How Do I Know If my Deck Can Support a Hot Tub?  

The quick answer to the question in the title is your wood or composite deck cannot support a hot tub without modifications. If we assume that your deck was originally built to code, depending on your jurisdiction, most building codes are require that a deck be able to support roughly 40 pounds per square foot.

Most people don’t realize that a hot tub filled with water and people may weigh several thousand pounds. That’s a far cry from what your deck was designed to support. Let’s take a closer look at hot tub weight.

How much does a hot tub weigh?

For the sake of discussion, a modest hot tub that measures about five feet square could weigh approximately 750 pounds all by itself. Then fill it with water, and the water alone may weigh about 1000 pounds because water weighs about eight pounds per gallon. Then add three people at 150 pounds each, and that is an additional 450 pounds.

If you add that all up, you now have 750 + 1000 + 450 = 2200 pounds. That is 2200 pounds spread out over 25 square feet, or the original footprint of the hot tub which equals about 90 pounds per square foot or more than twice what your deck was designed for by code.

With a larger hot tub, the pounds per square foot could be several multiples of that. We have used conservative round numbers for estimates. Water is extremely heavy, and that is why even putting a large 100- or 200-gallon aquarium in your house requires some calculations to determine if floor joists can support it.

If you want to have a hot tub on your deck, the deck will have to be modified to support it.

Deck Experts, based in Surrey, BC, are professional deck builders with a long track record of success. We offer free estimates and long warranties and can build or fix any deck around. If you have any questions about this article or would like to talk to us about decks, please call us at (604) 626-7100.