Spray applied foam insulation comes in two basic forms, "open cell" or (1/2 lb) and "closed cell" or (2 lb) there are some additional hybrid variations for specialist applications also. As the names suggest the main difference in the open or closed cell foam is structure of the cells within the cured foam. An open cell foam is of a density which is approximately 70% open, making it "permeable" or to quote the more commonly used phrase "breathable" and is best suited for timber structures such as roofing or stud work. This means the foam will absorb moisture and release it in the same way natural products such as timber will, which is necessary to maintain durability and structure.
Open cell foam is light, semi rigid and classified as a vapour retardant. When spray applied it will expand at a ratio of 1 - 100, thus creating a perfect airtight fit on any surface or in any hard to access space.
Closed cell foam is a more solid and rigid product, classified as a complete vapour barrier which means it is totally water resistant. It has an expansion ratio of 1 - 20 which allows it to maintain all contours and seal all joints on the surface to which it is applied.
It is best suited to metal structures such as commercial or agricultural buildings or in some cases it may be used as a base coat before finishing with open cell, to add rigidity and bonding to older roofing structures.
Page created : 15 | NOV | 2014