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Does a Hot Tub Have to Sit on Concrete? (No; You Have Options!)

Shopping for a hot tub can be fun. But before you step into a showroom, there are a lot of questions that need to be answered, such as what it’s going to sit on. If you’ve wondered does a hot tub have to sit on concrete, read on!

A hot tub does not have to sit on concrete and can be placed on any stable, level surface that will not become unstable due to moisture or weight. Those surfaces include wooden decks, paver stones, gravel beds, or spa pads.

Just don’t place a hot tub directly on the ground or on a wooden deck that was not built to support the weight of a fully-loaded hot tub. Concrete, however, remains an excellent choice for hot tubs.

Who doesn’t dream of having a hot tub in their backyard? A place to relax and soak in warm water sounds delightful!

But there are do’s and don’ts to everything, and that applies to hot tubs too! You’ll want to make sure you have a stable base that your stable base that your hot tub sits on. Keep reading to find out what bases work, and what doesn’t!

Before you decide on a base, know what your hot tub weighs!

Whatever surface you choose to put your hot tub on, it’s important to know how much weight per square inch that surface can take.

Hot tubs weigh a lot; especially when full of water and people.

But how much do they weigh and how much weight difference is there between different sizes of hot tubs? Luckily, I break it all down for you in a recent article.

Just click that link to get accurate estimates for how much yours weigh. Or how to calculate it if yours is an out-of-the-ordinary size or shape.

What is the best base for a hot tub?

The best base for a hot tub will be a concrete pad that is at least 4 inches thick. The concrete should be allowed to cure for 28 days minimally and be level. 

A proper foundation for your hot tub is key before installing it! You want to make sure you can get the most out of your hot tub without any issues, and this will ensure that.

Some of the most common surfaces hot tubs rest on are level concrete slabs or reinforced decks.

But depending on the spa model you purchase, concrete may not be necessary. In fact, a hot tub does not need to sit on concrete does not need to sit on concrete if you wish to have a different base.

But, do not place the hot tub on grass or bare earth.

Other great options to place your hot tub on includes:

  • A level pad built out of stone pavers
  • Reinforced wooden decks
  • A spa pad made out of heavy-duty plastic
  • Gravel beds 

The gravel conforms to the hot tub base and will hold it in place.

Another cheap option is a prefabricated base, usually called a spa pad. This is a system of interlocking pads that can be used to create the base. Many say it is just as good as concrete, in addition to being cheaper.

I mentioned spa pads there, which you may not have heard of.

Essentially, those take the place of pavers or concrete and are a lot cheaper! Start by using a shovel to get the ground level. Then add fine gravel or sand to even it out and place the spa pad on top.

Spa pads may be plastic, but they can take the weight!

And unlike loading up 60 or so stone pavers into your car from Lowe’s, this thing only weighs 15 pounds total for an 8’x8′ pad, delivered to your door for free from Amazon!

CLICK HERE to see my pick for a spa pad on Amazon.

As long as the surface is uniform, solid, level, and can support the weight of the hot tub (remember to include the hot tub filled with water and occupants in your calculations) then you are all set to go.

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

A concrete slab designed to support the weight of a hot tub should be 4 inches thick minimally.

A hot tub filled with water and occupants is very heavy, so you must ensure that it rests on a strong and level surface. Unsound and uneven surfaces can damage the hot tub and even invalidate your warranty!

Concrete can be a good foundation base. However, it is expensive. But it only requires a small amount of maintenance and adds value to your home.

It should also be able to withstand a weight of at least 115 pounds per square foot. This is especially important for larger hot tubs. Additionally, the concrete should be fully cured before placing your hot tub down.

How long should you let the concrete cure before putting a hot tub on it? We get into that next!

How long should concrete cure before putting a hot tub on it?

When pouring a concrete slab for a hot tub, allow it to cure for 28 days minimally before placing a hot tub on it. This allows the moisture to be kept in the concrete, and putting weight on it prematurely will weaken the finished product with stresses and cracking.

Concrete cures with a chemical reaction taking place between cement and water. This reaction is what binds sand and gravel together to make concrete.

During the process, also known as hydration, moisture must be kept in the concrete.

For the first several days, controlling the moisture content and the temperature of the newly poured concrete takes top priority.

You can increase the structural integrity of the concrete and make it more resistant to future cracking by paying attention to it in the days after it has been poured.

Known as moist curing, one of the most common methods for curing concrete is to hose it down frequently with water.

You should hose the concrete down five to ten times per day for the first week. This allows the moisture in the concrete to evaporate slowly.

Concrete that has been through this method is up to fifty percent stronger than concrete that was cured without the method.

However, spraying is not recommended for concrete poured during cold weather.

If you don’t have time to do moist curing, another option is to use a cover that can trap and slow the evaporation of the moisture in the concrete mix.

