Michi

I am making hot water tub from plywood and it was suggested that I put the tub in wooden frame put insulation around and encase in wood box Insulation is for two things- heat loss prevention and being in UK protecting the pipes from freezing. Tub will be resin coated with fiberglass layers My question is can I some how create a vacume chamber to encase the tub like hot water flask. Will that a bit to prevent heat loss' Thank you