Why Do We Use Wood Fibre Insulation? – Can I Just Ask? | Ep.17

The case for wood fibre insulation rests on three broad pillars: environmental credentials, building performance, and practical usability. From an environmental standpoint, wood fibre is manufactured from waste timber, stores carbon within the building fabric, and represents a far less energy-intensive option than most conventional insulation materials. These qualities have made it increasingly prominent as the industry grapples with embodied carbon, but as the discussion in this episode makes clear, the environmental argument is almost secondary to the performance one.

On performance, wood fibre’s combination of properties sets it apart from lightweight synthetic alternatives. Its high specific heat capacity gives it significant thermal mass, which is increasingly valuable in a climate where summer overheating is a growing concern — slowing the movement of heat through the fabric and shifting peak internal temperatures well beyond peak external ones. It’s also highly vapour permeable, buffering moisture rather than trapping it, which makes it inherently more tolerant of real-world installation conditions and reduces the risk of moisture accumulation over time. Two constructions might achieve identical U-values on paper, but the phase shift and moisture behaviour of a dense wood fibre build-up compared to a lightweight, low-conductivity insulation are in a different league.

The third dimension is practical — and often underappreciated. Wood fibre is friction-fitted, dense enough to fill cavities without gaps, and straightforward to work with on site, which directly reduces the performance gap between design intent and what’s actually achieved in the build. It’s also non-toxic for both installers and occupants over the long term. The conclusion drawn here is a simple one: wood fibre is specified primarily because it is the most pragmatic, high-performing material available for these roles — the environmental benefits are real, but they’re increasingly just a bonus on top.