The full hot tub with bathers can weigh up to 5000 lbs. (~2 tons). Choosing a durable and solid base is a must to prevent it from cracking.
While selecting a hot tub foundation, you might get confused with so many options such as concrete, gravel, pavers, deck, or spa pad. To make your decision easier, we will cover pros and cons of each spa base and provide installation tips.
A good hot tub base should be solid and durable. Below we prepare a short comparison table between the most popular types of foundations.
Concrete | Pavers | Gravel | Wooden deck | Prefabricated pads | |
Price | High | Medium | Low | Very high | Medium |
Efforts for setting up | Medium | Slightly high | Medium | High | Low |
Appearance | Average | Good-looking | Average | Luxurious | Average |
Time-consumption | High | Medium | Low | High | Low |
Go to the detailed review | Go to the detailed review | Go to the detailed review | Go to the detailed review | Go to the detailed review |
There are TWO aspects you should understand and remember while thinking of the hot tub base.
You should know it because the bearing capacity of different materials varies. You need to be sure that the base can handle the pressure of a full jacuzzi with bathers.
The calculations are straightforward. You should know:
Here is the formula:
(Wempty + Vw8.34 lbs + Wperson N)
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Shot tub
2. Foundation should be leveled
This is a golden rule. In case the foundation is not leveled you will get many issues.
You should use a 3-4’ level to check the evenness of the foundation.
An accurate and easy-to-read 4’ level
As a rule, the minimum thickness of the concrete should be 4-6” (10.16 cm) to support the weight of the full hot tub. You can also add some reinforcement to the slab, however, in most cases, it is not necessary.
The most vital thing about a concrete slap is that it should be leveled. For this reason, many concrete patios are not suitable for setting up hot tubs. They were built a little pitched for better drainage.
📌Pro Tip! After pouring concrete, you should keep it moisturized for the first several days to ensure a proper cure. You can do it in two ways:
- Triple layers construction for maximum heat and moisture retain - Rust-resistant aluminum grommets for anchoring and staking |
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The sad truth about concrete slabs is that they are not very attractive and barely suit every exterior.
You can improve the look of your slab with deck tiles. You can use it both around the hot tub and put it underneath. One more advantage is that it gives a better feeling to your bare feet while standing on them.
Deck tiles have a different texture and look. Here are our top picks that will make your slab look better. They are also strong enough to support the weight of the hot tub.
– Easy to set up and sturdy – Water-proof and UV-resistant – Easy to clean – Can be cut with oscillating blade – To cover 8’*8′ area: 3 packs of 20 tiles | – Slip-resistant – Can be cut with a saw – Good looking – Water-resistant – Can deform under the direct sunlight |
Gravel base is a strong and easy-to-set-up material to support your spa. Actually, it proposes advantages that non-other foundation has.
There are several rules to follow while making a gravel hot tub base:
📌 Pro tip #1! You can understand that the gravel is compact enough when you can walk on the base without leaving a footprint.
📌 Pro tip #2! You shouldn’t use only pea gravel as a base. It is not strong enough to support the hot tub. Put medium-grade gravel under and then add some pea gravel above.
Pavers are another popular hot tub foundation. It is sturdy and looks fantastic.
To lay down a paver, you will need to use either sand and gravel or a concrete slab as a base.
As the first option is more cost-effective. Here are some points to make it right.
Bury in mind, that selected pavers should create an ideal flat and leveled surface to install the hot tub securely.
📌 Pro tip #1! The common material for the pavers is concrete, cobblestone, brick, flagstone, and rubber. All of them have features you might need to know while selecting.
📌 Pro tip #2! The ideal thickness of the pavers to support a hot tub is around 2-3” (5 cm).
The world-strongest gravel grids made the gravel construction even more solid. Truegrid Pro-Lite Pavers are designed for hard-duty use and can easily handle the hot tub weight even with 8 bathers.
It is made from recycled plastic, so it is a nice option if you care about the ecology. To cover 8’*8’ (64 square feet), you need to get one pack of the Truegrid Pro-Lite Pavers.
For installing the Truegrid, you should firstly put 3-4” of cracked stones and level it. Then put the interconnected grids onto it.
After that, you can put the hot tub just on the bare grid. However, most users prefer to fill it with pea gravel to make it look and feel better.
The main rule about placing the spa on the deck is that it should support more than 100 lb per square foot. The bearing capacity depends on the material, joist spacing, joist overhang, soil type, and other factors.
It is a lot of math and calculations. However, there is a simple rule for a rough evaluation:
📌 Pro tip! If the new deck is not higher than 2 feet above the ground, in most cases it can handle the hot tub weight and doesn’t require reinforcing. If it is higher than 2 feet, it will need additional support. Usually, posts should be no more than 30 inches apart.
Reinforcing the deck is not a DIY project, especially for beginners in construction and building. You should at least consult or hire a professional to make sure you will get what you want.
