hot-tub on an exterior deck

huangyhg

hot-tub on an exterior deck
does anybody have any experience in designing a deck attached to an existing house, which needs to support a hot-tub?  i have asked the arch. for footprint and weight when the hot-tub is full.  are there any specific requirements for supporting that kind of load?  (i'm thinking i may need to use double wood joists depending on the load)
i'd imagine hot tubs vary in depth from manufacturer to manufacturer, but 2 feet of water will put a load of 124.8 psf.  you'll find you'll need quite a stout deck.
we have an 8-ft hot tub in our deck, but it's actually being supported by a concrete pad.
ttfn
yes, let it sit on a concrete pad.
if you need to use wood, it is possible. you need to check shear stress and make sure that the hangers are adequate.
yes i have.
always the tub manufacture has provided the weight of the tub full of water and with the weight of the number of people the tub will accomodate.  they usually use 200# per person.  the deck indeed has to be stout.  re  
if the tub is 8 foot square, the heaviest ones (cal spa) are just under 1500 pounds, and no more than 500 gallons.
the southernpine site has span tables for 150 lbs/ft joists:
if the deck is too high to support the tub with a slab, analyze the deck framing with the hot tub in the worst places possible for each   
my wife wanted to put a pool on my elevated wood deck so i checked the deck for what it would support. it will only support 6 inches of water before it, theoretically, is unsafe.
the critical element to check is probably the joist support to the house. install some simpson hangers if you don't have them already. either way, if it's a typical residential deck, it will not support the weight of a hot tub without some retrofit.
thank you all for the very helpful comments.  i did get in contact with a local hot-tub supplier and it seems that they typcially put the tub on a slab on grade and build the deck around the tub to suit.  these units are self contained and they are filled and drained with a garden hose, so therefore there are no potential problems with piping, etc. from shifting of the tub.  if it did move around too much, the only problem would be the water level would tell you how crooked the tub actually is. (or how crooked they built it!)
incidentally, the standard tubs around here are 7'x7'x37" high, with 345 gallons of water and 5-6 persons.  self weight of tub is around 500-600 lbs and total weight is a bit over 4000 pounds - way too much for a typcial wood deck. (especially when you throw in the reductions for wet service, pressure treated, etc)
hmmm,
it depends on the builder, i.e. how well it is framed.  i have one on a wood deck, and it's performing fine.  i'll be replacing the wood in a few years (since it was built in 1996), but it shows no signs of distress.  (it's about 6 feet off the ground - on dolomitic limestone.  i can get close to the supports without much trouble.)  the deck is in better shape than the spa, incidentally -
i have done them both ways....supported by the framing and on a slab.  it really was a function of the size (and therefore the loading) on the tub.  
if you do support it on the deck...using galvanized joist hangers (or stainless steel) is critical since the tub will have some chlorine in the water and will corrode the steel for the hangers.