What is a good foundation under your hot tub?

So you are now prepared to install your portable hot tub. You understand the benefits of having a tub in the house, you have done your research and have found the right choice that you deem perfect for you.

Now you should abide by the following 3 rules of thumb:

  • Your tub must not be close to any power line. Never place your hot tub near an electric outlet
  • The foundation under the hot tub must be very strong
  • The foundation has to be level

Now these are the 3 most commonly used foundation types for a hot tub

1. Grass


The grass is definitely one of the most used surfaces under a blow-up hot tub. And why not? If not contaminated with broken glass or wooden sticks, it makes an awesome cushioning material.

However, the ordinary ground is not such a good insulator. Try to use a ground cloth or an air mat under the hot tub, both for heat insulation and puncture protection.

2. Concrete pad

concrete pad

This type of foundation is recommended whether or not your tub is an outdoor one or an indoor one. Your concrete pad must have the following characteristics;

  • It must be level. This is to avoid any kind of settling after you install your tub.
  • The thickness of your concrete pad must adequate to support the weight of the hot tub. While the hot tubs can be heavy, the weight is evenly spread out by the water. 
  • The size of the pad should be atleast the size of the tub.

While the following two characteristics have nothing to do with the construction of the foundation, they are equally important:

  • You should have constructed your concrete and ensure that the concrete would have dried before the delivery of your tub. This is important because you can immediately install your tub and start making use of it right away.
  • If you find any or all of the construction characteristics stated above to be intimidating, you can call on any home improvement service provider in your neighborhood.

3. Crushed gravel or stone

crushed gravel

This type of foundation is recommended especially if your tub is to be situated outside.

This foundation must have the following characteristics;

  • It must have a minimum thickness of 4 inches
  • You must construct a frame around it to keep the foundation perfectly in place
  • it must have a proper channel for drainage so that your tub would be durable

The following recommendation has nothing to do with the foundation but it is also important;

  • Try to install low-level showers around the tub. This is to ensure that you can wash your feet before entering the tub which will prevent dirt in the tub.

4. Ready-made synthetic tub pads

hot tub pads

Check out these pads on Amazon.com

These are recommended for either outdoor or indoor tubs. They have the following advantages over the other types of foundations;

  • There is no need to pour concrete or work out any other thing like that.
  • They are lightweight and less expensive
  • They are quick and easy to set up
  • They require little to no maintenance

Their pieces interlock. This means that…

  • You can easily dismantle the pad if the need arises. For example, in case you want to move out of your present location to another one.

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  1. Where can I find that wood type interlocking pieces mat for under my hot tub???????

    • Hey! Here’s something like that: https://amzn.to/2POXv72
      Just search for interlocking wooden tiles, you’ll find plenty 😉

  2. Can I put my inflatable hot tub on a small deck that sits on the ground?

    • Absolutely! Just make sure it’s sturdy enough to carry the weight of the filled hot tub.

  3. Hi can I use concrete paving slabs for inflatable lazy spa ? These are 5cms thick but I’m reading I should have a base which is 4 inches ? Thanks

    • Hi Pauline! Sorry for the misinformation, we’ve fixed it. The 5cm pads will do just fine. While the hot tub can be heavy, the weight is evenly spread out by the water.

  4. Got 20mil gravel 6 inch thick can I put a hot tub on top of this for a base .please

    • Hey! Not sure what hot tub exactly are we talking about, but if it’s an inflatable one, I would definitely use some kind of mat between the gravel and the hot tub

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