals can be harmful to health, especially under certain conditions. In addition to potential health concerns, outgassing can damage nearby materials – for example, by causing corrosion or weakening of materials that aren’t compatible. To fully understand the risks, this testing needs to take place on a larger scale, testing materials behind typical wall linings and measuring how much of each VOC is released. This would help determine how serious the health or durability risks might be in real world homes and buildings.