I want to put a hot tube on my deck and I need to know what size beam and posts to use?
Question:The hot tub is 7'6" x 7.5' square and has a filled weight of 4000 lbs. I figure I would add another 1000 lbs. for people weight for a total of 5000 lbs. live load. 5000 / (7.5 • 7.5) = 88.9 lbs. per square foot. Plus dead load of 15 psf, and I end up with a total of 104 psf which I need to support.
The deck joists will be pressure treated 2x6 place on 16" centers and the top decking material will be 2x6's placed flat on the joists and screwed down with 3" deck screws.
What I need to find out is what size beams should I use and how far should I space out my post holes. I want to use pressure treated 4x4 for my posts, placed on concrete pier blocks that will be cemented into my post holes.. I think I have everything covered except how to calculate my beam size, spans and spacing.
Answers:
Just went thru the same thing and to cover that weight, btw mine came in at 4124 lbs I followed Lowes Deck building guide..you are on the right track
http://www.lowes.com/lowes/lkn?action=ho...
Also keep in mind that you will need a 60 Amp gfci circuit to the hot tub w/3 wire #6 THHN...that will be three wires plus a ground.good luck to you..its a fun project
Your dealing with a lot of weight and in my opinion should consult a structural engineer. They can help you with the structural design and size the beams. They could also point out other issues that you might not have thought of. If you don't know of any, contact a local engineering firm or an architectural firm. They will be able to either help you directly or point you in the right direction. This will obviously incur a fee but doing it right the first time will be less expensive than fixing a problem down the road if it's done incorrectly.
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