John from Kentucky: An 8×8 DIY Hot Tub Built from My Plans

Last updated: September 2026

Grab a seat (preferably not a wet one… yet) and let me tell you about John’s ride into the world of homemade hot tubs. Trust me, it’s been quite the splash!

John, from Kentucky, built an 8×8, 14-jet hot tub in his backyard using one of my pre-designed plans. While many of my case studies are custom designs, this one is more straightforward, and it’s a great example of what you can achieve with an off-the-shelf plan and no custom design at all.

Digging in: the hole

First order of business for John? Digging a giant hole. He’s out there like a modern-day prospector, but instead of gold, he’s after relaxation!

Everyone’s journey starts with a hole, and John’s was no different. If you’re building an in-ground hot tub, there’s no other option. My in-ground hot tub build guide covers the dig, the base and the slab.

Walls: the world’s heaviest game of Jenga

With the hole sorted, John moved on to the walls. When I think “hot tub”, I don’t immediately think “concrete blocks”. But John had vision. He stacked CMU blocks like he was playing the world’s heaviest game of Jenga, and he put vertical rebar in them for good measure. It’s like building a fortress, but for bubbles! If you’re choosing a wall system, see building a cinder block hot tub and block, ICF or poured concrete?

The interior: where comfort meets concrete

Now we’re getting to the good stuff. John built the steps and seats out of more blocks (he really loves his blocks), and then covered the outside in insulation. He’s doing a dual-wall cavity build, a cosy cocoon that just happens to be full of water. There’s more on this in my DIY hot tub insulation guide.

Plumbing and electrical: the veins and nerves

Here’s where things got technical. John installed the skimmer and drains like he’d suddenly become a pool shark, and he ran conduit for the lights, making sure everything ends up above the waterline. Safety first! We don’t want any shocking developments in this tub. See how to install a skimmer and installing a main drain.

Concrete dreams and waterproof schemes

Next up for John was pouring the final layer of concrete, like the icing on a very heavy, very wet cake. Once that had dried, it was waterproofing time. Because let’s face it, a leaky hot tub is just a very expensive puddle.

The adventure continues…

When we last left John in July, he was forming the seats with the CMU blocks and pouring the concrete. The structural part was complete. Now the walls and plumbing are done too. The picture below shows where John’s build had got to.

The loop you can see in the picture is a Hartford loop. It stops water flowing back down the air line to the control room when the air and water mix. Otherwise your control room could flood, which is an expensive mess! You can use a thirty-dollar plastic check valve, but I like to rely on gravity to keep the water in the tub. There’s more in my hot tub air blower guide and water in a hot tub air blower.

Finishing already?

John also started on the finishes, inside and out.

Exterior

John started on the exterior skin. He’s using CMU block with cavity construction, so his plumbing and pipework run through the cavity.

This is needed because it’s an above-ground hot tub. His tub has an interior wall, a cavity with the plumbing, and an exterior wall to cover it all. That way it looks good and there’s no exposed plumbing.

Interior

With CMU blocks and mortar, the inside of the hot tub is uneven and needs rendering. John did a great job of the render, as you can see below.

The next thing the interior needed was waterproofing. Regular readers will know I recommend Hydro Ban cementitious waterproofing membrane in the USA, and Ardex S 7 Plus in the UK and Europe. There’s more in my waterproofing, grout and tile adhesive guide.

The last job on the interior is paint or tile. John is doing both: tiles on the top section and paint on the bottom half. You can see the tiles on the waterline of John’s tub below.

I always recommend a tiled waterline. It makes cleaning much easier. You can scrub a tile, but you’ll probably scrape a painted surface! See choosing hot tub tiles.

The control room

John also made progress on his control room. It’s close to the tub, only a few feet away. The closer the better, because it keeps the pressure and flow up to your jets.

If your control room is further away, you’ll need to do some calculations on pipe and pump sizes to make sure you get enough flow for the jets to work properly. See where to put your hot tub control room and how to correctly size a hot tub pump.

Then it was on to the parts. John dry-fitted everything first, to make sure it all fitted together and was in the right order. PVC cement is unforgiving. If you make a mistake, your only choice is to cut it out, so there are no do-overs! My guide to the perfect PVC solvent weld joint covers how to get it right first time.

From start to finish

And we’re back! If you know me, you’ll know there’s nothing I enjoy more than seeing a hot tub project come to life. So here’s a recap of John’s DIY hot tub build.

It all began in May 2024, when John bought my most popular model, the 8×8 hot tub. With the plans, designs, instructions and videos in hand, he was ready to get started. Meanwhile, he applied for the necessary permit, which was approved. That’s a crucial first step (see do I need a permit for my hot tub?).

John sourced all his parts from my US store, parts4tubs.com, and got to work. By June 2024, the foundation blocks and plumbing were almost complete, and the project was well under way.

By September, John had made big progress. He’d applied a skin coat and carefully rounded off the seats, bringing the tub much closer to completion.

And in November 2024, John’s hot tub was finished, and it looks absolutely stunning!

Looking at it now, it’s hard to believe this is the same build we saw at the start. And the best part? John did all of this with a ready-made design, no custom design needed. If you’re wondering how long a build like this really takes, see how long does a DIY hot tub build take?

Want to build one like John’s?

John built his from my 8ft x 8ft hot tub plans. If you’re working in metric, there’s the 2.44m x 2.44m version, and you can see every size on the hot tub plans page. Each set includes the CAD drawings, plumbing layout, parts list and video course.

What do you think of John’s build? 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