4 Great Hot Tub Base and Foundation Ideas

How do you choose the best hot tub base? Before we begin – we suggest making sure you check with your hot tubs warranty section to make sure the foundation you choose will put you in the best position to keep your hot tub working for many years and keep you covered in case something ever happens and you need the warranty.

Ultimately, our guidelines say “The spa must be placed on a level concrete slab sufficiently engineered to support the entire length and width of the spa when filled to capacity. Standard building practices must be followed. Damage caused by failure to have a properly leveled and supported foundation under the spa is not covered under warranty.

hot tub foundation tools - best foundations for a hot tub

Your hot tub is scheduled to arrive soon, and you couldn’t be more excited. Your fluffiest towels are ready, and you can’t wait to soak. However, you haven’t put down a base for it to sit on. 

Oh, well — it’s probably fine to put it right on your lawn, right?

Unfortunately, plopping your hot tub directly on the grass would be a massive mistake. Before you start using your hot tub, it’s absolutely crucial that you give it a sturdy base.

Here, we’ll show you four fantastic hot tub base and foundation ideas, so you can enjoy your hot tub to the fullest:




Pre-made base.

Ready to create a durable, long-lasting base for your hot tub? Just keep reading.

hot tub base grass

Why Is a Hot Tub Base Important?

Before we get started, let’s review why you should give your hot tub a base to begin with.

First and foremost, there’s your hot tub’s weight: Even if you purchase a relatively small hot tub, it will still weigh thousands of pounds.

After all, just one gallon of water weighs 8.34 pounds. In a standard 400-gallon hot tub, that comes out to 3,336 pounds of water weight, not including the hot tub itself.

Needless to say, a hot tub that weighs thousands of pounds will not sit evenly on a grass or dirt surface. Rather, it will sink significantly, ruining your yard in the process.

You also need to consider the damage your hot tub will incur if placed on a grass or dirt surface.

Even in dry climates, the lower layers of soil are moist, and over time that moisture will wreak havoc on your hot tub’s structural integrity.

Remember, even though hot tubs are designed to hold water, their exterior surfaces are not designed to withstand prolonged water exposure.

Now that you know why it’s so important to give your hot tub a base, let’s look at four of the best base and foundation ideas.

1. Concrete/Cement

You’ve probably heard of both concrete and cement hot tub bases. The truth is, cement is an ingredient of concrete, along with water and an aggregate like rock, sand or gravel. 

Although slightly more expensive than gravel alone, concrete bases are still very affordable, as well as ultra-durable and long-lasting. 

Once your concrete base is complete, you won’t have to think about it again for a long, long time. 

The process of creating a concrete base is very similar to that of a gravel base: you’ll need to start with an excavated area that’s big enough for the bottom of your hot tub, though you won’t need to dig as deep — four inches will suffice. 

Next, use 2-inch x 4-inch boards to build a frame inside the pit. 

Finally, cover the bottom of the pit with about an inch of sand, then pour the entire amount of concrete over it. Smooth out the wet concrete with a board followed by a bull float, then trowel the surface after it begins to set. 

To get a more detailed description of the process, simply perform a quick internet search — many comprehensive guides on the topic are readily available. 

Hot Tub Concrete
Hot Tub Gravel

2. Gravel

With its low cost and ability to provide constant drainage, gravel is a popular choice with many hot tub owners. 

Keep in mind, though, that you can’t simply pour a layer of gravel onto your lawn and call it a day: An effective and high-quality base will require a little more work. 

To create your gravel hot tub base, start by calculating the ground space your hot tub will take up. 

Then, mark out an area in your yard that’s big enough to accommodate that, plus a few extra inches on the sides for good measure. 

Next, dig a six-inch-deep pit in the area you’ve marked, ensuring that the bottom is as level and smooth as possible. 

Line the bottom of the pit with landscape cloth, then fill the first four inches of the pit with medium-grade gravel. 

Top with smaller gravel like pea gravel, and rake until smooth.

3. Decking

If you’re planning on placing your hot tub on a pre-existing deck, we have good news for you: your hot tub base is already built! 

However, it’s absolutely essential that you have your deck evaluated by a professional before you place your hot tub on it. 

After all, a pre-existing wooden deck might not be able to support a full hot tub weighing thousands of pounds. 

Depending on the weight capacity of your deck, it will likely need to be reinforced with additional framing, including extra joists. 

This should typically be done by a professional, although you can DIY it if you have some prior construction and reinforcement experience. 

Hot Tub Decking

4. Pre-Made Base

If the thought of reinforcing your deck, pouring gravel or mixing concrete isn’t appealing to you, you might want to consider purchasing a pre-fabricated base. 

These bases can cost anywhere from $100 to $600 depending on the vendor you choose, though most are available for about $150 to $200. 

Although a pre-made base can be more expensive than DIY gravel, concrete or deck bases, they can also save you a great deal of time and give you peace of mind. 

This is especially true if you have little or no experience with landscaping or basic construction. 

No matter which type of base you choose to go with, what’s most important is that you install a base from the get-go. With a proper base installed, your hot tub can provide reliable relaxation and fun for many years to come. And again, check your warranty for foundation info. Make sure you choose the foundation that’s best for you and keeps you in warranty!

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