Insulation is vital in any building, as it helps maintain a comfortable temperature and reduces energy consumption. With the numerous types of insulation available, it can be challenging to know which one is best for your home or business. Two popular types of insulation are PUR and PIR, often used in walls, floors, and roofs.
What Are They?
PUR and PIR insulation is made from rigid foam and offers excellent thermal insulation. However, they have some fundamental differences worth understanding before deciding which one to use.
Polyurethane (PUR) insulation is made by mixing a two-part liquid of an isocyanate and a polyol. When these components mix, they react and expand to form a rigid foam with closed cells. PUR insulation has a low thermal conductivity, making it an excellent insulator. It is also lightweight and easy to install. It is often used in walls, roofs, and floors, as well as in refrigerated trucks and containers. PUR insulation typically has a thermal conductivity of around 0.022-0.027 W/mK.
Polyisocyanurate (PIR) insulation is a variation of PUR insulation modified to improve performance. PIR insulation is made by adding a third component to the two-part liquid that forms PUR insulation. The third component is a blowing agent, which helps to create a foam with smaller cells and a higher insulating value. This results in a foam with a lower thermal conductivity than PUR insulation. PIR insulation typically has a thermal conductivity of around 0.022 W/mK or less.
One of the main differences between PUR and PIR insulation is their thermal conductivity. PIR insulation has a lower thermal conductivity than PUR insulation, meaning it provides better insulation with a smaller thickness. It is particularly important in areas with limited space, such as roof spaces or cavity walls. For example, if you want to achieve a U-value of 0.18 W/m2K in a roof with a limited depth of 100mm, you need to use PIR insulation with a thermal conductivity of 0.022 W/mK. However, if you used PUR insulation with a thermal conductivity of 0.025 W/mK, you would need a depth of 120mm to achieve the same U-value.
Another difference between PUR and PIR insulation is their fire performance. PUR insulation is a highly flammable material and must be protected by a fire-resistant covering or used with other fire-resistant materials to meet building regulations. On the other hand, PIR insulation has a much better fire performance than PUR insulation and can be used in areas with higher fire risks without additional fire protection.
Durability is also a factor when choosing between PUR and PIR insulation. PIR insulation is more moisture-resistant than PUR insulation, which can absorb moisture over time and reduce its insulating properties. PIR insulation is less likely to degrade over time and can maintain its insulation performance for longer than PUR insulation.
In terms of cost, PIR insulation is generally more expensive than PUR insulation. It is due to the additional component added during the manufacturing process, which improves its insulating performance. However, the cost difference may be offset by the fact that PIR insulation requires less depth to achieve the same U-value as PUR insulation, reducing the overall material and labour costs.