THINK I'M GOING TO CRY

[38super]

HI All
I think I’m going to cry. I was just about ready to buy the Caldera Tahitian
when I wanted to double check the deck requirements . I had a Trex deck
built last year with the sole purpose of having a hot tub on it . I called the contractor
and had him look it over . He seemed unsure and was going to ck. ( was no question last year???) I went on Trex home page
and it stated it could be done BUT with extra consideration and planing what ever that means.
I read Trex is rated at 100 PSF with 16" on center . Everyone on this forum has been so helpful
with helping me find a tub and now this . I hope someone can help me . I’m sure I can do something with extra support but just about at my $$$$ limit. The Tahitian weights out at 4825 lb filled ....First question I guess is does anyone have a tub this large on a Trex deck ...............Thanks Will  

[Vinny]

From what I've been told the weight is mostly sitting on the joists not the decking. I believe you can put 1/4" plywood under the tub and as long as the joists are strong enough for the load it'll stay OK ...

[Brewman]

It should be more of a function of the deck support than the decking itself.
Joist size and beam size and spacing and footings all equate for load bearing.
Your decking itself should be fine, assuming your joists are 16" on center and your trex decking is perpindicular to the joists.  Some people install decking at a 45 degree angle to the joists, which can reduce the load somewhat.  
Could someone from your city or county building department look at your deck plans and see if the deck meets load requirements for a deck?  My city offers this service when building permits are applied for, which is required here for most deck construction.

[Brewman]

Your choice of decking was irrevalent because you stuck to the standards for joist spacing- if you wanted to space your joists 24" o.c., your choice of Trex decking would not be approved unless it was 2" thick product, or if you ran your decking at a 45 degree angle to the joists- you'd need to go 12"o.c. for the 5/4" material.
 Thinner decking needs closer spaced joists, and closer spaced joists, if properly sized and supported by adequately spaced and sized beams, which in turn are supported by adequately spaced footings, all equate to what load a deck will bear.

[sandiego]

people use trex all the time.....like others said it doesn't have as much  to do with the type of materials just getting proper support