How To Determine If A Deck Can Support A Hot Tub?

If you just got a hot tub, and you have a deck. You must be wondering if the deck can support the hot tub weight. After all, hot tubs weigh a lot. So, how to determine if a deck can support a hot tub?

If your deck was installed less than 2 feet from the ground level, then chances are the deck can support your hot tub. If your deck was installed higher than 2 feet from the ground level, then you would need to modify the deck.

A deck installed below 2 feet from the ground level can support about 100 pounds (45.3 kilograms) per square foot of weight You don’t need to be discouraged. My deck was installed about 4 feet from the ground and it still bears the weight of my 6-person hot tub. I just had to modify it.

Can a Hot Tub Be Placed on a Deck?

Absolutely, but it needs to be reinforced to do so. It is advised to have a professional come and check it out to verify that you can place a hot tub on it. With the proper support, your deck can bear the weight of your hot tub at full capacity of water and bathers without any stress. You just have to choose the method of installment that you want.

Before we move on, here is a quick heads up for you. Placing your hot tub on your deck is not a project you want to take on yourself. While there are parts of the project you can do, the bulk of the calculation and placement should be left to a professional.

I probably know more about hot tubs than you do and I still consulted help for mine. A poorly installed hot tub on a deck can lead to serious injuries to the bathers and damages to the house. So, get help.

Methods of Hot Tub Installment for Decks

When it comes to placing hot tubs on decks, there are two methods of installment. Both methods require a strong and leveled surface.

You can have your hot tub placed directly on the deck: For this, you would need to add support beams below your deck to support the weight of the tub if the deck isn’t strong enough. You would also need to add a few stairs to the side of your hot tub, so you can get in easily. This is a common method in most homes.
You can also have your hot tub placed inside the deck: For this, you might need to create a gap in your deck for the tub to sit in and install a concrete slab below your deck for the hot tub to sit on. If you install the tub this way, you can get in easily because the tub will be on the same level as the floor of your deck. This is perhaps not the best installment method for a home with toddlers.

Related Read: Can I Put My Hot Tub on Ground?

What Should I Consider Before Placing My Hot Tub on My Deck?

Before placing a hot tub on the deck, you should consider a few factors such as:

The weight of the tub. This is undoubtedly the most important factor to consider. For decks, you need to know the weight of your hot tub per square foot. We’ll discuss how to determine that later in this article.
The condition of the deck. You shouldn’t place a hot tub on a damaged, aged, or rotten deck. If you suspect your deck is not strong enough, consider making repairs before going ahead. Your deck should also be level and even.
The proximity to a water source. Hot tubs need water to function. Ensure you have a good source of water for times you want to fill or refill your tub. This shouldn’t be a problem since your deck is in your yard.
A constant power source. You need electricity to power your hot tub, so before picking a spot on your deck, ensure you can get a constant power supply to reach that spot without trouble.
Determine how much weight your hot tub can support. The weight of your tub per square foot will determine if the deck can hold the tub or you will need to get reinforcements.

Can I Put My Inflatable Hot Tub on My Deck?

Provided the deck is in good condition which means it has no splinters, breaks, or rots that can puncture or damage the tub eventually, yes you can.

Inflatable hot tubs at full capacity weigh about 3500 pounds. Divide that number by the square feet of the hot tub which is about 38 sq. ft., you will get 92 pounds per square foot in weight.

That is very much suitable for a deck installed 2 ft. above ground level. If the deck was installed higher than that, you might need to install a few extra beams. Regardless, you should be fine with an inflatable hot tub on a deck in good condition.

The weight of the inflatable hot tub makes it possible for them to be placed on just about any deck without serious concern.

What you need to consider is the condition of the deck. While most inflatable hot tubs are engineered to be puncture-resistant, you shouldn’t test the level of resistance by placing it on a damaged deck full of splinters and broken wood.

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

Remember when your teacher said something like, “pay attention in math class, you will need the knowledge in the future”? Well, your teacher wasn’t lying.

To know how much weight your deck can support, you will need to do a bit of calculation. There are different ways to go about this, but let’s consider an easy one.

To calculate how much weight your deck can support, you need the following in numbers:

The weight of your hot tub on its own. This varies based on the size and model of the hot tub you have.
How much water (in gallons) your hot tub can take.
The weight of the water. A gallon of water weighs 8.34 pounds (3.78 kilograms).
The average weight of a bather is 175 pounds (79 kilograms).
The square feet of the hot tub. This varies according to the size and model of the hot tub you have.

