50 gallons weighs 245 kilograms, so it's going to have to be sturdy and the base of the construction needs to be spread over a wide area, otherwise your joists will sag and you'll get cracks appearing in the ceiling.
One trick is to centre it over an internal wall. Where two walls cross is ideal, that way the joists already crossing the wall at the top take all the strain and hardly move.
Nick from sunny Sale
March 2009
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