What type of Spa Construction methods exist?

Type of Spa Construction

What Type of Spa Construction methods exist?

What type of spa construction methods exist? In short, there are three different types of spa construction. There are two types of spa construction that your average DIYer can do. These are poured concrete and block-built spa construction methods. The third method of spa construction is called Gunite or Shotcrete spa construction. This is only for the processional spa builder.

In this blog post, I will examine all three methods.

What is Gunite spa Construction?

Let’s start with the professional method of Spa Construction, known as Gunite or Shotcrete.

Gunite is an alternative form of concrete which is distributed by a hose at a high velocity. Instead of being poured onsite to form solid ground bases it is sprayed on and the concrete is dry and attaches quickly to the host surface.

According to Wikipedia, Gunite was originally a trademarked name that specifically referred to the dry-mix pneumatic cement application process. In the dry-mix process, the dry sand and cement mixture is blown through a hose using compressed air, with water being injected at the nozzle to hydrate the mixture, immediately before it is discharged onto the receiving surface.

Gunite Trademarked

Gunite was the original term coined by Akeley, trademarked in 1909 and patented in North Carolina. The concrete mixture is applied by pneumatic pressure from a gun, hence “gun”-ite.

The term “Gunite” became the registered trademark of Allentown Equipment, the oldest manufacturer of gunite equipment. Other manufacturers were thus compelled to use other terminology to describe the process such as shotcrete, pneumatic concrete, guncrete, etc.

Gunite as a type of Spa Construction involves the digging of your spa shape and installation of the iron rebar. The rebar framework creates a grid around the perimeter of your spa to reinforce the structure.

You’ll begin to see your vision come to life as your professional spa builder sprays a heavy coating of Gunite around the rebar. The Gunite is then smoothed and left to set.

The major difference as a type of Spa Construction is that this is not something you can do as a DIYer. You need some heavy machinery and a lot of skill to carry out this kind of spa construction technique.

One of the big advantages of Gunite over the other two methods is that you end up with a continuous vessel for your spa water. There are no joins so the structure is perfectly in tact.

What is Shotcrete spa Construction?

Shotcrete is another type of Spa construction. However, it is very similar to the Gunite Process we have just explained. Spas can be constructed with the shotcrete or Gunite process. They usually fall under the same category which is why I am not categorizing them as being two different techniques. That said, there is a difference between the two terms.

The difference between the two terms is when the concrete mixes with the water. Shotcrete always refers to wet concrete that’s already fully mixed before it’s shot out of a hose. Gunite is a dry concrete mix that only mixes with water at the end of the nozzle as it’s being sprayed onto its final surface.

That said, since the term Gunite has been trademarked, Shotcrete has been adopted as a non-trademarked term for the same process. Quite often, the difference in the mixing process with water is ignored.

Is poured concrete a type of Spa Construction?

Absolutely. Poured concrete is a type of Spa construction. This process involves laying a base or a pad of concrete. Then, you would build a wooden form or mould for the walls for your hot tub. Inside these walls you would have a metal rebar structure.

Into the rebar structure you would tie your plumbing before you added the rear form for your mould. When all the bracing is in place for your moulds or forms, because there is a lot of weight to hold back with the concrete, you are ready to pour your walls. If you are mixing the lifts (the layers of concrete) yourself, you may see some decolourisation as it is difficult to get the mix the same each time by hand.

If you are having the concrete delivered and pumped into location, you will get a much more uniform colour of concrete. Often, the concrete company will want to know what PSI or strength of concrete you need. Generally, 4000 PSI is sufficient for Spas and small pools.

After you have allowed your structure to cure (set and dry) which depending on the size can take a few days to a week, you can remove the forms. You will be left with your poured concrete walls and your plumbing will be mostly inside of the walls.

Next, you will need to seal the concrete with a chemical sealant before you apply ground and adhesive for your tiles. Make sure that the grout and adhesive is swimming pool grade otherwise your tiles will lift off over time – which of course you do not want.

Poured concrete types of spa construction are good if you are looking to have shapes that are not square or rectangular.

Type of Spa Construction
Type of Spa Construction

What is a block-built type of Spa Construction?

Block built spa construction is where you use CMU blocks, Cinder or Breeze as they are called around the world, to create the walls and the seating for your hot tub. If you are using hollow CMU blocks, then you would add rebar into the blocks and fill them with concrete for strength. The blocks would of course need to sit on a concrete pad that you would have poured in advance.

You then core holes through the walls so that you can fit the plumbing which remains on the outside of the spa.

The internal walls need to be rendered and sealed and you can then finish the tub with either an epoxy resin paint or a tiled finish.

Type of Spa Construction
Type of Spa Construction

What is the best type of Spa Construction?

I think that one can say with confidence that the best type of Spa Construction really comes down to personal preference and a person’s own DOY skills. I don’t think one method is better than another.

What is the easiest type of Spa Construction?

What one person perceives or finds easy, is not necessarily the same for another person. Therefore, I am going to base my point on my own experience on this one. I found, and still believe today even after seeing many of my customers build poured in place spas, that block-built spas are an easier type of construction. Whilst block laying is most certainly a skill, it is one that can be learnt and does not involve any additional skills such as joinery to build wooden forms.

What is the hardest type of Spa Construction?

The hardest type of Spa Construction, certainly for the DIYer must be Shotcrete or Gunite. These types of Spa Construction require specialist training as well as lots of specialist equipment. They are not accessible methods for the DIYer and can only be undertaken by a professional. For that reason, I am classifying them as the hardest type of Spa Construction.

What type of Spa Construction should I use?

In this blog post, we have looked at the three different types of Spa Construction available. We have seen that only two are really options for the DIYer.

The type of spa construction that you will ultimately choose for your project really depends on a couple of things. Firstly, what shape you plan to make your Spa. If you plan to make a square, rectangle or “L” shape spa, then I would suggest that you opted for the block-built type of spa construction.

If however, you are looking to build a cylindrical spa or even a kidney shape spa, then you should really be looking at using a poured concrete type of spa construction. This method is much more conducive to curved edges which are difficult to do with blocks.

Ultimately, the type of spa construction that you choose will be the one that you feel most comfortable undertaking. For me, this was block built. That said, I have many customers who feel much more comfortable mixing and pouring concrete for construct their spas.

Do you have any questions about the types of spa construction? Can I help you with your project?

If so, please get in touch below. I am more than happy to answer any questions that you have and I am sure I can help you with that dream spa.

Happy Hot Tubbin’

Can I Help You?

If I can help you in any way I would love to hear from you. You can get in touch using the form below.

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

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