The optional full-foam insulation offered in South Seas Spas provides the most efficient heat retention available in any spa on the market. It dramatically increases the strength and life of the spa’s shell. The Icynene brand of full foam secures plumbing to the shell for longer plumbing life and conforms to all curves and spaces to provide a seamless air barrier. Increasing the durability of the structure, the foam provides consistent R-value to the spa. Icynene foam does not absorb water or allow mass transfer that may cause mould. It does allow moisture present in the structure to escape in the form of water vapour enabling complete drying.