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A hot tub is an excellent feature to have on your property. A relaxing soak is a great way to melt away the day’s stress regardless of what time of the year. Hot tubs are good for your mental and physical health and may even improve your home’s value. But that is only if you choose the right hot tub base. When planning to install a hot tub, homeowners often spend much time shopping for the right hot tub. But Keyrenter Premier Management warns that choosing the suitable base for your hot tub is more critical than the type of hot tub you buy.
The most common base used for hot tubs is a concrete slab. Why does your hot tub need a base in the first place? How thick should you make that concrete slab? When choosing a base for your hot tub, are there alternatives to a concrete slab? Find the answers to these questions below.
Do you have to install a concrete slab for the hot tub?
Actually, you don’t, but it is highly recommended. You can many different materials as a base for your hot tub; a gravel bed, wooden deck, spa pad, or paver stones. But given the weight of the tub and the fact that it will hold water, a concrete base is the best option.
An average hot tub weighs as much as 115 pounds per square foot. The base you use for the hot tub must be rated to withstand this amount of pressure. It should be stable, level, and not prone to damage by heat or water. Think about this when choosing a base for your hot tub.
Placing a hot tub on a wooden deck exposes the deck to the possibility of damage. The deck may weaken under the weight of the tub. On the other hand, a concrete slab ensures that your hot tub is entirely level and strong enough to hold the weight of the tub.
How thick should a concrete slab be to hold your hot tub?
Concrete is a versatile material that can be used as a base for almost anything. In addition to supporting your hot tub, a concrete slab will also improve the value of your home. Moreover, unlike wooden decks, concrete does not need maintenance after installation.
A hot tub base should be strong enough to bear up to 115 pounds/SQF. To withstand this much weight, the concrete slab should be a minimum of four inches thick. But beyond its thickness, other factors influence the strength of your concrete slab.
The concrete slab must be completely level. If a slab is not level, it does not matter how strong it is. A concrete slab that is out of level will inflict structural damage on your hot tub, with the result that you will not be able to enjoy the tub for as long as you should.
Second, the concrete slab must be allowed to cure properly before you put any weight on it.
Although a concrete mix will become solid shortly after you make it, this does not mean that the concrete is actually strong enough to bear significant weight.
Concrete cures through a chemical reaction between the water and cement. This process binds the concrete’s components to make a strong bond to cure fully concrete needs for up to four weeks. The concrete will crack if a hot tub is installed before it is cured completely.
How to make a concrete slab
Remember that your slab has to be four inches thick (it is okay if it is thicker, more is usually better). This means that to make an 8×8 slab, you need enough concrete to fill around 21.33 cubic feet of space or 36 bags of QUIKRETE (80-lb bags).
To build the concrete slab for your hot tub, follow these steps:
1. You may pour the concrete directly on the dirt. If you do this, make sure you first remove the top layer of loose soil on the ground and any organic material on the surface. Dig deep enough until you reach the firm earth below.
2. Alternatively, you can install your concrete slab on a bed of gravel. The gravel should be four inches deep, and you must do the above step before laying down this gravel bed.
3. Next, build a frame using 2×4 lumber. Make sure the sides of the frame are braced to keep them from bending under the weight of the concrete.
4. As an optional addition, you may add a grid of size #3 rebar inside the frame to give your slab more stability. This is not completely necessary but highly recommended. Adding steel reinforcements prolongs the life of the slab.
5. Finally, pour the concrete and screed, and finish it. Leave it to cure for the required number of days, and don’t forget to wet the concrete often to facilitate the curing process.
Prefer to hire a professional to create the slab for your jacuzzi addition?
We may be biased, but we highly recommend hiring skilled professionals. Get in touch with Jorge and his team at JM Concrete Pros to discuss your concrete needs in more detail today!
Hot Tub Concrete Slab: Quick FAQs
How thick should a concrete slab be for a hot tub?
For most hot tubs, pour a concrete slab at least 4 inches thick. For larger or heavier spas and swim spas, use 6 inches reinforced with rebar or wire mesh. A filled hot tub can weigh 3,000 to 6,000 pounds or more, so size the slab to the fully loaded weight.
Can a 4-inch concrete slab hold a hot tub?
Yes. A properly poured 4-inch slab over a compacted base supports most standard 6 to 8 person hot tubs. For oversized spas, swim spas, or weak soil, step up to 6 inches with reinforcement.
Do I need rebar or wire mesh under a hot tub pad?
Yes. Reinforcement with rebar or wire mesh helps the slab carry the concentrated load and resist cracking, which matters in the expansive soils and high heat common across the Phoenix East Valley.
How long should concrete cure before placing a hot tub?
Wait at least 7 days before setting a hot tub on a fresh slab, and ideally 28 days for full cure strength. Your contractor can advise based on the mix and weather.
What size should a hot tub concrete pad be?
Pour the pad slightly larger than the hot tub footprint, usually 1 to 2 feet beyond each side, for safe access and full support.