With energy bills at record highs, now is the time to insulate your home, office, or business. There are dozens of insulation materials to choose from, but virtually all keep interiors warmer during the winter and cooler in the summer. 

Insulation boards are the most popular due to their high efficiency, simple installation, and the fact that they’re versatile and can be used on walls, roofs, and floors. What’s more, they pay themselves off within a couple of years, as you’ll be saving on gas and electricity, especially when the cold hits.

Thermal Insulation Boards: The Basics

Thermal Insulation Boards

Insulation boards are rigid, dense panels made of closed-cell plastic foams. The material consists largely of air trapped in a closed cell construction, which proves highly efficient against heat loss. 

Moreover, boards are very effective in sealing gaps and closing air leaks, so you’ll be using considerably less energy to cool or warm rooms and interiors. Other benefits are that they are very good against moisture, so they prevent mould and mildew, and they lend structural rigidity to the building elements with which they are used.

The main reason to go with boards is that they have some of the highest R-values, or thermal efficiency, of any type of insulation material, including traditional options like batts and spray foam. And they are easier and cheaper to install, meaning you can thoroughly insulate your home with a few basic tools and on your own. 

Types of Rigid Foam Insulation Boards

Rigid insulation boards have existed since the 1950s with Expanded Polystyrene (EPS) and Extruded Polystyrene (XPS) seeing extensive use in the post-war building boom. The materials are seen even today and are some of the more cost-effective options, particularly effective in flooring applications due to their high compressive strength. 

While both polystyrene-based boards have decent R-values for the price, other properties, such as susceptibility to water absorption in EPS or the high content of potentially toxic materials in XPS and lower recyclability have led to other, more efficient products. Polyurethane-based boards PUR and PIR have largely replaced older EPS and XPS boards for insulation purposes. They contain a higher polymer content in the overall product, a more densely packed closed cell structure, and are often sold with aluminium backing acting as a moisture barrier and fire retardant. 

The main selling point though, particularly for newer PIR insulation boards, is that they have much higher thermal efficiency, meaning more warmth in winter, cooler summers, and significantly lower bills. The boards can also be used in thinner variants, with types like 75mm PIR insulation boards showing their worth in tighter spaces. 

Why Choose PIR Insulation Boards?

Why Choose PIR Insulation Boards

PIR insulation boards have many benefits over other rigid insulation boards. Possibly the first and most important is the price. Since they have become widely available, prices have significantly come down when compared to PUR, EPS, and XPS boards. 

They can also be optioned much thinner. And thickness is another factor that determines the price. For instance, to retain the same thermal efficiency ratings of a 75mm PIR insulation board, a competing XPS board needs to be almost twice as thick, or 150mm. 

But the PIR boards will cost less and the savings add up in bigger insulation projects. And they can be installed in places (such as above concrete floors) where thicker boards possibly can’t fit without going against current building regulations and encroaching on recommended ceiling heights. 

Compared to PUR boards, the higher concentration of blowing agents in the production of the boards leads to a slightly different structure and makes PIR boards denser, stronger, and more fire-resistant. If you’re looking for ultimate rigidity and boards with some of the highest fire ratings, go with PIR. Furthermore, the boards won’t rot over time, deform, or attract vermin. 

The advantages don’t end there though. PIR has comparable impact resistance and compressive strength to XPS, making it ideal for flooring uses, works well against moisture and humidity, so good for roofing and external wall applications (albeit with insulated plasterboard), and unlike other boards and insulation materials is completely eco-friendly (no CFCs like PUR) and recyclable. 

Where Can I Use PIR Boards?

Where Can I Use PIR Boards

The favourable properties make this an insulative material that can be used virtually anywhere. You can find PIR boards in all types of walls (cavity, solid and external), on their own or in combination with phenolic boards or insulated plasterboard. They’re additionally seen in roofing, and good for both slanted and flat roofs, as well as ceilings and lofts. 

Lastly, PIR insulation boards are also extensively used to retain heat escaping through solid concrete, stone and suspended timber floors. When sourcing PIR boards for your project, insulation manufacturers make it easier by defining where each board can be used and will specify the recommended thicknesses. 

Buying and Installation

To get the best thermal properties in any insulation board, go with the highest thickness the project and your budget allows. PIR boards can be sourced in varying thicknesses, ranging from an extra-thin 25mm to 150mm variants when there’s the need for the highest R-values. 

Between these two extremes are boards in medium thickness and which see the most use for the majority of insulation jobs. As an example, most cavity walls use boards between 60 and 100mm, with 75mm PIR insulation as the most common size. Roofing projects often require thicker boards, while there’s more leeway in different floor types due to the available space. 

Transporting and installation of PIR insulation is simple. Boards are exceptionally light and come in standard building sizes of 2400mm by 1200mm for most uses. Roofing projects require 1200mm by 1200mm or 600 by 600mm. 

Installation is simple even for anyone not handy with tools. You’ll need boards of the right thickness, a saw or utility knife to cut the boards to shape, measuring tape for a snug fit, and depending on the application, a bonding agent, adhesive, and trowel to prevent air gaps. Boards can be used with fasteners when fixing them to existing metal or timber framing or you can purchase separate fixings and hardware for other areas. Go with respected local brands to ensure you get the best quality. 


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