Temperatures are rising. Here is why wood fibre insulation should be your first choice in your new build or extension.

Wood fibre insulation and PIR (polyisocyanurate) are two different insulation materials, each with its own set of properties and advantages. When considering the aspect of overheating, wood fibre insulation offers some specific benefits:

1. Hygroscopic Properties:

   • Wood Fibre: One of the primary advantages of wood fibre insulation is its hygroscopic nature, meaning it can absorb and release moisture without compromising its insulative properties. This moisture-regulating ability helps moderate indoor humidity levels and can reduce the risk of condensation within building elements.

   • PIR: PIR, being a synthetic material, doesn't have the same moisture-regulating properties as wood fibre.

2. Thermal Mass:

   • Wood Fibre: Wood fibre insulation contributes to the thermal mass of a building. Materials with higher thermal mass can absorb, store, and slowly release heat, which helps buffer temperature swings and reduces peak temperatures inside the building. This can be particularly advantageous in preventing overheating during summer months.

   • PIR: PIR insulation is lightweight and doesn't contribute much to the thermal mass of a structure, so it can't help moderate temperature swings as effectively as wood fibre.

3. Vapor Permeability:

   • Wood Fibre: This insulation is vapor permeable, which promotes a breathable building envelope. This allows water vapor to diffuse through the structure, reducing the risk of moisture-related issues.

   • PIR: PIR panels are generally less permeable to vapor, which means careful detailing is required to manage moisture and prevent potential condensation problems.

4. Environmental and Health Benefits:

   • Wood Fibre: Being a natural material, wood fibre has a lower embodied energy and a smaller carbon footprint compared to many synthetic insulations. It's also free from harmful chemicals and is fully recyclable or compostable at the end of its life.

   • PIR: PIR is a petroleum-based product and typically has a higher embodied energy. There are also concerns about blowing agents used in its production, which may have global warming potential.

5. Sound Insulation:

   • Wood Fibre: Wood fibre boards can provide good sound insulation due to their density and fibrous structure, offering an added benefit in terms of acoustic performance.

   • PIR: While PIR can provide some sound insulation, it's generally not as effective as denser materials like wood fibre.

6. Fire Performance:

   • Wood Fibre: Wood fibre generally has good fire-resistant properties and will char rather than melt, slowing the spread of flames.

   • PIR: PIR boards are usually treated to be fire-resistant, but they can release toxic fumes when burned.

In summary, in the context of overheating, wood fibre insulation's contribution to thermal mass and its hygroscopic properties make it particularly suitable for moderating indoor temperatures and providing a more stable and comfortable internal environment, especially during hotter periods. It's also beneficial in terms of moisture management, environmental considerations, and acoustic performance. However, the choice between wood fibre and PIR should also consider other factors such as cost, availability, and specific project requirements.