How to buy insulation boards

Insulating your home well is essential to maintaining pleasant temperatures and ensuring energy efficiency. Insulation boards can be a great solution for insulating roofs, floors and walls, with an array of options. 

Confused by the difference between PIR and PUR, or EPS and XPS? 

Read on to find out the strengths of various insulation boards, where to buy them and how they are best applied around the home.

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What is insulation board?

Insulation boards are rigid boards or sheets made of foamed polystyrene, polyurethane, polyisocyanurate, or gypsum. 

Their rigid, closed-cell structures provide better insulation compared to traditional wool insulation.

They can be used to insulate a roof, wall or floor, and prevent heat from escaping the property.

Three key benefits of using insulation board are:

• They achieve reduce heat loss more efficiently than wool insulation, whilst also taking up less space
• Insulation board is light, easy to install and doesn’t need maintenance once in place
• Harmful fibres are not released, which can happen with fibreglass insulation

If you aren’t sure where to start with improving your insulation, read our guide to how to insulate your home.

Types of insulation board

PIR (Polyisocyanurate)

• A rigid foam board that is durable and has a high fire safety value
• Has the best thermal efficiency, ensuring that heat stays inside your property
• Versatile - can insulate roofs, walls and floors
• Come with foil backing that acts as a moisture barrier and reflects heat

PUR (Polyurethane)

• Lighter and cheaper than PIR, but with slightly less thermal efficiency
• Due to this, a thicker layer may be needed
• Versatile - can insulate roofs, walls and floors
• Is also an effective moisture barrier, but has less smoke and flame resistance than PIR boards

EPS (expanded polystyrene insulation)

• Lightweight and easy to use, this is a very common type of insulation board
• Ideal for insulating walls and roofs
• Made by expanding foam beads in a mould where they fuse together and fill with air, resulting in the lightness
• EPS is less resistant to water vapour than XPS, so less useful for insulating humid areas

XPS (extruded polystyrene insulation)

• Structure prevents water penetrating the board, giving long term strength and durability
• Can be used to insulate basements, roofs, facades and cavity walls
• Has the best compressive strength of these materials so is under slabs, concrete floors, foundations and underground works
• Cheaper than PIR and PUR but more expensive than EPS

Insulated plasterboards

• Also known as drywall, plasterboards are made from gypsum, a soft  mineral form of calcium sulphate dihydrate. 
• An insulating material such as PIR or polystyrene is added to standard plasterboard
• Lightweight and easy to fit, it combines insulation and drylining to save space and improve thermal efficiency

Soundproofing insulation boards

If you’re looking to prevent sound from escaping alongside heat, these are some effective types of insulation that can be installed in the walls, in the form of boards:

• Mineral wool
• Glass mineral wool
• Soundproof insulation mats

Alongside fitting insulation boards and other insulating materials, consider our advice on how to draughtproof your home to further prevent heat escaping.

Where to buy insulation board

As there are a huge variety of types of insulation board, and for each time a range of styles and thicknesses, this table is not an exhaustive list of available retailers or products. 

However, it should give you an indication of what to look for, some of the shops and brands that are available, and how much you might expect to pay for different materials and sizes. 

Floor insulation board

Expanded or extruded polystyrene insulation boards are best suited for floor insulation. As they will be installed underneath the supporting floor, the boards need good compressive strength to handle heavy loads without breaking. 

The heat-loss impact of polystyrene boards is slightly less than plastic variants, so a thicker layer of boards may be needed. 

For more details on how to insulate your flooring read our guide to floor insulation options and cost.

Wall insulation board

PIR or polystyrene insulation boards are both suitable for insulating walls. If you have a stud wall, PIR boards are likely to be the better option.

For internal walls, you can try using insulated plasterboards for a lightweight, effective barrier to block heat disappearing from different rooms.

Find out everything you need to know about insulating different types of walls in our guides to cavity wall insulation and cavity wall insulation costs and savings.

Roof insulation board

Insulation board can be used for both pitched and flat roofs. Once cut to size, they are placed either above or under the roof rafters or between ceiling joists, creating a barrier in any space where heat can be lost.

The best type of insulation boards to use in a roof are PIR, but PUR could be used for flat roofs. Alternatively, try lightweight insulated plasterboards.

Our roof insulation types explained article will tell you the difference between insulating a pitched roof and a flat roof, and whether you should install cold or warm loft insulation.

Can I install insulation board myself?

If you are a confident DIYer and have a few tools and skills, it may be possible to install insulation board yourself. 

There are two common methods used to fit insulation boards:

• Dot and dab - the insulation board is bonded directly to a wall
• Batten - the boards are attached to wooden frame battens to make a gap between the wall and the insulation

If for peace of mind you’d rather hire a professional, you can use our Which? Trusted Trader tool to find a reliable trader near you:

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