One thing that most hot tubs have in common is their weight. No matter where you choose to position your hot tub, the site has to be able to support the weight of the tub, the water, and the people in it. The base for your hot tub doesn’t just have to be strong, it must be capable of accommodating all the necessary plumbing and electrical installations as well.
Installations indoors nearly always use a cement pad on which to base the hot tub. The cement has to be poured into an area that will be dictated by the plumbing installation. The cement pad will be poured and the hot tub settled on top of it. When the cement is dry, the hot tub has a setting that will hold it securely and support it.
Outdoors and, occasionally even indoors, a base can be made with cement pavers. It is important to recognize that most hot tubs don’t have a perfectly flat bottom, so when pavers are used they will still need to have a layer of cement over them to hold them in place and take up the shape of the base. Make sure that you take the time to compact the ground beneath the pavers enough to support the new weight.
For outdoor hot tubs, gravel beds are a definite possibility. Adequate precautions have to be taken to ensure that the gravel will not settle or move. The gravel will conform to the base of the tub and hold it in place. There must be adequate drainage to prevent any danger to the tub. Access to the tub should be easy. The area around the tub should have low-level showers so that you can wash your feet and prevent dirt from being tracked into the hot tub.
If your hot tub is going to be situated outside in a specially built enclosure, it could sit on a concrete foundation. It might need a shallow bed of sand to fill the spaces and shapes on the bottom of the tub. The concrete foundation should be about six inches thick to take the weight.
There is a system of interlocking pads that can be used to create a base on just about any surface that is compact and even. These are claimed to be as effective as poured concrete but a lot less expensive.
Hot tubs are very popular additions to decks. The very first thing you have to do when considering installing on your deck is to make sure it can support the weight. If you have any doubts at all about the strength of your deck, it is much safer to call in an engineer and have him calculate your deck strength to make sure it will support the tub.
It isn’t just the strength of the floor level deck that has to be considered, but the strength of the uprights that support the deck. A lot of weight on one side could cause the deck to lean.
However you plan your base, don’t forget that the base also has to accommodate the plumbing and electric lines. It's almost time to start enjoying your hot tub!