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The way that tub was set up on blocks like that, it would have failed with ANY structure I'm sure.Steve
One concern I have with metal frames...Do they buy 8' lengths and then cut them? If so the ends would no longer be galvanized and would rust.
the potential for a spa to collapse set on blocks like that is there whether it's wood or metal. in any case the metal framed spa and even wood framed spas are engineered to support that much weight up in the air with for small points such as blocks in just the corners holding all that weight. on lower blocks with some type of support in the middle, or even just support under the footwell, imo it's doubtful that would have occured. is it also possible the structure of the spa shell contributed to this collapse? maybe, maybe not.