PIR Insulation: What It Is and When to Use It
What is PIR insulation?
PIR insulation boards, short for polyisocyanurate, are among the most efficient rigid insulation materials used in construction today. They offer high thermal performance despite their relatively thin profile, making them particularly suitable for renovation projects where space is limited. At Dromenbouw, PIR is regularly used for attic floors, interior roof insulation, and upgrading existing floors.
PIR insulation is a rigid foam board that is usually finished with an aluminum facing on both sides. This aluminum layer enhances the insulating properties and helps control moisture. The thermal conductivity coefficient is typically between 0.022 and 0.026 W/mK, meaning that even a relatively thin panel achieves a high insulation value. The material is lightweight, yet strong and resistant to compression. It is also moisture-resistant and easy to cut to size and install.
Thanks to these properties, thinner PIR boards can achieve insulation values comparable to those of significantly thicker layers of mineral wool.
Why choose PIR over mineral wool?
Both PIR and mineral wool have their uses in construction. However, PIR is particularly advantageous when construction depth is limited or when a high R-value is required with minimal thickness. This is often the case in renovation projects, flat roofs, and floor insulation.
By way of comparison, approximately 100 millimeters of PIR insulation can provide thermal performance comparable to that of approximately 160 millimeters of mineral wool, depending on the exact product specifications. This means that high energy performance can still be achieved with a thinner insulation layer.
Applications of PIR insulation
PIR is commonly used for attic floor insulation when the attic is not used as living space. Insulating the floor helps retain heat in the living areas below.
When insulating a roof from the inside, PIR is often installed between or under the rafters, provided that a vapor barrier and an airtight finish are properly installed. This is essential to prevent condensation problems.
In addition, thanks to its high compressive strength, PIR is ideal for concrete floors and applications under screeds. The material remains stable under load and retains its insulating properties.
Common mistakes during installation
Despite the high quality of the material, improper installation can significantly reduce its performance. Gaps between the panels cause heat loss and must always be carefully sealed and taped. Joints where the panels meet beams and walls require special attention, as thermal bridges often form there.
A proper vapor control strategy is also essential. Depending on the existing structure, a vapor barrier or airtight finish may be necessary. Furthermore, PIR must always be part of a well-designed insulation system and should not be combined with other materials without a technical plan.
How thick should PIR be?
The required thickness depends on the existing structure, the R-value required by Dutch building codes, the type of renovation, and the available space. For floor renovations, two layers ranging from 40 to 60 millimeters are often used. For roof insulation, thicknesses of 80 to 120 millimeters or more are typically used.
A thorough preliminary inspection remains essential for determining the right solution.
Is PIR a good investment?
When PIR is installed correctly, it offers clear benefits. It reduces heat loss, improves living comfort, lowers energy costs, and can increase the value of your home. However, professional installation is essential to prevent condensation problems and thermal bridges.
Final Recommendations from Dromenbouw
Insulation involves more than just installing panels. It’s about creating a comprehensive, high-performance system in which the structure, vapor barrier, and finish are perfectly coordinated.
If you are considering PIR insulation for your attic or floor renovation, proper planning and installation are crucial for a long-lasting result.
If you'd like advice on your project, visit dromenbouw.nl and request a consultation.