Hot tub base guide 2022

Posted by Nick Clamp in Hot Tub Installation Guides on 12th February 2022

A standard five-seater hot tub weighs around 2,000kg when it’s full of water and people.

Fail to create a solid foundation for that kind of weight and you could run into serious trouble. Before the hot tub installation process is conducted you need to draw up your plans to create an ideal hot tub base for your hot tub to be sited.

Here’s everything you need to know to create a solid foundation for a home hot tub that perfectly complements your property.

Installing a hot tub base: The basics

You need a sturdy base in place to install your hot tub on before you can think about having it delivered.

Buying from a WhatSpa? Approved supplier is worth its weight in gold here. All of these dealerships will survey your property ahead of delivery day to identify possible locations for a home spa on your property and the most appropriate bases of different kinds.

A quality supplier will also look after the hot tub’s electrical installation, which often has a big impact on the base. For example, any outdoor cabling linking your hot tub to a dedicated power supply needs to either be steel-wired armoured (SWA) cable or protected by PVC piping, which will need to be installed below ground alongside the base. 

So, be sure to take your hot tub dealership up on their offer of a site survey to make sure there’s a suitable foundation for them to install your home spa on. Otherwise, you could end up with a serious headache if the delivery team turns up and can’t find anywhere appropropriate to put your hot tub.

If your supplier isn’t prepared to provide this guidance and conduct a professional hot tub site survey then we’d strongly recommend that you move on and find another respected dealer who will offer this as part of their service.

The types of hot tub bases

Here’s a quick rundown of the kinds of bases you install your home spa on so you have an idea of what your options are. 


One of the most common hot tub bases is a simple concrete slab. This provides a strong, durable, and relatively cheap foundation for even the biggest of hot tubs. You can also sink a concrete foundation into the ground or give it a deck or patio trim so it looks the part, too.

However, a concrete base is more difficult and time-consuming to install than other options.

If you do opt for this hot tub base, make sure the concrete is at least four inches thick and slightly sloped so water runs off it and rather than pooling under your spa.


Photo © Urban Cedar

During the past

Placing your hot tub on decking is certainly an eye-catching way to display it. Plus, it’s comfortable underfoot when getting in and out of your spa. 

However, if you’ll be building decking from scratch, it’s one of the pricier hot tub bases. It’s also the least durable option here – although you can mitigate that by going for composite decking that has a longer lifespan than wood.

The cross-members supporting a deck you’ll be using as a base for a hot tub need to be at least 4” x 2” and no more than 18” apart. That means you’ll likely have to add extra supports to a pre-existing deck you’re planning on using as a foundation for a hot tub.
A word of warning if you choose to sink your hot tub into your decking: you need to make sure the side of your hot tub that contains the access panel is accessible. It’s a good idea to install a removable section of decking for repair access that doesn’t spoil the aesthetic.


Gravel is an affordable, attractive, and durable hot tub base that’s a doddle to install. 

However, it does come with its downsides. There’s a chance your hot tub could be damaged when it’s installed on gravel. Plus, getting the gravel completely flat can be a headache, and having to step out of your hot tub onto gravel with bare feet can be painful or even lead to an injury.

Paving stones

Photo © Chiswell Leisure

Paving stones make for a particularly attractive foundation for a home spa. They’re particularly effective at tying your hot tub in with the rest of your garden.

If you already have a patio in your garden, it will almost certainly already be reinforced and level enough to place a hot tub on – although it’s well worth having your dealership double check during their site survey. This could save you a pretty penny on your hot tub installation costs.

However, having a patio installed from scratch to sit your hot tub on is one of the most expensive options. Plus, if your paving stones aren’t completely flush and fitted together properly, they could subside over time, damaging your patio and your home spa.

Hot tub pads

A foam hot tub pad won’t support the weight of a hot tub on its own. But it is an added extra that can protect your spa’s cladding from debris and rough surfaces while improving heat efficiency.

However, they’re not the best looking things in the world. Plus, they might deteriorate over time and cause odour problems with being in constant contact with water.

Plastic tiles

Prefabricated plastic hot tub tiles are affordable, easy to install, and easily adapted to any shape or size you need. You can also get them with LED lighting around the edges to provide ambiance and a bit of safety when you’re using your hot tub at night.

However, they’re certainly one of the more utilitarian hot tub base options, so perhaps not the best choice if you’re looking to create a stylish home spa retreat.

If plastic tiles are right for you, be sure to pick out a weatherproof design that’s been manufactured from 100 percent recycled plastic.

Do hot tubs need to be perfectly level?

Photo © Hot Tub Factory

Whichever material you choose to use as a hot tub base, you need to make sure it’s completely level.

First, if your hot tub is on a slant, the water will be higher at one end than the other, which is obviously far from ideal.

Plus, if you place a spa on uneven decking or paving stones its weight won’t be distributed evenly, potentially damaging its foundation over time. And your hot tub’s warranty won’t cover any damage caused by a botched installation.

Last but not least, water will pool under your hot tub if its base isn’t even, causing all kinds of problems – especially for wooden spas.

Can a hot tub be placed directly on the ground?

You can’t install a hot tub directly onto the grass or earth. This surface won’t be even, will get wet and cause damp problems, and will sink from the weight of a hot tub full of water and people.

If you’re looking for an affordable hot tub base, concrete, gravel, or hot tub tiles are all good options that won’t break the bank.

Which hot tub base is best?

All the options we’ve walked through in this short guide make for the perfect foundation for a hot tub. The best option for you all depends on what you already have in your garden, how much you’re looking to spend, and what you think looks best. 

To fully understand your options, be sure to take your hot tub dealer up on their offer of a site survey.

And if you still haven’t picked out the perfect hot tub, be sure to grab your free copy of WhatSpa? magazine for help narrowing down a shortlist of best buys and quickly finding the right model for you.

About the author

Nick Clamp

I am the Editor-in-Chief at WhatSpa? Media Group and my job is to keep you informed about the very latest hot tubs on the UK market... the best job in the world! When I'm not being deluged with press releases and hot tub brochures I enjoy keeping fit and participating in endurance events including triathlons and distance running.

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