How to Determine if a Deck can Support a Hot Tub?

If you’re currently renovating your backyard, or you’ve finally decided to treat your family (and yourself!) that hot tub you’ve had your eye on, it’s important to plan for this new addition to your outdoor space.

By itself, a hot tub is pretty heavy and, when paired with water and people, can weigh upwards of five thousand pounds! For this reason, it must be given proper support, as a hot tub placed onto weak foundations will be nothing short of a recipe for disaster.

This is where we come in! In this article, we’re going to be explaining some easy and quick calculations that you can make to determine if your decking area is strong enough to withstand a hot tub.

This isn’t something you want to get wrong, so we highly recommend double-checking your estimates with a professional. It’s better to be safe than sorry!

How much will my hot tub weigh?

The overall weight of your hot tub is going to depend on what model you buy, its size, and the materials used to make it. However, once it gets filled with water and people, your hot tub can easily weigh up to 5000+ pounds. 

As an example, if you have a six-person hot tub, the tub itself will likely weigh in the area of 900 pounds.  Let’s say you needed to add 400 gallons of water to make it full, this will bring the weight up to around 3,500-700lbs.

Then, add the weight of six fully-grown adults and you’re looking at a total weight of around 5 thousand pounds.

 Though this is just a scenario, it demonstrates how quickly the weight of a hot tub can add up, which is why it’s important to make sure your deck can support one.

To help simplify, here’s a breakdown of varying hot tub sizes, and a rough estimate of how heavy the hot tub will be:


These are just industry averages, and not all hot tubs are going to be made in the same way. When you’re selecting a hot tub, you’ll be able to find the exact weight of the hot tub by looking at the specifications. 


Additionally, if you’ve already purchased one and are unsure of the weight, refer to the owner’s manual.

Calculating Weight Bearing Requirements

As hot tubs are quite small, their total weight will be concentrated into a small portion of your deck. If you already have a deck, there’s a chance that it isn’t built to withstand a hot tub.

Rather, they are designed to hold chairs, people, and BBQ grills.

If you plan on putting your hot tub on your existing deck, you’re likely going to have to add additional support to make it strong enough to withstand the weight of your hot tub.

Standard desks that are raised 2 feet off of the ground, tend to have support beams positioned underneath, at a distance of around 6 feet per beam.

Though this isn’t strong enough to withstand a hot tub, you’ll be able to get underneath the decking and add additional beams.

However, if you’re unsure, we recommend contacting a professional, such as a general contractor, who will be able to assess the decking area for you and inform you of what steps you need to take to make your decking area suitable for a hot tub.

On the other hand, if you have decking installed in your backyard that is just over the ground, it should be able to take around 100lbs per square foot, which will be more than enough to hold small to medium-sized hot tubs, including the people and water.

This is just an industry average figure, and you should double-check your particular decking’s weight capacity per square foot by contacting the manufacturer.

If you do want to the calculations yourself, here is a simple calculation method to work out the weight capacity per square feet:

  • Write down the total weight of the spa when empty 
  • Take the number of gallons of water needed and multiply by how much a gallon weighs 
  • Add the two figures together
  • Take the number of people using the hot tub and multiply by the average weight of each person 
  • Add that number to the previous total
  • Divide that by the number of square feet, and you’ll have your amount

Placing Your Hot Tub on Your Deck

After you’ve chosen a tub and prepared your decking area, another big decision to make is where to place your hot tub!

If your decking is directly next to your home, placing your hot tub against the wall of your home will offer some privacy, as well as protecting you from the wind. Plus, the closer the hot tub is to your backdoor, the easier it will be to get indoors, especially on those chillier nights!

You’ll also want to make sure that there is enough space around the hot tub so that you can easily get in and out without any danger.

The engine area of the hot tub should be easily accessible for general maintenance, and if possible, you should be able to walk around the tub so that you can easily put its cover on and take it off.

Tips for Choosing the Right Hot Tub

  • Before making a purchase, make sure that you research the reputability of the manufacturer and read reviews from people who have already purchased the hot tub
  • If you’re apprehensive about purchasing a hot tub online, why not visit a hot tub store near you and test a few out for yourself?
  • A hot tub is an investment, so make sure that you carefully consider how much it’s going to be to maintain your hot tub, as well as whether or not you are covered by a warranty
  • If you live alone or require help with transport or installation, the store or website you purchase it from will usually deliver the hot tub straight to your door. Some even offer installation for an additional cost. However, you could contact a general contractor that will be able to do that for you if they didn’t.