how to determine if a deck can support a hot tub

If you’ve been dreaming of adding a hot tub to your deck, wait! The first thing that you need to do is determine whether or not your deck can actually handle a major piece of equipment like a hot tub.

When doing any serious projects like this, it is important to be cautious. Adding a hot tub to a deck without any preparation can be dangerous. The last thing you’d like to deal with is a deck collapsing due to the weight of a 1,000lb spa.

Luckily, we can provide you with a few tips for careful planning so that you can build the backyard of your dreams.

Continue reading to find out more!

What Kind Of Hot Tub Should I Install On My Deck?

When it comes to deciding what type of hot tub you want to install on your deck, you have two main choices:

  • A hot tub that is set into the deck (in-ground hot tub)
  • A hot tub that sits on top of the deck (above-ground hot tub)

In-ground hot tubs are very popular choices for those who have decks, as these hot tubs don’t get in the way of the view or act as much as an obstruction as an above-ground model. Plus, in-ground hot tubs are much easier to get into, which can be great for senior citizens or for those with physical limitations.

However, above-ground hot tubs are much easier to install, as you simply place these hot tubs atop your deck. Of course, you will need to consider the capacity of your deck before placing these kinds of hot tubs on your decking.

Click below to check out pricing of in-ground hot tubs:

In-Ground Hot Tub Costs

Installation Requirements for Hot Tub Deck Installation

Regardless of what kind of deck you have, you’ll need it to be a flat surface to install your hot tub. This is why most hot tub users resort to concrete slabs. Most of the time, these concrete slabs are four inches thick at the least. If you have an existing deck, you need to make sure that it can handle the weight of your hot tub like a concrete slab would be able to.

How To Calculate Deck Load Capacity

It is imperative to make sure that your deck can handle the weight of your hot tub, which is why some calculations will need to be made to ensure it is sound.

Here are the numbers to keep in mind when calculating whether or not your deck can handle your hot tub:

  • Weight of the hot tub when empty
  • Square feet of the hot tub
  • The weight of one gallon of water (8.34 lbs)

  • Average human weight (180 lbs)

You’ll also need to determine how many gallons of water in a hot tub.

To calculate whether or not you can put a hot tub on your deck, use this formula below:

Hot tub weight + (gallons of water x 8.34) + (seating capacity x 180) / # of square feet = pounds per square foot.

On average, a wood deck should be able to handle at least 100 pounds per square foot. If you do your calculations and your hot tub comes in under that particular weight, then you should be able to put your hot tub on deck. Most spa models come under 100 pounds per square foot, so you should be okay. However, take caution, especially if you have a five-person hot tub or greater.

The last thing you want to do is guess, however, which is why we recommend consulting with a professional before you try anything.

Remember, your spa will be much heavier when it is filled with hundreds of gallons of water.

How To Place Your Hot Tub On A Deck

One of the major things to consider is how and where you will place your hot tub on the deck. Trust us when we say this, trying to move your hot tub around later down the line will be a major pain.

The following considerations are meant to help you get your hot tub placed correctly the first time around.

Distance From Home

Placing your hot tub against a wall is one of the best hot tub privacy ideas. This is also the optimal solution for wind blockage. If you live in an area with cold weather, especially at nights, then you can stay much warmer.

If you live in the snow, you might want to consider how close your unit is to the door so that you can run inside once your get out.

You may also want to consider placing your spa in an area that is safe to access. If it is far away from your home, slip-resistant mats can help.


When you’re relaxing in your hot tub, the last thing you want is your neighbors peeping over at you. You might also consider adding some sort of covering, such as foliage or fencing to give yourself some additional privacy. Of course, you will also need to add the weight of these items to your deck support calculations to see whether or not your deck is able to handle the additional features.

Hot Tub

When picking a spa that your deck can handle, you need to be cautious when making your decision. We highly recommend that you pick out your hot tub prior to making any structural or support changes to your deck. When trying to find the right spa for your deck needs, there are many things to consider:

  • The weight of a hot tub (the average weight of a hot tub completely full is 3,000 lbs while the average weight of a hot tub empty is about 500 lbs)
  • The gallons of water in your spa (1 gallon of water is equal to 8.34 pounds)

You also need to make sure that you can get your hot tub onto your deck. The last thing you want is to purchase a hot tub that is too large to maneuver up and on top of your deck. Make sure to perform the correct measurements after you weigh your hot tub so that you can see whether or not you’ll be able to move it up to your deck. If not, going with a traditional concrete pad might be a better idea.

Final Thoughts – Installing Your Hot Tub Model On Your Deck

So, can you put a hot tub on a deck?

