What I’d Change If I Built My DIY Hot Tub Again

Around eight years ago, I built my own DIY hot tub. You’ve probably seen it in the background of half my videos.

Fast forward to today and I’ve helped over 1,500 people build their own, and thousands more with spare parts for fixing their existing tubs. So I like to think I know a thing or two about what works — and what doesn’t.

With that in mind, I thought it’d be worth putting together an honest post about what I’d actually do differently if I started from scratch. Because believe me, I made plenty of mistakes first time round.

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I’d use ICF instead of cinder block

My hot tub is built from cinder block. It’s a perfectly usable material — softer than a standard CMU block and widely available — but if I was doing it again, I’d go with ICF (insulated concrete form) without hesitation.

If you’ve spent any time on this blog or my YouTube channel, you’ll know I talk about ICF a lot. I always describe it as Lego for adults — and that’s genuinely the best way to put it. It’s lightweight, incredibly easy to cut (it’s just polystyrene), and simple to work with when it comes to routing your plumbing through it.

The big win though is what happens once it’s filled with concrete. You end up with something that’s both seriously strong and properly insulated. For a hot tub, that insulation matters — a lot. It’s the obvious choice and I wish I’d used it from day one.

I’d start with a dual pump system

This is actually something I’ve already corrected on my own tub during a remodel a couple of years back when I added an air source heat pump. But I had to make it work with a single pump setup, which wasn’t exactly straightforward.

With a single pump system, you’ve got one pump doing everything — low speed for heating and filtration, high speed for your jets. A dual pump setup gives you a dedicated pump for each job, and the flexibility that comes with that is well worth the extra cost upfront. If you ever want to upgrade or add equipment down the line, you’ll be really glad you planned for it.

I’d make the control room bigger

This one I talk about constantly, and for good reason — because I got it badly wrong myself.

I measured up all the kit, then squeezed it into the smallest space I could get away with. Don’t do this. I’ve since had to go back and resize my own control room, so I’m speaking from painful experience.

Make it as big as the space allows. Bigger than you think you need. Trust me — when you’re trying to get in there to service or swap out a component, you will thank yourself for every centimetre of extra room.

I’d use mosaic pool tiles instead of large tiles

The last change I’d make is to the finish. I went with large tiles because I thought they’d be quicker and easier to lay. And they were, to a degree. But over the years, I’ve seen so many customer builds finished with beautiful mosaic pool tiles, and honestly? That look is in a different league.

Yes, they cost more. Yes, they take longer. Yes, they can be fiddly. But the end result is genuinely stunning, and I think it’s worth every extra penny and hour of effort. If I did it again, I’d skip the local hardware store tiles and invest properly in the finish.

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So there you have it — four things I’d do differently. ICF over cinder block, dual pump from the start, a generously sized control room, and mosaic pool tiles for the finish. If you’re in the planning stages of your own build, hopefully this saves you from making the same mistakes I did.

Got questions about your project? Drop them in the comments or get in touch via the site — I’d love to help.

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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