Polyethylene sheeting that’s at least 4mm thick or a concrete curing insulating blanket are excellent choices for this. Wet the concrete thoroughly, and then cover it.

But check with whoever is pouring the concrete for their expert advice.

Can a hot tub be placed on pavers?

A hot tub can be placed on paver stones. Just select pavers that are perfectly flat and have no ridges. Do not, however, place the pavers directly on the ground or grass. Dig into the ground 4-6 inches, level the ground, and use a bed of sand and/or gravel and place the pavers on top of that.

In fact, the hot tub at my last house was a used one I bought and placed on a pad of pavers I put together (seen in the above pic). There are a few different types of pavers that you can choose from. These include concrete, cobblestone, brick, flagstone, and rubber.

There are a few disclaimers you should consider when thinking about using pavers.

Pavers are a high-density material that offers more support than concrete slabs or wood.

Their low absorption rate makes concrete pavers resistant to common problems that happen with poured concrete, like efflorescence (salt deposits rising to the surface of the concrete).

Pavers also offer easy access in case there is an issue with buried electrical or plumbing lines. All you have to do is remove them and then replace them when the problem is solved.

Additionally, pavers offer flexible design possibilities. They come in many different colors, shapes, textures, and sizes.

Finally, unlike poured cement, you won’t have to wait a month with pavers! And you can drive to Lowe’s or Home Depot, load ’em into your car or truck and have your pad built in an afternoon.

Can a hot tub sit on decking?

A hot tub can be placed on a wooden deck as long as the deck is structurally supported to take the added weight of the hot tub, water, and people. A deck less than 2 feet off the ground may not need additional support, but decks more than 2 feet high will need additional support posts no more than 30 inches apart.

In fact, 2 of the 4 hot tubs I’ve owned sat on wooden decks, including the hot tub I own now.

When placing your hot tub on a surface such as a wooden deck, you should be mindful of the weight of the hot tub (especially when filled with water and occupants) and the amount of weight that the deck can hold.

How much weight can a deck hold?

I’m glad you asked that. Surface-level decks can almost always take the weight of a fully-loaded hot tub. But the higher off the ground the deck is, the more likely it is you’ll have to reinforce the deck support.

But how do you estimate that and how do you reinforce the deck posts if needed? 

Luckily I cover all of that in a recent article. I even show you deck plans that show the position of additional support posts on my deck. And I show you how to calculate (simply) how much weight your current deck can support.

Just click that link to read it on my site.

Here are some other things you should consider if putting your hot tub on a deck.

First, make sure that there is plenty of space around the hot tub so the cover can be removed. Also, ensure bathers can easily be able to get in and out of the hot tub.

Next, your deck should be properly sanded and finished. Splinters are the last thing you need when you’re trying to soak and relax!

Finally, add a privacy screen if you feel like there are too many eyes watching you.

Not sure how to go about making your hot tub area more private? I have you covered there too. In a recent article, I lay out 7 simple and cost-effective ways to add privacy to your hot tub!

Just click that link to read it on my site.

Can you put a hot tub on cinder blocks?

You can use cinder blocks for support, but you should not solely rest a hot tub on cinder blocks.

You need a flat, uniform, level surface. This surface must be able to hold your hot tub at its greatest weight- when it is filled with water and people. A dip in the surface your hot tub is on can cause the hot tub to crack.

In a way, cinder blocks are similar to pavers.

But just laying a bunch of cinder blocks on the ground, even if you leveled the ground first, would result in an uneven and unstable surface.

Uneven support for the weight can cause cracks in the hot tub’s shell or framing.

Also, because typical cinder blocks are hollow in the middle, their support would probably not be sufficient to hold the weight of a fully-loaded hot tub.

The only way I would do it would be to lay the cinder blocks out on a bed of level sand and then mortar the blocks together to make a level and uniform base. But that’s a lot of work and there are better options out there.

Lastly, they’re not very attractive.

If you spend all the money on a nice hot tub, why junk it up with cinder blocks. Pavers are just as cost-effective and will work much better.

Just make sure the pavers (or whatever surface you choose) is level.

An uneven base, as I mentioned, can cause stress fractures in the hot tub’s acrylic shell or wood frame. But it can also cause the water to lean more to one side than the other which can make your soaks less enjoyable.

To learn more about why a hot tub needs to be level and how to level yours if it’s not, check out this recent article.

I get into some easy ways to shim yours correctly to get it level that doesn’t cost an arm and a leg. Just click that link to read it on my site.

Final Thoughts

There is no exact best base for a hot tub.

All of them have their pros and cons. You can use a concrete slab, pavers, decking, heavy-duty plastic, or gravel beds. You just have to ensure that your desired base can support a hot tub full of water and occupants.

The base of the concrete slab concrete should be about 4 inches thick.

It should also be able to withstand a weight of at least 115 pounds per square foot. Additionally, concrete takes around a month to cure properly. So don’t put your hot tub on until it is done.

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Jeff Campbell