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The difference between open-cell and closed-cell spray foam


Both open-cell and closed-cell spray foam insulation will insulate your home or commercial business, however, there are differences that mean they suit different applications.

Closed-cell spray foam

Closed-cell spray foam is the more common of the two types of polyurethane spray foam, and, as the name suggests, the cells are completely closed. This makes it more dense, rigid, waterproof and gives it a higher R-value per inch (insulation) when compared with open-cell spray foam. Here is a breakdown of the characteristics of closed-cell spray foam:

  • Rigid and strong
  • R-value of 6.0 per inch or higher
  • Prevents draughts
  • Waterproof
  • Prevents mould growth
  • Provides good support for walls
  • Expands around 1 inch of thickness when sprayed

Open-cell spray foam

Alternatively, open-cell foam is made up of cells which are not completely closed; this makes open-cell spray foam more flexible – it is also more affordable than closed-cell spray foam. Here is a breakdown of the characteristics of open-cell spray foam:

  • R-value of around 3.8 per inch
  • Permeable – allows the transfer of water and air
  • Less support for walls
  • More affordable
  • Expands around 3 inches of thickness when sprayed

Which spray foam insultation should I choose?

So, you now know the characteristics of each type of spray foam insulation, but which one is right for you? The spray foam insulation you choose will depend on the location of installation and other factors.

For example, if you have the budget and are looking for the best insulation possible that is also waterproof, then closed-cell insulation will be your best bet. However, if you have a lower budget, live in an overall mild climate, or are undertaking a small fill-in for a difficult to access place, then open-cell spray foam will do the job just fine.

If you need any further advice when it comes to spray foam insulation, don't hesitate to contact our spray foam experts. We install high quality spray foam insulation for clients across London, the Midlands and the South!