Do You Need a Vapor Barrier With Spray Foam Insulation?

One of the most frequent questions we’re asked about spray foam insulation is whether you also need a vapour barrier. The answer can differ and depends on the type of spray foam you use and where your property is located. Mass Foam Systems are UK based and specialise in Icynene® spray foam insulation. We use Icynene® insulation over polyurethane as we find it to be a more superior product. A vapour barrier is not necessary with closed-cell foam but with open-cell spray foam such as Icynene®, it is sometimes required.

Any air that migrates though a building envelope will carry water vapour. As Icynene® spray foam creates a seamless air-seal, it controls air leakage and the moisture in the air. It is also vapour permeable, so any moisture in the property can escape through the insulation as it dries out.

It’s worth pointing out that Icynene® isn’t a vapour barrier and local product certifications and building regulations must be followed. In many parts of the UK, the installation of a vapour barrier isn’t needed unless required by local certification. However, each property will need to be assessed on a case by case basis to determine this. This decision is affected by local climate and elements within the building envelope

What if I need a vapour barrier?

If a vapour barrier is required, this can be applied quickly. One of the simplest options is to use a vapour retarder paint. This can be sprayed onto the surface of the Icynene® spray foam insulation or on the surface of the drywall.

Mass Foam Systems are the UK’s leading Icynene® spray foam insulation company and we are proud to have a 100% satisfaction rate. Our company was established five years ago, and we are experts in the spray foam insulation industry. If you’re unsure whether your property requires a vapour barrier or you’d like more information on our spray foam services, either request a call back or speak to us directly on 0800 246 5051.

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