Can My Deck Support a Hot Tub?

Can My Deck Support a Hot Tub?

Unless your deck was specifically built to support a hot tub, probably not.

How do you know for sure whether your deck was built to support a hot tub?

The only way to be sure is if you are the original home owner, and you made it a requirement when the deck frame was built. Even so, you’ll need to be certain that the location you planned to place the hot tub then is the same spot you want it now.

If you bought the house with a deck already in place, unless you have a hot tub on it already, it’s safest to assume that it was not built to support a hot tub.

You can always remodel your deck to be able to support a hot tub. In doing so, we always recommend consulting a structural engineer to confirm that your deck will be able to handle the combined weight of:

• The hot tub itself;
• The weight of the water filling it;
• The weight of the people enjoying it.

Let’s look at a typical example. You just purchased an average size hot tub -- typically 7’x7’ -- and you want to put it on your 49 square foot (sq ft) deck. If your deck was designed to meet current codes, it would have been built to withstand a 40 lbs per square foot (psf) live load.

Stop and think about how much 40 lbs weighs. What I handed you a 12” by 12” tile that weighed what your deck can support -- 40 lbd psf live load? You could hold that, but it’s pretty heavy and you wouldn’t want to hold it for long.

Now multiply that 40 lbs psf live load by 49 sq ft of deck and you get a total of 1,960 lbs -- that’s what the average deck built to code can theoretically support.

A 7’x7’ hot tub can be somewhere in the range of 1,000 lbs empty. With the calculations we just did, your deck might be able to support that. The weight would be concentrated in a single location, though, putting much more stress on that section of the deck frame.

Now fill your hot tub with water and people. The weight of that hot tub just ballooned to 6,000 lbs.

So now you have this tub that weighs 6,000 lbs sitting on your 49 sq ft deck designed to support about 2,000 lbs. You’ve increased your load to more like 125 psf -- three times what your deck should be able to support -- and it’s all concentrated on one section of your deck frame.

That’s like asking your body to hold not just the 40 lb tile we talked about before, but a 125 lb tile. Only weightlifters who work out specifically to increase their ability to lift heavy weights would be able to lift and hold it for long.

Your deck needs to be not just a temporary weight lifter, but a day-in, day-out weight holder.

Think about what happens if your deck isn’t designed to support that full hot tub. It will be filled with at least water, if not people, 24 hours a day, 7 days a week. Every day, that weight can potentially weaken the frame of your standard-code deck. You’re risking heavy property damage, and people could be seriously injured.

Putting a hot tub on your deck increases its load significantly -- way more than your standard deck is designed to handle. That’s why I always recommend consulting a structural engineer before placing a hot tub on your deck.