Types of spray foam

Open Cell Spray Foam

Great acoustic qualities and very good thermal values. As the name suggests, it expands at a rate of 1:100 times its volume and allows water vapour to pass through. Open cell foam is generally used in attic, under floor and roof insulation where water vapour needs to exit the structure.

Closed Cell Spray Foam

Expands at a rate of 1:25 times its volume and is more compact and rigid. Typically used for all commercial applications, such as warehousing, workshops, men sheds and concrete applications.
It is also used in roof applications (internal or external), encapsulates asbestos fibres, stops condensation and stops vermin.
There are various densities of closed cell foam, a standard closed cell foam is 35kgsm3, where exterior roofing foam is 50kgm3 (where it is so rigid that it can be walked on).