Yes, a hot tub model is a serious investment. If you don’t ensure the structural integrity of your deck when your filled hot tub is on it, then you risk putting yourself, your family, and your friends in danger, not to mention wasting potentially thousands of dollars on damage repair.

Finding the right space for your spa doesn’t have to be a challenge. Simply follow the steps above to see if your decking is able to support your spa in the location you want to put it in. If you don’t already have a deck built in your backyard and you want some inspiration for your build, all it takes is a quick Google search to find thousands of high-quality decks with hot tubs.


I’ve owned 4 hot tubs, but until our current one, they’ve always been on a stone or concrete pad. Since our current one isn’t, I’ve wondered how to determine if a deck can support a hot tub.

Here’s what I’ve discovered:

Yes, you can put a hot tub on a deck. Decks built ground level up to 2 feet off the ground can support up to 100 lbs per square foot; sufficient for most hot tubs. But decks 2 feet or higher will need added support. The added support posts should be no more than 30″ apart & ideally placed in poured concrete.

But there’s a lot more to know about hot tubs and decks. After all, hot tubs, full of water, and people can easily weigh over 5,000 lbs.

So in this article, we’re exploring how to safely put a hot tub on an existing deck.

But we’ll also get into calculating how much weight your deck can support, where to add additional supports to an existing deck. And we’ll even get into what you need to consider if you’re building a deck for a hot tub.

Let’s get going!

Ready to Spend Less Time On Maintenance and More Time Enjoying Your Hot Tub?

Let’s face it. Balancing the water, cleaning filters, dealing with rashes, and trying to figure out which chemicals to buy and add can make you feel more like a chemist than someone who just wants to relax after a long hard day!

That’s exactly why The Hot Tub Handbook and Video Course is so valuable!

This is from Matt over at Swim University and he developed it for people looking to save money, time, and frustration. His tips on chemicals can save you $100/year just by making sure you buy only what you need.

So if you’re ready to stop being confused or frustrated with your hot tub and start spending more time in it, check out The Hot Tub Handbook and Video Course.

Just click that link to learn more on their website.

Check out our mountain hot tub! You can sit, relax and watch the gorgeous scenery from our My Mountain Cabin deck! Book your stay with us today! #vacationrental #cabinrental #hottub

— My Mountain Rendezview (@MRendezview) August 21, 2020

How much does a hot tub weigh?

Before we answer this, let’s look at the different kinds of hot tubs, since each will be different. Let’s also assume we’re NOT talking about in-ground hot tubs.

We have:

  • Small 2-3 person hot tubs
  • Medium 4-5 person hot tubs
  • Large 6-8 person hot tubs
  • Inflatable hot tubs

But the average hot tub weight, empty, is about 500 lbs. Of course, it’s always a good idea to check with your manufacturer about your specific model.

Here’s a handy chart showing an estimate of each of those and how much they weigh (roughly) empty, full, and at capacity with occupants:

Type of Hot Tub Empty  Water Only People & Water 
Small 2-3 person hot tubs 600 lbs 2,575 lbs 3,000 lbs
Medium 4-5 person hot tubs 750 lbs 3,700 lbs 4,420 lbs
Large 6-8 person hot tubs 800 lbs 4,300 lbs 5,500 lbs
Inflatable hot tubs (2-3 people) n/a 2,200 lbs 2,700 lbs
Inflatable hot tubs (4-6 people) n/a 2,700 lbs 3,700 lbs

These solid deck boards are great for areas of high footfall or weight, such as under a hot tub or any commercial application.

— Rinato Decking Boards (@rinatodecking) February 20, 2020

Can a deck support a hot tub?

As you can see from the above chart, a hot tub full of water and people weighs a lot!

Given how relatively small most hot tubs are, that’s a lot of weight concentrated into a fairly small area on your deck.

So just know that a normal deck raised 2 or more feet off the ground, which might have support posts every 6 feet, won’t be enough to hold the weight of a hot tub.

The good news is that if your deck is high enough off the ground to get under, it’s fairly easy to add support beams and posts to take the weight of your hot tub.

The other good news is that if your deck is just above ground level, you aren’t likely to need additional support.

When in doubt, I would have a general contractor inspect your deck and tell you if it will require additional support.

That being said, if you have a deck that’s just over the ground, it can take about 100 lbs per square foot.

That IS enough to hold most small to medium-sized hot tubs with water and people. But fear not, we’re getting into the exact calculations below.

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How much weight can my deck support?

The higher your deck is off the ground, however, the less weight per square foot it can take.

