Posted by Alex Clamp in
Hot Tub Installation Guides
on 21st February 2023
A standard five-seater hot tub weighs around 2,000kg when it’s full of water and people.
Failure to create a flat surface and 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 as hot tub owners to create a solid foundation for a home hot tub that perfectly complements your property.
You’ll need a sturdy spa foundation in place to install your new hot tub 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 the delivery day to identify possible locations for a home spa on your property and the most appropriate hot tub foundation 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 appropriate 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.
Here’s a quick rundown of the kinds of bases you can install your hot tub 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 slab foundation into the ground or give it a deck or patio trim so it looks the part, too.
Concrete slabs do offer a very solid base and reliable foundation that can offer good insulation, however, a concrete base is often more difficult and time-consuming to install and prepare when compared to other hot tub base options. Additionally, a concrete foundation may not offer the flexibility needed for a non-permanent installation.
If you do opt for a concrete base, make sure the concrete slab is at least four inches thick and slightly sloped so rain water runs off it rather than pooling under your hot tub.
Placing your hot tub on decking is certainly an eye-catching way to display it. Plus, the wooden deck is 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. A wooden frame / wooden base is 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 a gravel base. Plus, getting the gravel completely flat onto a level surface can be a headache, and having to step out of your spa onto a gravel hot tub base with bare feet can be painful or even lead to injury.
Paving stones make for a particularly attractive base and sturdy foundation for your 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.
A foam hot tub pad won’t support a hot tub’s weight 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.
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 ambience 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 per cent recycled plastic.
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 far from ideal.
Plus, if you place a hot tub 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.
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.
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.
Hot tubs should sit on a flat, level, and sturdy surface. The base should be able to support the weight of the hot tub when it’s filled with water and people. It’s important to choose a base that will provide adequate support and prevent any shifting or settling over time.
A hot tub base needs to be level, but it does not need to be perfectly level. While a slight tilt in the base can make it difficult for water to be evenly distributed around the inside of the hot tub, as long as it’s still relatively close to level then this shouldn’t pose a major problem.
On the flip side, a poorly levelled base can lead to a hot tub rocking, which can not only be a nuisance but can cause damage to the hot tub itself and can even result in injury if strong enough.
To avoid these risks and guarantee a safer use environment for your hot tub, aim for as as-close-to-perfectly-level base as you can manage.
Inflatable hot tubs should not be placed directly onto the ground, but rather on a flat surface such as concrete, paving slabs, or hot tub tiles. To ensure it is level and to protect it from debris, you may also wish to use a foam hot tub pad underneath inflatable tubs.
Yes, when paired with hot tub mats, spa pads and pavers. Inflatable hot tubs are only permitted on gravel bases with additional protection such as insulation mats. The gravel offers excellent stability during hot pools and levelling and the spa pads provide extra insulation and protect the tub’s surfaces from damage.
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.
Find the best hot tubs across every price range with the WhatSpa? Hot Tub Buyer’s Magazine. The latest edition includes the latest WhatSpa? Hot Tub Best Buy Awards. Request your free magazine now!
Note: When you purchase through links on our site, we may earn an affiliate commission.
About the author
I am the Content Writer and Marketing Officer at WhatSpa? Magazine. I have worked at WhatSpa? for over 8 years, and I recently graduated with Distinction from Northumbria University with a Master's degree in Occupational and Organizational Psychology. My role at WhatSpa? is to ensure that all hot tub lovers can easily access the highest quality and most up-to-date content, news and information from within the UK wet leisure industry.
Read our hot tub buying guide to learn how to choose the perfect hot tub model, then get the best deal from a quality hot tub retailer.
Read our guide to choosing the right type of housing for your hot tub and what you need to consider.
Read our guide on buying a hot tub for a small garden.