For this explanation, we’ll be using the figures of a 6-person hot tub.

Note that even with this, there are still different models of a 6-person hot tub out there. The figures below are mere representations of just one type of the 6-person hot tub. The figures of your 6-person hot tub or any other hot tub you have could be different. You can just substitute the figures below for yours.

For the weight, most 6-person hot tubs weigh about 850 pounds (385.5 kilograms) while empty.
For the amount of water, most 6-person hot tubs can hold 420 gallons (1589 liters) of water. Many can hold even more. Given that a gallon of water weighs 8.34 pounds (3.78 kilograms), that means 8.34 (the weight of a gallon of water) x 420 (the number of gallons a 6-person hot tub can take) = 3502 pounds (1588 kilograms).
For the weight of the bathers, a 6-person hot tub can accommodate 6 people at once. Given that the weight of an average bather is 185 pounds (84 kilograms), that means 185 (the average weight of a bather) x 6 (the capacity of a 6-person hot tub) = 1110 pounds (503 kilograms).
For the square feet of the hot tub, most 6-person hot tubs are 56 square feet.

How Do I Make My Deck Strong Enough for a Hot Tub?

There is a golden statement with decks and hot tubs. “The higher the deck is from the ground, the lower the weight it can support” In other words, a lower deck can support heavier weight than a higher deck.

If your deck is higher than 2 feet from the ground, then you should consider modifying the deck. So, how do you go about modifying your deck to hold a hot tub?

There are usually two ways to modify a deck when it comes to hot tub installation. Both methods depend largely on the method of installation you want.

Install Extra Support Beams

If you aim to place your hot tub directly on the floor of your deck, then your installer will advise you to Install extra support beams so the deck can support the weight of the tub.

For this method, thick wooden posts or beams are installed about 30 inches apart from one another. The number of posts required will depend on the posts previously installed, the size of the tub, and the weight of the hot tub.

Usually, about 7-9 extra posts should be enough. The posts will go into the ground and be placed underneath the area of your deck where you want to place the tub.

Install a Concrete Slab Below

If you aim to place your hot tub inside the deck, then you would need to install a concrete slab below your deck.

This method is common among people that have decks that are already high, usually 4 feet and above. The height of the deck from the ground makes it possible for your installer to go underneath the deck easily.

For this method, you might be required to create a space in your deck for the hot tub to sit. This means saying goodbye to a part of that fancy woodwork. Not to worry, something even fancier is coming in its place.

When space is created, the ground is dug and then filled with crushed stone, gravel, and sand to serve as the foundation. Then a concrete slab is installed on it.

The concrete slab is what your hot tub will sit on. The slab is usually 4-6 inches thick and that is more than enough strength to support your hot tub.

After the hot tub is set in place, the spaces between the hot tub and the deck will be covered with hardwood to make the space look even and neat. The bonus point of this method is that your deck is doing nothing. The concrete slab is doing all the work while the deck just houses the hot tub.

Can a Trex Deck Hold a Hot Tub?

The term “Trex” sounds like those tough German or Russian names you hear in movies. Like “Victor”, “Vladimir” or “Rusev”. That’s just me joking around, let’s get serious.

A well-installed Trex deck can support the weight of a hot tub provided it is strong enough. Trex is also called “composite decking.” The Trex deck is not stronger than normal lumber or wood, but it is more resistant and durable. A Trex deck will not rot, will not splinter, and will not crack for a long time. Trex is usually advised for outdoor wooden structures like decks because of its high resistance to harsh conditions.

In terms of strength, a Trex deck matches the normal wooden deck so don’t misinterpret durability for strength. If you want to install your hot tub on a Trex deck, you can but you should take into consideration what we discussed above.

Check the height of the Trex deck from the ground. If it’s more than 2 feet, you should modify the deck.
Calculate the weight per square foot of your hot tub at full capacity. If it is more than 95 pounds per sq. foot, then you should modify the deck by using a concrete slab or wooden beams.

As long as the Trex deck is strong enough, it can support the weight of a hot tub.

There you have it. If there is anything else about hot tubs you aren’t sure about, you can let me know below in the comment section and I’ll answer your questions as soon as possible. Have a nice day.