Typically, the majority of hot tubs and swim spas are located outdoors, with a small minority installed in a building of some kind. Regardless of location, they must always be installed on a firm, level base which is capable of supporting the weight of the hot tub, the water and the bathers without risk of movement. However, there is a growing trend to have hot tubs landscaped into the garden, to take advantage of the aesthetics of a garden’s natural contours, to make them easier to get in and out of, and so that they are less imposing on the overall view. Such an installation requires having the hot tub partially, or fully, lowered into a recess in the ground. If you are considering this kind of installation, it is important to give consideration to a number of important factors, to ensure a trouble-free installation, as well as on-going service and maintenance.
The foundation the hot tub sits on at the bottom of any excavation must still be flat, level, not shift under load and be capable of supporting the considerable weight of the hot tub, the water and a full complement of bathers (typically a floor loading of well over 500kg/m2).
Even if you consider the surrounding ground to be solid, always build concrete retaining walls, and tank them with a suitable waterproofing material to prevent the ingress of ground water into the pit that the hot tub is sitting in. A reputable hot tub retailer or reputable builder will be able to give you advice on doing this.
Ensure there is adequate ventilation in the recess to allow sufficient airflow to keep pump motors cool and prevent the build up of humidity. In the event of heavy rainfall or a major leak in the hot tub, the recess could easily fill with water, flooding the hot tub’s equipment and causing expensive damage. Therefore, any excess water needs to be taken away and measures should be taken to facilitate this, such as a suitably sized drainage channel built into the floor of the recess and discharging to a lower point; or the construction of a sump below the floor of the recess fitted with one or more float switch operated submersible pumps, which are fitted in such a way as to discharge any water well away from the hot tub.
The electrical connection point is also important as this must be sited as high above the recess floor as possible, to keep it well above the level of potential flooding. It is recommended that any submersible pump is installed with its own dedicated RCD protected supply to prevent the possibility of the house electrics being tripped out by the hot tub. The 16th Edition IEE Electrical regulations provide greater detail, and it is very important that a suitably qualified electrician carries out any electrical work and is able to sign off and certify any electrical installation to Part P of building regulations. Many reputable hot tub companies have their own in-house qualified electricians, but check with them first to make sure.
Like any piece of electro-mechanical equipment, at some point in the future your hot tub will require service or repair, so think about making access to all sides of the hot tub as easy as possible. This is particularly important with a hot tub partially or fully sunk in ground. If at all possible, build the recess with a void large enough all round to get an average size hot tub engineer in, and with modular removal sections on all sides, supported by a suitable, and equally modular and easily removed, frame.
Bear in mind that hot tub engineers charge for their services by the hour, so if they have to spend the first 2 hours dismantling decking or even lifting a hot tub out of a recess, then that could make what may otherwise be a quick and simple repair more expensive than it should be. The other thing to be mindful of is that the majority of parts and labour warranties on hot tubs cover the time it takes to diagnose a fault and make the actual repair. Most warranties have clauses which allow the service company to charge for the time it takes to gain access to the hot tub if they deem it unreasonable.
If you are intending to use wooden decking, it is important to ensure the timber selected is suitable for use in a wet environment.
When purchasing your hot tub or swim spa, it is strongly advisable to notify your insurance company to ensure that it is covered through your home owner’s insurance policy. As a single high value item, many insurance companies require specific notification and details in order to provide cover.
By following the advice above, in conjunction with discussing your plans with a hot tub retailer who is a BISHTA member, their experience is invaluable, you should benefit from a trouble-free installation, leaving you free to relax in the warm, soothing waters of your new hot tub or swim spa!
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