Insulation Boards – Comparing Performance with Efficiency

Not all areas in the home have the same levels of heat loss. Roughly a third of all energy is lost through leaky walls, windows and doors. Cavity walls in particular are major culprits. There’s lower, but still significant heat dissipation through poorly sealed ceilings, roofs and floors.

Insulation manufacturers tend to these issues with specially crafted boards for each part of your home. You’ll find boards for insulating cavity and external walls, boards for suspended and solid roofs, those that cater to slanted or flat roofs and insulation boards in various guises when sealing internal ceilings and exposed soffits. External masonry walls can additionally be sealed with insulated plasterboard.

The R-value, which indicates thermal resistance in a specific condition, is used to measure the insulating characteristics of boards. Higher R values mean lower energy losses and higher comfort levels throughout the year. Board thickness is also a factor here, with thicker boards naturally performing better.

That said, it’s best to go with trusted brands, like Kingspan insulation boards that state accurate R-values and give a further indication of expected cost-savings. Controlled production environments accurately specify moisture absorption levels (differentiating between boards for internal and external use), density, weight and most importantly, which core materials are used.

Having a basic understanding of the properties and differences in insulation panel boards means you’ll choose one type over another for your specific needs. Materials differ and boards vary greatly as to how effective they are in maintaining comfortable conditions while also keeping the effects of moisture to a minimum. Different production processes determine board rigidity and overall longevity.

Phenolic boards are a type of rigid foam insulation consisting of a closed-cell structure. They have some of the highest R-values of any insulation product currently on the market. Boards are heat, flame and water-resistant, hold their ground against mould, mildew and bacteria, have high density lending them favourable strength and rigidity, and retain their form and insulative performance for over 20 years.

These properties allow them to be optioned thinner, making them the perfect solution where space is limited. Ideal uses for these boards include roof, wall and floor applications.

PUR and PIR boards are closely related, using similar production processes and differing only slightly in insulative performance. Both are derived from closed-cell polyurethane foam and are lightweight, thermally efficient and recyclable. The differences lie in the blowing agent, lending to slight variations in cell structure.

PUR and PIR boards are often used in flat roofing insulation due to the high resistance to water absorption (and with added aluminium foil acting as a vapour barrier). They’re an inexpensive alternative to phenolic boards in wall and floor insulation, either on their own or bonded to plywood or OSB board. Their only downside compared to phenolic boards is their somewhat lower efficiency, meaning they need to be specced a bit thicker.

Polystyrene-based EPS (Extruded) and XPS (Expanded polystyrene) are older and cost-effective insulation solutions still in use today. Both closed-cell foam boards are extremely lightweight, have decent thermal properties, high heat, water and moisture resistance and very good durability.

EPS is favoured in flooring applications and insulating exterior walls where space is not an issue. It stands up to impact, and can also repel water if an adequate facer material is used.

XPS is a more affordable alternative to phenolic and PIR boards in roofing applications when sourced with metallic foils. To ease any doubts, both XPS and EPS boards meet current British Building Standards.

All boards above will meet the majority of customer needs. In addition, all have some level of acoustic insulation meaning they drone out irritable noises. Where they differ is in their thermal conductivity, fire ratings, and moisture absorption properties.

Phenolic boards fare best in all respects with the highest R-values, longest fire ratings and best performance in humid and wet conditions. That’s why they can be used in more applications and to better results. The higher price is negligent if you’re seeking the best insulation boards out there.

Stepping down means you’ll settle with slightly thicker PIR and PUR boards, though these too are more than adequate for most applications. If you’re looking for the cheapest option and insulating larger spaces, then EPS or XPS boards might be enough. Again, it all depends on what you need and where the boards will function.

This brings us to sizing in insulation boards. Most boards are 2400 by 1200mm and are installed vertically. Specific applications lead to different widths and heights, like roofing and wall cavity boards with 1200 by 450 and 1200 by 600mm, respectively.

More variation is found in thickness. The thinnest boards and those that are appropriate for tight spaces start out at 25mm, with different sizes going all the way to 150mm in the thickest floorboards and those found in external wall sheathing.

Set a budget and then source boards in the right materials and thickness for the project.