What Is PIR Insulation? Everything You Need to Know

PIR is a widely-used shorthand term for 'polyisocyanurate', which provides us with one of the most thermally efficient commonly available insulation materials in the industry today. Like other organic materials, it is composed of complex hydrocarbon chains, and is classified as 'combustible'.

Polyisocyanurate (PIR) is a high-performance, polymer-based insulation material widely used in homes and buildings. Known for its exceptional thermal efficiency, PIR insulation boasts an impressive R-value range of 3.6 to 4.5 m²K/W, making it one of the most effective insulation solutions available.  

Derived from polyurethane, PIR offers superior insulation properties, including excellent flame resistance and long-term durability. Its high thermal performance and reliability make it a preferred choice for various residential and commercial insulation projects.  

But what exactly is PIR insulation, and why is it so effective? Let's explore its key benefits and applications.

What is PIR Insulation?  

PIR insulation, short for polyisocyanurate, is a highly efficient thermal insulation material. It shares the same base components as PUR (polyurethane) insulation but offers enhanced properties, including superior flame and smoke resistance, increased durability, and improved thermal efficiency.  

As one of the most thermally efficient insulation options available today, PIR insulation boasts an impressive R-value range of 3.6–4.5 m²K/W and exceptionally low thermal conductivity. Typically sold in the form of rigid boards or sheets, PIR insulation costs approximately £5–£15 per square meter, depending on thickness and specifications.  

While slightly more expensive than some alternative insulation materials, PIR insulation provides outstanding long-term benefits, making it a durable and cost-effective choice for home and commercial insulation projects.

What is PIR Insulation Used For?  

PIR insulation is commonly used for insulating internal and external walls, concrete floors, and loft spaces, particularly through roof rafters. It is also an effective solution for flat roofs but must be adequately covered to protect against sunlight and moisture damage.  

Due to the rigid structure of PIR boards, they are less suited for insulating areas with awkward angles, curves, or hard-to-reach spaces. However, they excel in flat, unobstructed areas, making them ideal for such applications.  

During installation, PIR boards can be easily cut to the required shapes and sizes. They are typically attached directly to the surface being insulated, along with a vapor barrier. The installation can then be completed with plasterwork or other covering materials for a clean, seamless finish.

What Are the Types of PIR Insulation?  

Polyisocyanurate (PIR) insulation materials are commonly available in rigid panels, sheets, and boards. These forms are quite similar, with the primary difference being their thickness, which typically ranges from 20mm to 200mm.  

Standard PIR insulation boards generally measure around 2.4m in length and 1.2m in width. Many of the panels, sheets, and boards available also feature a pre-bonded low-emissivity foil layer. This layer enhances thermal insulation and serves as a vapor barrier, offering added protection and efficiency.

Why is PIR Insulation so Expensive?

PIR insulation's notable performance comes with a higher price tag compared to alternatives. Several factors contribute to this cost disparity:

Manufacturing Complexity: The production of PIR is more complex and requires more energy than that of other insulations, demanding precise conditions and sophisticated technology.

Material Efficiency: PIR's higher thermal efficiency per thickness means less material is needed for equivalent insulation. However, this efficiency comes at a cost, influenced by the manufacturing complexities and material properties.

Fire Resistance and Durability: PIR generally exhibits better fire resistance and moisture resistance than other foam insulations, enhancing its durability and impacting its cost.

Market Dynamics: With stringent building codes and a push for energy efficiency, the demand for high-performance insulation like PIR is growing. However, supply chain issues and raw material availability can affect pricing.

Environmental Regulations: Compliance with environmental standards, particularly regarding chemical use in manufacturing, can increase production costs.

Logistics: PIR's rigidity necessitates careful handling and transportation, further adding to its cost.

Despite its higher initial expense, PIR insulation's benefits - superior thermal performance, durability, and fire resistance - justify its cost, offering long-term savings and performance advantages.

Can PIR Insulation Get Wet?  

While PIR insulation is inherently water-resistant, it is not completely immune to water damage. Like all insulation materials, prolonged exposure to moisture can lead to serious damage.  

To prevent such issues, it's essential to work with a professional installer who can identify and address any existing moisture problems and ensure proper installation. Additionally, creating adequate ventilation in the space can help maintain dryness in the event of a moisture breach.  

How Long Does PIR Insulation Last?  

PIR insulation is highly durable, with a lifespan of up to 50 years when properly maintained. This makes it one of the longest-lasting insulation materials available.  

It's advisable to assess the condition of your home insulation every 15 to 20 years to prevent potential issues. With regular care and inspection, PIR insulation can provide decades of comfort and efficiency in your home.

Pros and Cons of PIR Insulation  

PIR insulation is undoubtedly a highly effective choice for home insulation, but, like any material, it comes with both advantages and drawbacks. Let's start by exploring the pros:  

Excellent Thermal Performance: PIR insulation offers some of the best thermal retention properties among insulation materials, with an impressive R-value range of 3.6 - 4.5 m²K/W.  

Durability: The sturdy nature of PIR boards makes them highly resistant to weathering and aging, ensuring long-term reliability.  

Long-Lasting: With proper care, PIR insulation can last up to 50 years, providing lasting thermal comfort for your home.  

Great Safety Properties: PIR panel excels in smoke and flame resistance, as well as moisture resistance, making it a very safe material for installation.  

While PIR insulation offers numerous advantages, it's important to also consider its shortcomings to get a complete picture. Here are some key points to keep in mind:  

Environmentally Unsustainable: Polyisocyanurate is a synthetic polymer material that requires significant energy for production. It also releases harmful gases during manufacturing and is difficult to dispose of properly, raising concerns about its environmental impact.  

Limited Application: PIR insulation is almost entirely found in the form of rigid boards. This means that their application is limited to flat surface use, such as floors, walls and roof rafters. PIR insulation is not suitable for awkward angles and shapes.

Risk of Damage: PIR boards are vulnerable to sunlight and UV damage. Therefore, they must be properly protected from sun exposure, which can add to installation costs, especially for applications like external wall insulation.  

Given these pros and cons, it's clear that PIR insulation has its strengths but also certain limitations. The best approach to selecting home insulation is to consult with a professional installer or insulation company to find the most suitable option for your specific needs.