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deck structure

I need to build a deck to support a hot tub. They say it needs to support 125# per square foot. What size joists do I need to use, and how far apart?

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Posted 2011-10-16T21:47:33+0000  by Tigger Tigger

Can you provide more information about your proposed deck? How big is the deck, how far off the ground, is it on a slope, single level or multilevel, free-standing or attached, type of material (cedar/redwood/ipe, pressure treated, composite, pvc), size of the hot tub, placement on the deck, etc? Don't be stingy with the info, the more the better.

Posted 2011-10-17T02:42:36+0000  by Paul

My deck is about 3-4' off the ground, with no slope. It will be 12' across in both directions and an octagon on 5 sides with one squared off corner.


        l                                           \      roughly like this:

        l                                             \

        l                                               \       

        l                                                 \        I will be using 4*4 posts,

        l                                                  l       PT joists, 2*6 cedar

        l                                                  l       decking.

        l                                                  l       This deck is attached to

        l                                                  l         the main deck on the

         \                                                /           front side, and it is one

          \                                              /           step up.

            \                                           /                                               

              \ ___________________/          The hot tub is 7' square,

                                                                   located in the center of

                                                                  the deck.


                                                                 Hope this helps!



Posted 2011-10-17T09:06:41+0000  by Tigger


Hi Tiger, this is Mike The Home Depot Answer Man


The structure of your deck is dependent upon a number of factors. 


The first step is to contact your local building department. Each city has a different set of building regulations and permit requirements. Make sure you meet the cities' requirements or an expensive rebuild may be in order.


Secondly, contact the manufacture of the hot tub to determine their requirements for the size of the deck and the construction they recommend.


Once you have determined the cities’ requirements and the recommendations of the manufacturer, the next step is to determine which materials are best suited for your area and budget.


Check out our” Decks 123” guide at your local Home Depot. It’s a volume chock full of the information on deck materials, the tools you’ll need and includes construction tips and techniques.


Finally check out other decks in your neighborhood, this will give you some good ideas of what’s popular in your area.


I hope this information is useful to you.




Posted 2011-10-18T00:50:22+0000  by Mike_HD_OC

Another thing you will need to find out is the weight of the tub, filled and with the maximum number of people in it. For a typical acrylic/fiberglass tub, you're probably looking at around 600 gallons of water at 8lbs/gallon. For a wood tub you can safely double that due to less interior water displacing features. With six people at 200 lbs each. That would mean you have to account for a load of 6000 lbs to 10,800 lbs. The manufacturer should be able to provide this information.

Posted 2011-10-18T22:00:46+0000  by Paul

Welcome to the How-To-Community Tigger.


My name is George and I just wanted to add something to the already great info given from Paul and Mike.


Tigger I’m not sure if you’re aware but in our stores we have a deck design program available for convenience of our customers free of charge. If you provide us with your complete deck measurements and tub specs, we can design your deck changing the standard dead load and live load assigned in the system (usually 40lbs per SF) to the one equivalent to the load of the tub per square foot.


Last time I checked we can bump up dead load up to 120 lbs per SF.


Please see our Pro Desk Department for assistance with the deck design.


Now there is something else I wanted to suggest …Have you consider building a deck up around the tub, with the spa itself sitting on the ground level?


You can pour concrete slab with footers underneath the tub and not have to worry about the deck supports.

Another advantage of having tub sit on the ground level is that you can lower your tub down, save some money on concrete and tub accessories and at the same time achieve convenient tub entry height.

Hot Tub.JPG


But again like Mike said run everything you’re about to do by your local building department including proposed deck design which from my experience should be satisfactory towards obtaining a permit.


Hope this helps and good luck with your project.



Posted 2011-10-25T14:36:14+0000  by George_HD_CHI
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