If you guys know me then you know that I’m not a fan of a DIY cold plunge pool. I’m a hot tub kind of guy and I like my water bubbling. Freezing cold water is not for me! However, there are many of you DIYers that are looking to build cold plunge pools.
In this article I will cover what you need to think about in your designs when designing and building a DIY cold plunge. Once you’re done with this article, you’ll know everything there is to consider before getting started.
Before we begin, let me clarify that the DIY Cold Plunge pools that I’ll be talking about are not modified bath tubs filled with ice or cold water. I don’t do that because I feel jets, pumps and filtration are what define a hot tub.
The setups I’ll be referring to are full on “spa-like” pools that are chilled down using a physical chiller. They are also filtered so are not single use and have water being turned over by a pump to keep it fresh and healthy.
With this out of the way, lets get into the key consideration when building a DIY cold plunge.
How Big Should a DIY Cold Plunge pool be?
The size of your cold plunge pool is directly connected to how much space you have available. You also need to consider how many people will be in the pool at once.
Unlike a hot tub, cold plunge pools are usually not communal areas and you would not be sitting in there with friends or family having a drink. Cold plunge pools tend to be smaller and are usually designed just to be big enough for one or two people.
A smaller cold plunge is also easier to chill down and costs less to run which can add up in the long haul.
In terms of the layout, the norm is to not have seating in the cold plunge. This is dictated by the fact that most people prefer to stand or lie down in their cold plunges rather than sit in them. However, I’ve seen a few examples of cold plunges in 2024 that do have seating on them.
What should I build the walls of the DIY cold plunge pool out of?
Poured Form
Pouring a form is where you are creating a mould out of wood and then filling the mould with concrete to create your walls and seats. This is a popular way of constructing a cold plunge. If you do opt for this method, make sure that you brace the walls correctly as the last thing that you want is to have curved walls when you are done!
There is a huge amount of weight and pressure that is created when you pour the concrete so you need a lot of bracing in order for this to work. The end result is a perfectly cast cold plunge shape. This is a great way of doing things as you are embedding all your plumbing in advance so fitting the plumbing itself is easier.
You also get a good seal around all of the plumbing components so there are less chances of leaks when you use this method.
Type of Spa Construction
Concrete Block Cavity
One of the main challenges in building a DIY cold plunge is ensuring the walls have the necessary strength to withstand the pressure.
Concrete blocks are arguably one of the easiest and most reliable construction methods for this purpose. However, if you choose this approach, it’s important to incorporate a cavity within the wall structure. This cavity serves multiple purposes: it houses your plumbing, provides space for insulation, and allows for the inclusion of a rebar framework to enhance the overall strength of the construction.
The downside to this method is that it results in a relatively wide wall. For example, with a 4-inch block, a 6-inch cavity, and another 4-inch block, you’re looking at a minimum width of 14 inches. When you add a capstone on top, the final result can be both sturdy and visually appealing.
Inside the cavity, you’ll accommodate your plumbing, insulation, and rebar, as illustrated below. To complete the build, the cavity is filled with concrete, which must be properly vibrated to ensure a solid and even fill. This method offers a strong and well-insulated cold plunge structure.
CMU Block
CMU blocks are the hollow concrete building blocks you commonly see in construction. These are a cost-effective and reliable option for creating a strong structure for your cold plunge. They are widely used in construction due to their affordability and durability.
As shown in the cross-section diagram below, metal rebar is an integral part of this construction method. The rebar is embedded into the poured concrete base and extends into the walls, ensuring that the entire structure is securely tied together.
It’s recommended to reinforce every other hollow core of the CMU blocks with rebar, as this connects all the blocks to form a cohesive and robust structure. Once the blockwork is complete, the hollow cores should be filled with concrete to provide additional strength and stability.
The diagram also shows horizontal ties, which are optional but can add further reinforcement to the walls if desired. This method not only enhances the structural integrity of your cold plunge but also ensures a durable and long-lasting build.
ICF Block
Insulating Concrete Form (ICF), or Insulated Concrete Form, is a system of formwork used for reinforced concrete construction. These forms are made of rigid thermal insulation, which remains in place permanently to serve as the interior and exterior substrate for walls, floors, and roofs.