Let’s break it down, using the large 6-8 person hot tub in my chart above as an example.

  • Weight of the spa (empty) = 800 lbs
  • # of gallons of water (525) x 8.34 lbs (how much a gallon weighs) = 4,378.50
  • Add those 2 numbers = 5,178.50
  • # people (8) x 175 (average weight of user) = 1,400 lbs
  • Add that number to the previous total = 6,578.50
  • Divide that by the number of square feet (64) = 102.79

So as you can see, the largest hot tub is just a hair over 100 lbs per square foot, and that’s if 8 people are in it. For many of us, we won’t have 8 people in our tubs at one time, and we might also have a smaller hot tub.

Need an easy way to calculate square footage? Check out this handy calculator from Calculator Soup.

So if that’s you, and, as I said above, if your deck is ground level or under 2′ off the ground, you should be just fine with no additional support.

Of course, that’s assuming your deck was well-built in the first place AND is still in great shape.

We got the lights on the deck! Hot tub arrives Monday morning!

— Scott Dellinger (@scottdellinger) May 15, 2021

How can I modify my deck to hold a hot tub?

Wondering how to reinforce a deck for a hot tub?

For decks that are high off the ground and/or need additional support, here is a diagram showing you how my deck and hot tub are arranged with the additional support posts that were added under the hot tub area.

Bear in mind, this is what was done at my house (by the previous owners). You should consult a general contractor and check with your city planning office for guidance and permit info.

The added support posts are 30″ apart from one another. Posts ideally would be placed in poured concrete and run at least 1 foot below the frost line.

Of course, if you are modifying an existing deck, take great care to ensure that all footings, joists, and decking are perfectly sound and that no evidence of rot is present.

Spend a four day weekend on the deck and in the hot tub. Challenge accepted.

— Ethan Rogers (@ERogers1991) April 8, 2021

Can a Trex deck hold a hot tub?

Yes, is the short answer.

Trex is simply a brand name for what’s called composite decking. That’s a fancy way of basically saying fake wood or plastic decking.

Now, I’m not knocking it, but since most of us don’t speak contractor-ease, I wanted to be clear about what Trex is as most of us have seen it.

Composite decking is roughly 20% more expensive than traditional pressure-treated lumber, so it doesn’t fit into every budget.

Now Trex isn’t stronger than traditional wood, so to calculate whether or not you need additional support under your deck to hold the weight of a hot tub, follow my calculations above.

The advantage of Trex comes from the fact that it, like all brands of composite decking, won’t splinter, crack, or rot. Further, it also is highly resistant to mold, mildew, and moisture in general.

While a traditional wood deck might last up to 15 years, Trex and most brands of composite wood will likely last 25 years or more and most come with a 25-year warranty.

Came home to a hot tub on the back deck. O

— avery wambles (@AveryWambles) April 18, 2014

Can I put an inflatable hot tub on my deck?

Yes, is the short answer.

Because inflatable hot tubs weigh almost nothing when empty, they are quite a bit lighter than a permanent hot tub.

Using the example in my chart towards the top, we see that even a large inflatable hot tub will likely be about 2,000 lbs lighter when full of water and people than the equivalent regular hot tub.

If we apply the formula I mentioned above for a large inflatable hot tub, we have:

  • Weight of the spa (empty) = virtually nothing
  • # of gallons of water (290) x 8.34 lbs (how much a gallon weighs) = 2,418.60
  • Add those 2 numbers = 2,418.60
  • # people (6) x 175 = 1,050
  • Add that number to the previous total = 3,468.60
  • Divide that by the number of square feet (38.37) = 90.40

So, again, for decks that are basically ground level, most likely you’ll be just fine with no added support for a large inflatable hot tub.

For a deck that is 2 or more feet above the ground, even though it’s not nearly as heavy as a full-sized, non-inflatable, I would still recommend adding the extra support; who knows? You might eventually want to add a full-sized hot tub later on!

Did I cover everything you wanted to know about whether your deck can support a hot tub?

In this article, we took a look at hot tubs sitting on decks.

We explored not only whether that’s a good idea or not, but also how to figure out how much a hot tub weighs (when full). But we also looked at how to figure out how much weight your deck can take.

Ultimately, we answered how to determine if a deck can support a hot tub.

Is your deck on (or going to be) on a deck?

While your deck may only last 15 years, many wonder just how many years a hot tub will last. In a recent article, I break down exactly what the expected lifespan is of in-ground, above-ground, and even inflatable hot tubs.

I even let you know some key tips on maximizing that lifespan too, including the one thing sure to shorten your lifespan by years.

Just click the link to read it now on my site.

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