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Sinking your hot tub or swim spa

If your hot tub or swim spa will be installed into a deck or below ground in a pit, there are some things you need to be aware of – as we explain below.

Building a hot tub or swim spa into timber decking or below ground in a pit, are two of the most common types of hot tub and swim spa installations.

Whether you choose to place your new hot tub or swim spa in a deck or in the ground, there are some things you need to know before starting your project.

Building a deck for a hot tub or swim spa A deck can be an excellent location for your new hot tub or swim spa. You can install the hot tub on top of the deck or have it semi or fully built into the deck. We’ve highlighted below the key things to discuss with your builder when designing and building a deck for a hot tub or swim spa.

When it comes to decking–regardless of the size, layout or design–for safety and compliance purposes, Wyre Forest Spas requires that all decks built for hot tubs or swim spas are designed and built by a registered builder. Also, remember that each spa installation is different and so there may be different or additional requirements we haven’t mentioned. Always consult your builder.

Top 5 things to consider: 1. Install the spa before completing the build. It is best to leave the top portion of the deck un-built before hot tub or swim spa installation. It is much easier building the decking boards up to the spa than trying to lower the spa into a hole on delivery day. 2. Test the spa before installation During shipping and handling some of the components may have shifted. Please ensure the hot tub or swim spa is tested for at least 48 hours before installing any decking around it. Even though all units are tested in the factory, some transport or site handling damage may occur and we suggest you make sure that no leaks appeared and the spa is operating correctly before finalising your installation. 3. Choose the right foundation for the spa height. For the base or foundation, depending on how high you want your spa to sit out of the deck, you may choose to put it onto a concrete slab or you may need to build a smaller deck to sit the spa onto to get your desired height.

If you are building a small deck to sit the spa on, please ensure you have consulted with your builder or engineer on the design before building.

4. Leave space between the decking and the lip of the spa. We do not recommend running the deck boards flush with the underside of the spa shell. Instead, we recommend that you position your spa to sit at least 400mm above the deck height to the top of the spa. This allows for safe entry and exit into the spa and most importantly, allows for the cover safety clips to be attached to the spa's cabinet. If your spa shell is level with the deck you will need to install these clips onto the deck and they become a toe and trip hazard, typically ending with either a broken toe or broken clip. Finishing the lip of the spa to the top of the deck is not recommended, primarily because the spas are hand-trimmed and we would never be able to provide you with an exact measurement for the shell to finish level with the deck. Also, if you have any settlement in your foundations and the shell comes to rest onto the deck, it could cause structural damage to the shell that would not be covered by warranty. Note: If you are decking up to the side of the spa, you may have to cut the door panels before the deck is installed. The door panels will need to be removed and cut below deck height by your builder so that the lower section can be removed for service access while the top section (above deck height) can remain fixed in place.

5. Make sure you can access the equipment For serviceability, you will need to provide access to the spa’s equipment, electrics and plumbing.

Sinking a spa or swim spa below ground in a pit There are many considerations when installing a hot tub or swim spa below ground level. Remember, before installing any hot tub or swim spa below ground – you must consult with your local builder for help and guidance on how best to construct the deck and to have your groundworks done correctly.

Can my hot tub or swim spa go in the ground? Yes, however you need to consider the site and consider a number of steps to ensure that your spa will continue to work correctly and be maintained. Here are some helpful tips:

  • Be sure to have enough space around the swim spa for any access purposes.

  • Ensure that all the controls, pumps, heaters and plumbing can be accessed through the panels under the spa.

  • It is critical that you allow for a drainage pit. A pit measuring 1 metre x 1 metre is adequate. As an example, a 4 metres x 2.3 metres swim spa will need a hole size 5.5 metres x 3.3 metres as a minimum with another 1 metre x 1 metre hole for drainage.

Top 5 things to consider before you begin:

1. Excavation and disposal of the soil

You will need to ensure there is adequate access to your property for excavation equipment.

Make sure you do not excavate too close to buildings or structures as there may be a risk of undermining the foundations.

2. Retaining walls

Depending on the depth of your excavation and the required height of your retaining walls, engineering and local council permission may be required.

3. Drainage

Flooding is not covered under warranty so please read this section carefully.

Adequate drainage needs to be installed to prevent the spa equipment from being flooded and your warranty voided.

If your pit has retaining walls on four sides, then it will drainage installed.

It is recommended that you install a number of strip drains in the pit slab directing water to a drainage pit/soak away.

4. Equipment access

Make sure to consider the service access for your spa so you can easily repair or replace any parts or equipment. Without easy access to equipment, your service provider may have to remove the entire hot tub or swim spa for maintenance and service.

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