How to make a hot tub part 1 - Materials Location and Cost

11 March 2020  |  Superior Wellness

How to build a hot tub part 1 - Materials.

Building a hot tubBuilding a hot tub can be really good fun, so here are a few pointers to help you get under way from Hot Tub DIY.

Car Image

The photo to the left shows a Fiat car that was converted with our help for a promotion of 'Aperol Spritz', it consisted of car modification, fibreglass mould and a basic plumbing for jets, a heater, filtration and a pump. 2 cars where made and used on stages and in shows in and around London.

First Starting.

What is your experience of a hot tub, did you prefer a hot tub or a spa?

The difference is a hot tub is just hot water in a tub, and a spa has massage jets, however in the UK this is confused and a hot tub is seen as having massage jets and a spa is somewhere you go to get pampered.

Its possible to turn a hot tub in to a spa at a later date and best to take this into account in the early stages as you may save time in electrical equipment, a good example of this is spending on the control system to get something to manage pumps versus just getting a thermostatically controlled heater. (more of this later).

Second Location

Where is it going to be? does the location give you privacy, is it away from over hanging trees (they drop leaves in the water which get stuck in the plumbing) and will it disturb your neighbours? (people tend to be load talking over the jets).

A good location would also take into consideration access, possibly rain cover and electricity.


With the basics in mind you would now consider materials and a few other basics, building a hot tub or spa is a bit of a chicken and egg scenario in some cases, the materials define this...


If you have a financial restriction then it may help to point out building hot tubs is time consuming and costly, if you compare this to purchasing a hot tub with a thousand jets, built in tv's / stereos from a local supplier then this article may not be for you. A rough idea on pricing is very difficult when it comes to building your own hot tub where as most retailers have a price point of £4000 for a Chinese made hot tub and £8000 for an American made hot tub, which is probably still made in China.

Material types for building a hot tub.

Building a hot tub can be built out of many things, concrete, wood, metal and plastic, this material could be pre formed for example a wooden barrel, or plastic container, aluminium jet parts or even a car, however they all need to include the ability to hold water and take into consideration 'Water Volume', if you are thinking 4 people, allow space in the total height for the water to rise so it doesn't go over the edge and get waisted, unless you are planning to have a reservoir tank which is a much more complex system.


Converting a wooden barrel is the easiest method of hot tub, you can buy these online at costs from £1000 and easily convert them to give massages using jets and control systems, also you don't need to be a millionaire to build one because a basic plumbing loop starts at roughly £500 and you can add air blowers and all sorts of things as and when you want to upgrade them.

Wood frame and tile

Creating a hot tub with a wooden frame, is simple if you use a tanking method similar to wet rooms, 'Hardiebacker board' and something like a 'Mapie shower waterproofing kit', can make for a really fun project, simply tile on top with a swimming pool grout and adhesive.

If this is done well you can create a show stopper, be clever with your jet choices even maybe add light as well. You can realistically create something for as little as £800 excluding your jets, filter and electrics.


Plastic fantastic is also an option, there are loads of containers that make a fun hot tub for family or fun purposes, this could be a cattle bowl or 1 man container, anything is possible, support it with timber, insulate and of you go. Usually people that go this route already have an object in mind and then say, "that would make a great hot tub!"


This is for all you steel fabricators out there, Not sure how you would do it, however if you have the skill go for it :)

Concrete or block

Common for builders, we get asked every other day what the requirement is for building a hot tub out of concrete or block, although it sounds like the best method its also very expensive and the jet choice is restrictive due to the thickness of the walls. To see hot tubs /spas being built this way have a look on YouTube and search into Gunite jets. They tend to end up looking like a commercial hot tub, but this is ok if your building a hot tub for that purpose. Cost is probably double for all the jets but they can last 10 times longer and look just as awesome as the others if you start to design them to be built into your garden or property surrounded by rocks and waterfalls.


Lastly fibreglass, which sounds boring but when you think curves and customisation its really the material of choice. Think pond building then add jets, LED lights and a water feature, you could build something far more interesting than you can buy in the shops, that caters for specific muscle groups in the form of loungers and captain seats. Building custom Fibreglass spas is very affordable if you buy your materials from industrial suppliers and you would benefit from zero jet and component restrictions.


Insulation and covers

Lastly heating a hot tub can be expensive, filling it with water is a cost but sustaining the heat and running the pumps needs to be taken into account, so think about insulation, if outside it may need a thermal cover on top, king span insulation around the sides and so on, where as inside you are dealing with evaporation and condensation.

There are lots of things to be considered when building a hot tub, the next article is called 'How to Build a Hot Tub: Part 2 Plumbing Design and Filtration

This article was written by Jon Pennington at Hot Tub Help Limited, if you need help on components please get in touch directly at [email protected]