The ICF system consists of interlocking modular units that can be dry-stacked without the need for mortar. Once assembled, these forms are filled with concrete, creating a sturdy structural framework. The interlocking design is reminiscent of Lego bricks, making the process straightforward and efficient.
ICF construction has gained significant popularity in both low-rise commercial and high-performance residential projects. Its adoption has been accelerated by increasingly stringent energy efficiency requirements and the need for buildings to withstand natural disasters. This method not only enhances structural integrity but also provides excellent thermal insulation and long-term energy savings.
ICF Block cold plunge
This is a quick and easy way of building your hot tub or plunge pool. The structure and the strength are already there for you. The main downside is the cost. ICF can be much more cost prohibitive than the other options mentioned.
In ground Cavity
I’ve done a number of projects of late where there has already been a hole in the ground that the customer wanted to convert into a hot tub. This is totally fine of course. Perhaps there has been a sunken plastic shell tub that you are replacing – this is when this kind of a method would come to light.
The drawing below shows what the construction would look like. You can see that there is a 6” cavity with a 4” block. The cavity will be filled with concrete once the plumbing is in place.
Which Method Do I opt for?
Ultimately, this is down to personal preference, material availability, skill set and budget. All of these methods I have highlighted above produce a fantastic end result. The cold plunge that you are dreaming of! However, each has their challenges so ultimately, you will pick the method that best suits you, your location, skillset and budget.
You can check out my detailed article on how to build your own DIY Cold plunge pool here.
What plumbing considerations do I need for a DIY cold plunge pool?
Again, I’d like to point out that the DIY Cold Plunge Pools that I design are not just ice baths – they are fully filtered, chilled with a physical chiller and the water is turned over to make sure it is not a single use pool.
You will need a pump, a filter two inward suction drains and also two returns. These should be connected through a chiller
What are the health benefits of a DIY cold plunge pool?
Again, I’m a hot tub / plunge pool designer so I am definitely not qualified to talk about the health benefits. However, I did do some research for this article so thought I would include them anyway – just to be clear they are coming from much more qualified sources than me!
Why Should You Try a Cold Plunge?
There are several reasons why you should try out a cold plunge pool. First, it’s a great way to relax and unwind after a stressful day. Second, it helps reduce stress levels. Third, it improves circulation. Fourth, it reduces muscle tension. Fifth, it promotes better sleep. Sixth, it relieves headaches. Seventh, it boosts energy levels. Eighth, it strengthens immunity. Ninth, it helps with weight loss. Tenth, it improves digestion. And finally, it helps improve mood.
How Does a Cold Plunge Work?
The cold plunge pool works because water temperatures drop below body temperature. This triggers the release of endorphins, which are natural painkillers. Endorphins also help relieve anxiety and stress.
A cold plunge pool is a simple way to get yourself into shape without having to go to the gym. You simply jump into a deep pool of ice-cold water and stay there for at least five minutes. During this time, your muscles contract and relax, causing them to burn calories. In addition, the cold water stimulates blood flow throughout your body, helping to increase metabolism.
Is It Safe?
While there are some risks associated with using a cold plunge pool, these risks are minimal. In fact, the benefits of a cold plunge pool far outweigh any potential risks.
The first thing you should know about cold plunge pools is that they aren’t dangerous. There are many different types of cold plunge pools available, and most of them use water temperatures between 50°F and 60°F. If you choose to use one of these pools, be sure to follow the manufacturer’s instructions carefully. You should never leave children unattended in a cold plunge pool, and you should always supervise anyone who uses a cold plunge pool.
How Long Will It Take To See Results?
If you use a cold plunge pool regularly, you should see results within two weeks. However, it takes longer than that to see real changes in your body. You might notice an improvement after just one session, but it will take several sessions before you start seeing significant improvements.
The cold water shock helps to increase blood flow throughout the body, which improves circulation and increases metabolism. In addition, the cold temperature stimulates the lymphatic system, which helps remove toxins from the body.
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Hi, Andi here. I own Buildahottub.com and also write all of the articles and info pages on the site. Some years back now, I built my own hot tub but struggled to find the information I needed. So, once my tub was complete, I started this website to help others in their own pursuit of hot tub and plunge pools DIY building information.
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