Does a Hot Tub Have to Sit on Concrete?

Deciding what hot tub base you are going to choose can be hard. Most people suggest using a concrete base. So, does a hot tub have to sit on concrete?

A hot tub doesn’t have to sit on concrete, but it’s recommended. A concrete base that is thick enough and cured can hold the weight of the hot tub without any problem. 

The concrete base also adds value to your home and looks good. But, it can cost more than other hot tub bases.

How Thick Does a Concrete Need to Be for a Hot Tub?

A concrete slab needs to be about 4 inches thick. It should be able to support about 120 pounds (54 kilograms) per square foot, and it should be wider than the bottom part of your hot tub.

Any base required for a hot tub must be level, strong, and wide enough to support the weight and size of the hot tub without any problem.

A hot tub at full capacity can weigh between 3000 pounds to over 6000 pounds depending on the model and size. If the concrete slab isn’t thick and strong enough, it will start to crack and eventually give way. That will ruin the concrete slab not to mention the damage it will also cause to the frame of the hot tub.

4-inches of concrete may seem a lot for most homeowners, but it’s necessary. If you decide to go for a hot tub concrete base, then make sure to put a slight slope at the sides to prevent water to get under your hot tub.

How Long Should Concrete Cure Before Putting a Hot Tub on It?

You should let the concrete cure 28 days before placing a hot tub on it. After the initial set of concrete, it takes 48 hours to dry enough so people can walk on the surface. After 7 days it can easily hold slight car traffic. And it takes 28 days for concrete to fully dry.

Curing is a term used in construction used to refer to the process of adding adequate moisture, temperature, and time to allow the concrete to reach its full desired properties.

In simple terms, after setting up the fresh concrete slab, you should regularly supply water to the concrete daily. You can even do it twice daily depending on how hot it is where you live.

However, if the weather is cold then you shouldn’t spray it. The cold weather won’t give the concrete enough time to cure. Another option is to place a cover on top of the concrete so it can trap moisture and slow down the evaporation.

You should never place your hot tub before the concrete has fully cured. A not fully cured concrete won’t be able to hold the hot tub weight. After a few days, the concrete will crack and damage your hot tub.

Related Read: Can a Hot Tub Sit on Gravel?

How Many Bags of Concrete Do I Need for a Hot Tub Slab?

It depends on how large your hot tub is. A smaller hot tub needs a concrete base of 270 square feet. For a 270 square feet base, you need about 180 concrete bags (80lbs). 

The number can be different because different hot tub models have different sizes. You should always measure the hot tub size beforehand, and then make the concrete base wider than the base of the hot tub. You want some space for other things near the hot tub.

It costs about $5 to 10$ for a square feet concrete base. Depending on how large the hot tub is, it may cost you $500 to $2500 for a hot tub base.

Related Read: Can You Put A Hot Tub On Grass?

What Is the Best Base for a Hot Tub?

Generally, the best base for hot tubs is a concrete slab. The concrete slab is usually set up by first digging about 2 feet or more into the ground and then filling the space with gravel before pouring the mixed concrete paste. When the mixture solidifies, you will end up with a very strong base for any hot tub.

Not only that, a concrete slab gives you the luxury of beautifying your hot tub space anyhow you want to. Any additional detail, be it artificial grass, flowers, and the likes will fit and blend perfectly on a concrete slab.

While concrete slabs are the most common base used by many hot tub owners, it isn’t the only base capable of carrying the full weight of a hot tub.

Other popular choices include hot tub pads, pavers, gravel, and reinforced decks. Overall, the best base for your hot tub depends on your decision, the qualities of the base, the hot tub model you have, and the capacity of the hot tub too.

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What Are the Alternatives to Putting a Hot Tub on Concrete?

A concrete slab is a common base for a hot tub but it isn’t the only base deemed suitable. There are different hot tub bases that a hot tub can be placed on, so it’s all about your hot tub and your choice.

1. Reinforced Wooden Deck

A hot tub can be placed on a wooden deck but you need to be sure the deck can support the weight of the hot tub at full capacity of water and bathers. A deck built at 2 feet above the ground level can support about 100 pounds per square foot of weight which is okay for many hot tubs but not all.

If you want to determine if your deck can support the full weight of your hot tub, then click the link.


  1. A reinforced wooden deck adds style and class to your hot tub space.
  2. A hot tub placed on the deck is closer to the home so you have increased comfort, security, and privacy.
  3. A reinforced deck is strong enough for even the larger 7-person hot tub.


  1. Reinforcing a wooden deck can be costly and is not usually a task you can execute yourself.
  2. A poor-quality wooden deck can be discolored and weakened by the treated water from your tub.
  3. A wooden deck will need regular cleaning and maintenance which might not be your gig if you have a tight schedule.

2. Hot Tub Pads/mats

Hot tub pads are made from a variety of materials, mostly plastic. That it’s made of plastic doesn’t mean it can’t support the weight of a hot tub. Some hot tubs even come with their hot tub pad. The pad is a ready-made base for the hot tub.

As an added advantage over the concrete slab, hot tub pads are cheaper, lighter, and you don’t have to wait for 3 weeks before you can put your hot tub on them. You do need to pay attention to the instructions on your hot tub pad though.


  1. Hot tub pads are a cheaper alternative if you need a pocket-friendly hot tub base.
  2. They are specifically built for the hot tub.
  3. Hot tub pads are ready-made.
  4. Hot tub pads are easy to install.


  • Some hot tub pads still need to be put on a strong base which means you can’t just place them on the ground.
  • Hot tub pads will need regular cleaning and maintenance.

Related Read: Can An Inflatable Hot Tub Fit Through A Door?

3. Gravel

The low cost and ease of drainage make a gravel base another common choice for hot tub owners. A gravel base is strong, cannot be damaged by water, and it makes drainage easier.

Though the method of construction is somewhat similar to making a concrete slab, you should contact a contractor to do the measurement, recommendations, and help you out if you aren’t experienced with such tasks.


  • Gravel bases are as strong as concrete.
  • They are cheaper to install.
  • They don’t need regular maintenance or cleaning. The base is mostly crushed stone which cannot be damaged, discolored, or corroded.


  • They aren’t the most stylish of hot tub bases. If you fancy home décor, I doubt this will be your pick.
  • The base can be hard on the feet.

There are other durable materials and bases capable of supporting the weight of a hot tub such as stone pavers. However, you need to consider the weight of the tub at full capacity, your budget, and available space among other factors before picking a hot tub base.

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