Alternative to Gunite? Building DIY Hot Tubs is not just for the professionals. In this blog post we’re going to look at two DIY alternatives to shotcrete or Gunite hot tubs. The methods I’ll explain are much easier and don’t require any special equipment.
If you have been searching around YouTube and you’re looking to build a hot tub or a pool, you will have come across the Gunite or shotcrete methods of construction. Now these methods of construction are really, really cool. They involve concrete being sprayed in at high pressure on to a metal rebar construction. I’m sure you’ve seen the videos.
Gunite & Shotcrete
If not, you can just Google it and you will see how these amazingly skilled people spray in the concrete. They will then trowel it all perfectly flat and you end up with an absolutely perfect finish without any joints at all. Within a day, it’s all done and you let it cure. Perfect. The only real downside to these methods is that they are not for the DIYer like you and me. They are only for the professional and require skills and machinery that most of us just don’t have.
A Little Bit of History
But before we look at a couple of options that are possible as DIY alternatives to Gunite, I wanted to delve a little bit more into Gunite and Shotcrete. Often, they are both branded as one and the same, but there are very subtle differences. Gunite was in fact the the original method. Furthermore, Gunite was trademarked in 1909 in North Carolina by a company called Allentown Equipment.
Allentown Equipment were the main supplier and manufacturer of the equipment needed to spray in the Gunite concrete at high pressure. Therefore, they thought that it made sense to trademark it. In doing so, people then needed an alternative so they didn’t infringe on the trademarked name. Rather than infringing on the trademark, they came up with a more general term called Shotcrete.
Differences between Gunite & Shotcrete
Now I’m sure that there’s some concrete guys out there that are going to find some inaccuracies with my account here. However, as I understand it, the main difference between Gunite and Shotcrete is the mix. Gunite is a dry mix, which then mixes with the water actually in the gun itself just as it is being sprayed onto the rebar.
Whereas, shotcrete is actually mixed as a wet construction and it’s then sprayed out and very similar method. But, it’s different enough so that it doesn’t infringe on that trademark. So you’ve got those two terms, which as we’ve already identified are not really for the, the DIYer. Slightly different in technicalities, but essentially the same in the way they are applied. Not for us DIYers.
DIY Alternatives to Gunite & Shotcrete
So what are the DIY alternatives to Gunite or Shotcrete? Well, the first one is a block-built hot tub. You can build out of cinder blocks or you can build it out of CMU blocks. The process is very much the same.
Firstly, you’re going to pour yourself a concrete pad or a base. This is going to be made up of maybe four inches of crushed rock. You can then have a rebar structure in a wooden form. That’s another four to six inches thick. Then you’re going to pour your concrete into that perfectly level form, which you will have levelled in advance to get that perfect base or pad.
I’ve gone over that point very quickly but I do have a much more in depth article here that you can read on hot tub pad construction.
Now on top of that pad, you can then build using your blocks. And the block structure is ideal if you’re making a rectangle or a square Hot Tub. If you’re using the hollow CMU blocks, you can drop inside a number three rebar into hollow cavities for added strength. The number three rebar is the 10 millimetres or 0.4 inches thick. You can then fill that cavity with concrete for extra strength.
This method is ideal, whether you’re building an above ground or in-ground block built, hot tub. And that’s something that as DIYer you can actually do, this is actually how I constructed my own hot tub. I founded the buildahottub.com website to share my experience with all of you or the DIY is, and this is the method that I think is the easiest.
It’s especially easy If you’re building a square or rectangular tub. Now, if you’re looking to build something that is cylindrical or has some curves in it you need another method. Maybe a kidney shape or a round pool, then blocks unless you’re a particularly skilled block layer, which I’m not, (I can only put them in a straight line!) you’re going to want to do a poured concrete tub.
Gunite Alternatives – Poured Concrete Hot Tub
What is this? Well, firstly, you still have to build yourself a pad or a base in the same way I’ve already explained above. However, when it comes to creating the walls, you can use wood to create a mould or what is known as a form that you’re then going to fill with concrete. So inside of those walls goes a rebar structure and your plumbing.
Roughly speaking, I’m not structural engineer, but you will have a number three rebar, which is 10 millimetres or 0.4 inches wide. You can put those around a four inch or 10 centimetre centre spacing. That will give you enough strength if you’re not sure, please do check with the structural engineer. If you’re a structural engineer reading this blog, let me know if you agree with my logic here. If I’ve got this wrong, always happy to be corrected.
Once you have that rebar in place, you’ll then add your plumbing to that rebar. You’re going to tie it all in and once you’ve added your plumbing, you add the outer skin. The outer skin is again part of your wooden form and you’re ready to pour that concrete.
Once your moulds are ready, you then pour the concrete into your wooden forms. Once cured, this then creates the walls for your hot tub. I recognise that I have gone over these two methods very quickly.
On my YouTube Channel I have videos that cover both these processes in much more detail.
Of course, please remember that if I can help you in any way, please do get in touch. Whether you need plans, you can get these in my online shop. If you need parts, I can help you with those too. And if you’re looking for something out of the ordinary, and I’m more than happy to do a custom design for you as well.
Thanks for reading
Happy Hot Tubbin’
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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.
Today, I've helped over 1000 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