Concrete Pad for Hot Tub – Thickness – How to build one?

Saad Iqbal | 🗓️Modified: August 17, 2023 | ⏳Read Time: 8 min | 👁Post Views: 144

So, after you’ve got a brand new hot tub for your outdoors; but are now looking to know about building a concrete pad for it. That’s where you need to know about things like; how big of concrete pad do I need for a hot tub or how thick does a concrete pad need to be for a hot tub?

Here’re some quick answers to your queries:

Size of concrete pad for hot tub

Standard hot tub has a size between 5’x5’ that goes up to 8’x8’; so an ideal size of concrete pad for hot tub would be 8’x8 to 10’x10. Having this extra board gives you a hard stable step so you won’t tip off. The idea is to have a size of the pad large enough that can fully support the bottom of your hot tub.

Also Read: 918 meters long concrete water bathtub in Germany

How thick does a concrete pad need to be for a hot tub?

The ideal range for thickness of the concrete pad for hot tub is 4” to 5” reinforced with appropriate number of reinforcement. The exact thickness and reinforcement requirement depends ultimately on the weight of the hot tub.

A typical hot tub when filled can have a weight of up to 6,000 pounds and so you need to have a reliable and stable foundation to support it.

But that’s not all; you know the exact requirements of thickness and size depends a lot on different factors that I’m going to reveal in our today’s article. So, I recommend you continue reading the entire article and even know how to pour a concrete slab for a hot tub.

Let’s delve straight in:

Also Read: DIY Pool Removal – 8 Reasons it’s not the best approach

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Is a concrete pad the best base for hot tub?

Yes, concrete in comparison to other options like gravel, paver stone, or wooden decking is far more stable, durable, and long lasting. Reinforced concrete pad is structurally capable of supporting the weight of a full hot tub and the people using it.

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The cover of around 18” around the hot tub would also help people get in or out of the tub. Moreover, this cover is required along each side during maintenance and repairs. Moreover, if you allow extra space around the hot tub, it will give you a margin to have a larger hot tub in future without the need to demolish and add a new slab.

Considerations for the concrete pad

Here’re some important considerations you need to keep in mind before pouring the concrete slab for hot tub:

  • Thickness: Make sure the thickness of slab is more than 4”. This is a conservative number so that the weight of the water and hot tub can be easily distributed on the soil underneath.
  • Drainage: Drainage is also a pretty important aspect. You need to have a very slight slope on the concrete but not steeper than 3/16” over a foot. A slope like 5/8” over 8’ is also ideal as it won’t let any standing water on the concrete pad.
  • Level: We need to have a flat and uniform surface for the pad to avoid crack or damage to the tub. A flat surface will not only be stable as a foundation but will also avoid any tipping hazard.

Also Read: Can We Put Swimming Pool Above Ground On Pavers?

How to pour a concrete slab for a hot tub?

Before you can pour a concrete slab for hot tub, make sure you have fixed the wooden form as per the size of the slab. For the concrete pad, you also need to have a stable ground. So, make sure to excavate like 6 inches into the ground and have a base layer of gravel followed by pouring of concrete. At the end you can screed the concrete followed by curing for around 14 days.

Also Read: 5 Tips for Maintaining Your Concrete Swimming Pool

Pouring concrete slab for hot tub:

Making sure your hot tub is safe for fun times is important. If your hot tub sits on an unstable surface, like grass, it might sink or move, which isn’t safe. A good choice is to put it on a concrete slab. These slabs are custom-made for your hot tub’s size and can hold its weight.

Here’s what you need to make a concrete slab:

  • Shovel
  • Long pieces of wood (2-by-4)
  • Wooden sticks
  • Concrete mix that’s ready to use
  • Screws (3 inches long)
  • Electric saw
  • Electric drill
  • Tape measure and level

Once you have your tools and things ready, decide where you want the slab. Ask your local building department if you need permission before you start. Choose a flat piece of land.

Now, let’s begin with the steps to pour the concrete slab for your hot tub:

  • Step 1: Mark where the slab will go. Hot tub slabs are usually smaller than 10 feet by 10 feet, but adjust based on your hot tub’s size. Dig the spot, but not deeper than 4 to 6 inches. A good, solid base is needed.
  • Step 2: Cut your pieces of wood to fit the area. Put them together like a frame, using screws at each corner. The inside of the frame should match the size of your slab.
  • Step 3: Keep the frame steady by using wooden sticks. Check if the frame is even using a level before pouring concrete. This step is super important.
  • Step 4: Put about 1 to 2 inches of gravel or sand inside the frame. Follow the instructions to mix the concrete. Pour it into the frame, making sure it gets into the corners and tapping to get rid of air bubbles.
  • Step 5: Flatten the surface of the concrete using a long piece of wood (2-by-4 inch). Move it back and forth to make the surface even.
  • Step 6: Now, the waiting part. Let the concrete dry. Wait at least two days before removing the frame and 28 days before putting your hot tub on it. This makes sure the slab is strong and ready.

Remember, safety first!

Also Read: How Much PSI to Clean Concrete? – Pressure washer

Different Materials for Hot Tub Bases

If you’re not sure if a concrete pad is the right choice for your needs and budget, there are other options you can consider. These might suit you better:


This option is affordable and simple. You just need a layer of gravel, which is easy to install and doesn’t take much time. If you want something strong and long-lasting, gravel is a good choice. Unlike concrete, it won’t crack or move with time. Plus, it’s great for draining water, so your hot tub area won’t get soggy.

Paver Stones

Pavers are a cool way to make your hot tub area look nice. They come in different shapes, sizes, and colors, so you can find the ones that match your space. Like gravel, they stay stable and won’t crack or shift over time.

Wooden Decking

Decks are popular for hot tubs because they’re stylish and give you extra space. With a deck, you can make a cozy seating spot or a place to have fun around your hot tub. But remember, this might cost more than the other choices. You’ll need an expert to make sure the deck can hold the hot tub and people safely. Sometimes, extra support might be needed, and that could raise the installation cost.

Do I need concrete pad for hot tub?

Yes, the concrete pad is required for a hot tub not just to get hold of its load in full but also to have a levelled and stable base so it won’t de-shape or damage the tub.

What kind of pad do you need for a hot tub?

You need a concrete pad of size around 1.5’ large in size than that of the hot tub on all the sides to allow for a stable base and to transfer the weight of the hot tub to the ground.

Can a concrete slab hold a hot tub?                

Yes surely a concrete slab can easily get hold of a hot portable tub. It is durable and is long lasting unlike some other options like gravel or paver stone.

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