Expert: Dan Griffin - 3/25/2009

Question
Hi, I am about to put a 70 Gallon Aquarium in my bedroom on the 1st floor in a standard detached residential home (from UK not sure how much difference there is in building strength between the US and UK) built in the 1970's or 80's not to sure. It is a corner unit and will be in the corner next to an outer bearing wall and inner partition wall covering at least 2 joists maybe just resting over a 3rd not checked just yet. (don't know the type of wood but if its the same as in the attic then its bloody hard)the room is about 10ft x 10ft. the tank base unit has a flat base so the weight is evenly distributed. The Tank fully filled + rocks + the weight of the tank and stand combined is 800-850 pounds and the dimensions are 122cm in width 87cm in depth ( http://www.pondsdelivered.co.uk/catalog/fluval-venezia-350-corner-aquarium-and-c... ) <Link to look at shape and dimensions if needed. it is like a quarter of a circle shape with rounded front so not flat. 800 pounds just doesnt seem like alot of weight for a floor to hold but picking up one 5 gallon container of salt water made me think twice. looking around it seems like the floor will hold but could possibly weaken over a long period of time? just want to be safe really.

Thanks, Mike.

Answer
Michael, after a bit of translating it looks as if you're putting 800 pounds on about a 12 sq. ft. footprint.  That would make the load about 66 #/SF.  US code on recent construction would be good for 40#/SF so you are pushing the limits.  The saving grace would be if you are sitting on the joist tails where they sit on the outside wall.  This would be a bit like 4 big men standing shoulder to shoulder in the corner, probably not a problem.