Additionally, if you want to place the hot tub on the existing wood deck foundation, you should check the followings:
➡️ Condition of the existing deck. Is it old, broken, has splintered, or shows signs of rotting?
➡️ Level. The surface should be flat with no imbalance. Check it at the 3-4 feet level.
➡️ Location that will ensure free access to the motor for service.
All previously reviewed options require some manual work or have waiting time or risks with getting an uneven surface. If you don’t want anything of this, the prefabricated hot tub foundation is for you.
It is made from hard plastic and can easily support the weight of the filled hot tub.
Our top pick from Amazon among hot tub bases is a Confer Handi Spa Pad.
The most affordable spa pad
Easy-to-assemble
Durable
1 pack of 6 pieces covers 8’*8’ space
Non-slip
There are two things to note about the Confer Handi Spa Pad.
Lifehack! You can use drywall screws to secure stable connections.
Inflatable hot tubs weigh less than hard-surfaced ones. They also have no frame, so the requirements of a perfectly even foundation are not so strict.
However, if the base isn’t level, it will cause discomfort for bathers as the water level will be higher on one side. Moreover, the concentrated pressure on one side decreases the hot tub lifespan.
One more factor to consider is that many owners of inflatable hot tubs tend to buy a solid option over time. Preparing a good base will save you many nerves and time in the future.
The perfect base for the inflatable hot tun is solid, and smooth, with no pecky and sharp edges. The latter can damage the vinyl. Below you can find the list of suitable bases:
In contrast with solid-frame hot tubs, inflatable ones can be placed on the ground. However, you should consider this option only for a short-term stay.
If you want to set up the tub for longer than a month, it is better to select more solid construction.
The ground is rarely even and not strong enough to support the hot tub. After some time you will end up with an uneven surface. It will shorten the lifespan of the hot tub. Moreover, the hot tub will damage the grass.
❗ Grass is a bad insulator, so you will lose a lot of heat from the bottom.
Whatever base you select, you need to place it on the protective and insulating layer. Usually, it is made of synthetic foamy material. On the market, you can find both a specifically designed mat for a hot tub and some good and cost-effective alternatives.
If you are looking for a pad that perfectly matches the footprint of the round hot tub then the CosySpa Hot Tub Flooring Protector is your favorite. It is suitable for placing a hot tub with a diameter of up to 80.7 in (205 cm).
Foam flooring tiles are easy-to-assemble and do what they suppose to do. The product makes sitting in the hot tub comfortable and provides insulation.
The product goes in two thickness options 1/4″ and 1/2″. The latter one is better for more insulation and durability.
If you look for better protection of the hot tub button and want to save money on preventing heat loss then you can buy a thicker alternative.
Many owners use ProsourceFit Extra Thick Puzzle Mat to protect their hot tubs from hard surfaces as this product is made of durable EVA-foam and goes in two thickness options 3/4” and 1”. Moreover it is waterproof.
Compared to the CosySpa Hot Tub Flooring Protector you can also adjust the size of the pad and cut through it easily. One pack of 72 pieces is enough to cover 8’*8’ area.
Choosing the base type and its construction are aspects you should consider before installing the hot tub. The main rule for any base is to be solid and level to support the hot tub weight and prevent cracking.
Along with traditional concrete slabs, some options can save you time and money. For example, gravel and pavers are cheaper and give good drainage. A wooden deck is an elegant and comfortable solution. Prefabricated spa pads save you time and money on construction.
If you prefer an inflatable hot tub, then you can place it on the smooth ground for a short-term stay. However, it is better to prepare a sturdy base to avoid any problems. Bury in mind, that you will need to buy a mat to protect the bottom from damage and decrease heat loss.
It depends on what you expect from the hot tub base. If you look for something simple and durable then you should choose between a concrete or gravel base. If something authentic then the pavers or wood deck is your favorite. If you don’t want to put much effort and time into construction then the prefabricated base is a must.
You can put a hot tub on concrete, pavers, wooden deck, prefabricated bases, and gravel. If you look for a short-term placement you can set it up even on gravel. Bury in mind that you need to put the inflatable hot tub on the protective and insulation mat made of foam.
No, one exception is inflatable tubs for a short-term stay. The ground is not solid enough to support the weight of the hot tub without deformation. While the surface becomes uneven it causes additional pressure on one side of the hot tub frame. As a result, it can crack the spa and void the warranty.
Sand is not the best option for the hot tub base. It is easily displaced and washed out with water and winds. As a result, the surface becomes uneven which may crack the hot tub.
Only in some cases. Firstly, you should be certain that the place is leveled. Many patios are built a little pitched for better drainage. This is not acceptable for a hot tub. Secondly, the foundation of the patio should be strong and thick to support the weight of the hot tub. If you have any doubts, it is better to make a new base.
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