Installing A Hot Tub On Your Deck: Things To Consider

Many Australian homeowners would agree that a hot tub is an awesome addition to a timber deck. Alongside other deck features like lounge chairs and barbecues, a hot tub can give you the perfect set-up for parties and socialising outdoors, but it's important to make sure you install the equipment correctly. If you're thinking of installing a hot tub on your deck, carefully consider the following things.

Structural integrity

Hot tubs are heavy! An average-sized hot tub full of people and water represents a significant weight, so it's important to make sure your deck can cope with the mass you're about to add. There are some rudimentary calculations you can do to give you an overall idea.

The crucial measure is the design load that the deck can cope with, normally measured in pounds per square foot. To calculate this measure, you must add the dry weight of the hot tub to the weight of water when loaded (roughly 8.3 pounds per gallon) plus the weight of the maximum number of occupants. You then simply divide this by the surface area of the hot tub to calculate the design load the deck needs to support.

Many deck builders offer online calculators to help you work your way through these calculations, but unless you're a budding structural engineer, it's a good idea to get a deck builder to do this for you. Even a minor calculation error could result in an unsafe structure.


Australian safety regulations apply if you decide to build a pool or spa with water deeper than 300mm, which will apply to most hot tubs. These regulations exist to cut the risk of accidental drowning, particularly for children who can easily fall into an unsecured pool or spa. Accordingly, you will often need a building permit to install a hot tub on your deck. You may also need to register the spa with the local authorities.

Check out the regulations that apply where you live through your local Fair Trading department. You may find some information online. Alternatively, a deck builder can help you understand how to navigate these requirements.

Power supply

You'll need a safe electrical supply to the hot tub or spa, so you'll also need to enlist the help of a qualified electrician, too. Some deck builders are also licensed to do the electrics for you, so it's worth asking about this as part of the overall design.

You'll need an emergency shut-off within a safe distance of the hot tub, in case there's a problem. You'll also need a ground-fault circuit interceptor (or GFCI), which shuts down the power immediately if it detects any variance in the electrical flow. Engineers will also need good access for maintenance and repairs, so make sure you consider this in the layout design.

Location design

You will need to consider the best place to install your spa. It's important to get the placement right. The position of the hot tub can affect ventilation, access, safety and the level of comfort the occupants will experience.

Things to consider include:

  • Prevailing winds. If the spa is near the corner of your house, the wind may feel stronger, which could spoil the experience.
  • Traffic flow. A hot tub may sit nicely in a corner, but if it's difficult to get to, it may become a nuisance.
  • Privacy. Do your neighbours want to continually see you and your family sat in the hot tub? Will the elevated position overlook people next door? You may need to consider a privacy screen or some other design element to protect privacy.

You should also think about the view. It's great if you can see your hard work in the garden, but don't let the spa interfere with what you can see from the garden.

A hot tub can make a great addition to a deck, but you need to design the installation carefully. Talk to a professional deck builder for more tips and advice.