DIY Cold Plunge and Hot Tub Combo: Kyle’s Backyard Wellness Centre

Last updated: September 2026

A DIY cold plunge and a hot tub combined? Is that even possible? It certainly is, and in this case study I’ll walk you through a project I designed for Kyle in the USA.

The requirement

Kyle contacted me a while back about designs for a hot tub that could be converted into a cold plunge and back again, for the wellness centre he was building on his property.

I’m calling it a wellness centre rather than “an extension” because, as you’ll see in the pictures below, the end result, with its cold plunge, sauna and steam room, looks more like something from a high-end hotel than a backyard.

Kyle knew what he wanted. He gave me a spec that included massage jets, the ability to stand up in the cold plunge and, of course, the ability to switch between hot and cold. He asked me to design it, and I created the concept below.

The build

Along with the design, I supplied all the parts Kyle needed to build his cold plunge-come-hot tub. There were several stages, so let’s get right into it.

Breaking ground

The first job was to dig the hole and form it up, so the plumbing could go in. This was done right at the start, and I’ll admit the setup looks a bit strange at this stage.

Forming the walls

This was a poured concrete tub, so the next step was forming up the walls. That means putting up shuttering for the walls, and the plumbing has to go into the walls at this stage too, as you can see in Kyle’s picture below. For how poured concrete compares with block and ICF, see hot tub wall construction: what are the options?

Pouring the walls

With the plumbing in, the walls were poured. You’re probably wondering what on earth is going on by now, but trust me, the result will blow you away.

Completing the structure

Once the tub had cured, the team poured the rest of the concrete, and it started to look much more like you’d expect a hot tub build to look.

The next step was building the structure for the wellness centre itself. Here are the wooden walls going up.

The control room

Once the building was watertight, Kyle started installing the control room.

As you can see, there’s a spa pack for electric heating and a big chiller to cool the water for the cold plunge. That gives you the best of both worlds in one tub. Heating on electric will take a few hours, or maybe a day or two from cold, but it will get the water up to the 102–104°F (39–40°C) you expect from a hot tub.

If you’re planning something similar, my guide to building a DIY cold plunge pool covers sizing, walls, choosing a chiller and safety, and hot tub heaters explained covers the heating side. The control room position guide is worth a read too.

Finishing up

With the control room done, it was time for tiling and furnishing. Kyle chose a beautiful design, and he and his team got the tiling done. The result is shockingly good.

The end result

After all that work, Kyle finally saw the fruits of his labour, and his wellness centre exceeded expectations. Take a look.

Kyle got his dream wellness centre: a stand-up cold plunge that can be heated as a hot tub too, with the massage jets he wanted. And he added a sauna and a steam room to the mix.

Are you taking bookings for your wellness centre, Kyle? It looks absolutely stunning. Just wow!

Planning your own hot and cold setup?

Kyle went for one tub that does both. The other route is two separate tubs side by side. If you’re weighing that up, see hot tub vs plunge pool: which should you build? and Patrick’s basement hot tub and cold plunge build. My plunge pool guide covers sizes, costs and safety.

If Kyle’s build has inspired you to create your own hot tub, cold plunge or anything in between, I can design it for you with my custom hot tub design consultancy, or turn your own layout into architectural CAD and a 3D plumbing design. You can sketch your idea first in the free Tub & Pool Designer Pro software.

For more case studies like this one, check out my YouTube channel.

What do you think of Kyle’s wellness centre? Let me know in the comments below. I read them all.

Cheers,
Andi

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Thanks - Andi

 

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.

Fast forward to 2025, I've helped over 1400+ DIY customers just like you all over the world build hot tubs and pools. Have a good look around the site, there are lots of resources here. Please do get in touch if I can help you. - Cheers, Andi