How big of Concrete Pad do I need for a Hot Tub?

You’ve decided to purchase a hot tub and create a relaxing space for yourself. But before you can bring it home, you need to prepare a pad for it to sit on. The question is, how big does that pad for your hot tub need to be?

An 8′ x 8′ to 10′ x 10′ foot concrete pad is ideal for most hot tubs as standard hot tub sizes vary between 5′ x 5′ and up to 8′ x 8′. It is nice to have extra concrete to step off onto instead of your yard. Always make sure the pad is large enough to fully support the bottom of your hot tub.

How much space do you need around the hot tub?

Hot tubs require a minimum of 18″ around each side for maintenance and repairs. 18″ is enough space for hot tub covers and for people to get in and out. This floor of this space does not need to be concrete, but it does look nicer and be easier to maintain if it is. If your hot tub is 8′ x 8′, you’ll want to increase the size of your concrete pad to provide the maintenance width desired. If your hot tub is 5′ x 5′, you may still want to consider a pad that’s 8′ x 8′ in case you want a larger hot tub in the future. 

Is a concrete pad the best base for a hot tub?

Concrete is durable, long lasting, and often the best option for a hot tub pad. 

Disadvantages of using concrete

  1. Concrete is permanent meaning you can’t move your pad later. 

If you want the flexibility of changing your hot tub location in the future, consider an alternative. You can use gravel, pavers, or prefabricated spa pads. However, most hot tub manufacturers recommend concrete. 

  1. Concrete cracks.

Some cracking can be prevented by slowing down the time it takes for the concrete to dry and sloping the surface of the pad to prevent standing water, but concrete will likely crack eventually. 

Never place your hot tub on the dirt or grass. Not only do these locations not provide the sturdy foundation needed for a hot tub, but it can expose your hot tub to insects and unwanted moisture which will ruin your hot tub in the long run.

Can I put my hot tub on my deck?

Close-up of wooden hot tub. Luxury house exterior. Blue sky background. Northwest, USA

A hot tub, empty, weighs about 500 lbs. A cubic foot of water weighs over 60 pounds. This means a 4 to 6 person hot tub full of water can weigh over 2 tons. A larger hot tub can weigh up to 3 or 4 tons. Plus, the weight of the people using it.

Most newer decks that are 2 ft tall or less are built to accommodate this kind of load, but it is a good idea to have your deck Inspected to ensure it can carry this weight. You may need to beef up your deck with added support before placing your hot tub. If you’re unsure whether your deck can handle a hot tub, contact a general contractor to have them come inspect it. 

If you’re not going to put it on a deck, a concrete pad is a great option.

Building your Concrete pad for your Hot Tub

Now that you’ve decided to pursue a pad made of concrete, and you know the size and location for your new hot tub, it’s time to think about actually building the pad. Here’s what you need to know.

Hire a contractor to pour the concrete

You will want to hire a contractor to come pour the concrete pad for you unless you have experience placing concrete.  A professional can make sure your slab is thick enough, level, and accommodates drainage to reduce standing water. 

How thick should the concrete slab be for a hot tub?

The concrete pad needs to be thick enough to accommodate this heavy weight. A 4″ thick slab of reinforced concrete is strong enough, but you can go 5″ too if you want to be even more conservative. Foundational footings are not needed for your concrete pad.

Build the pad level

Hot tub frames are built to distribute the 3 tons of water and people weight evenly through the hottub frame. If it sits on an unlevel surface, over time, the hot tub will crack and break. A flat surface is needed for the longevity of your hot tub.

How can a hot tub pad be sloped for drainage?

The max slope of the hot tub pad is about 3/16″ over a foot. Having a very slight slope on your concrete pad will allow water to drain. Do not go steeper than this slope. A 5/8″ slope over 8′ is plenty steep enough to prevent standing water on your concrete pad.


Concrete is a great choice for your hottub pad. Make sure it is at least as big as your hottub and for accessibility, oversize your pad by 18″ on each side. Ensure the concrete is thick enough, level, and drains.


Can I put my hot tub on grass?

No, it is not advisable to place a hot tub on the grass. This is not a suitable stable location and can let insects and bugs get into your internals.

Is concrete a good option for my hot tub pad?

Yes, concrete is durable and long lasting and an ideal base for a hot tub.

Can I put my hot tub on my deck?

Yes but you need to ensure it is structurally capable of supporting the weight of a full hottub and the people using it.

What size base do I need for a hot tub?

Make the concrete base as big as the hot tub and at least 4″ thick or thicker. 5 or 6 inches is even more conservative and a good thickness. There is no need to exceed 6 inches.

Do you need a concrete pad for a hot tub?

No, but concrete is a good option. You can also use gravel, prefabricated pads, decking material, or pavers. Just make sure it is level and provides the stability needed for the hottub.