Acrylic vs Plastic Rotomould Spa Pools 2024 (Considerations, pros, cons and more)

The shell material on the inside of your spa is the most crucial component of a spa pool. So you want to make sure it’s built to last. Acrylic and plastic rotomoulded spa shells are the most common. Which is best? Read this article to find out.

Acrylic vs Plastic Rotomould Spa Pools hero

There are a lot of things to consider when buying a spa pool. One of the most important choices you’ll have to make is the type of shell to pick. This article will discuss the top two choices for spa pool shells – acrylic and rotomoulded. We will go through the advantages and disadvantages of these two options and give a final recommendation.

This article mentions brand names not affiliated with Spa World™ or Vortex Leisure Pty Ltd. You can see the list of the brand owners at the bottom of this article.

What is the spa shell?

The spa shell is the surface where you sit in a spa pool. It holds the water and is the part you see and use the most.

In some ways, the shell is the most important component of a spa pool. Other spa parts can be replaced, but not the spa shell. You’re stuck with the shell that came with your spa – so it pays to choose a good one!

Because the shell carries the load of the water and spa users, it has to be durable. It should also be well-designed because it is a large part of the overall appearance of the spa and what people sit in, see and feel when using it.

What are spa pool shells made of?

The hot tubs that were the precursor of current spa pools were made from wood, concrete or tiles.

Today, most spa pools have shells that are made from acrylic or rotomoulded plastic, similar to what plastic kayaks are made from.

The material of the spa shell is critical because it affects the spa pool's pricing and lifespan. It also plays a role in the overall appearance and comfort of the spa pool.

What to look for in a spa pool shell?

There are several things to consider when looking for the best spa shell. In many cases, the shell is the deciding factor for spa buyers, not the brand – although that is important too for other reasons. Click the button below to learn more about this, including what to look for in a spa pool.

Here are the main things to look for in a spa shell:

  • Material: The two most popular materials for spa shells are acrylic and rotomould. See the pros and cons below.
  • Appearance. The appearance of the shell is also important. It can be glossy, matte or textured - depending on your preference.
  • Touch. Ideally, the shell surface should be smooth to touch and comfortable to sit on.
  • Insulation. How well the shell can retain heat is another important consideration. The spa shell is not the only component that contributes to heat retention, that’s the central role of the insulation, but it does make a difference.
  • Colour. Spa shells come in a variety of colours.
  • Durability. Make sure the spa shell is made of a strong material like Continuous Cast Acrylic, that can withstand years of use, and is resistant to fading, stains, cracking or blistering.
  • Warranty. As a minimum, look for a 10-year structural warranty and a 5-year acrylic surface warranty.

What is an acrylic spa?

An acrylic spa has a shell that’s made from a single piece of acrylic sheet that has been heated and placed over a mould. A vacuum is then used to remove all the air in between the mould and the acrylic material, resulting in a smooth finish.

Acrylonitrile butadiene styrene (ABS) backed acrylic is heated, allowed to cool and reinforced with fibreglass and resin. In higher quality spas, a ceramic powder is added for extra rigidity and durability. Without this last step, supports are required to keep the shell from sagging.

Pro Tip: We recommend looking for a different model if you see wood supports propping up the spa seats.

Spa shell

Acrylic Spa Shell

What to look for in an acrylic shell spa pool

One of the main things to look for in an acrylic shell for a spa pool is the amount of resin used in its manufacture.

You don’t need to carry out extensive calculations to do this. Just try checking the shell. If it appears thin or flimsy, ask for more details and specifications of how and where it was made.

Look for an acrylic shell that’s oven-cured. This process will ensure that the acrylic layer and the fibreglass backing stick together.

Ask the salesperson if the spa pool they’re selling has an oven-cured shell or if ceramic powder was added to the shell during manufacturing. If they cannot give you a simple yes or no answer, you may want to consider shopping elsewhere.

Watch: Vortex® Spas 4-Layer Acrylic Spa Shell

Are acrylic spa pools any good?

Acrylic is considered the far superior material for spa shells – which is why the leading spa brands use acrylic shells.

High-quality acrylic is durable, energy-efficient, and looks great. It also retains heat well when insulated with quality materials like high-density foam.

Spas with acrylic shells are usually more expensive than those with plastic or vinyl shells but they generally have a better finish.

You’ll find that many of the top brands use acrylic shells in their spas, including HotSpring®, Jacuzzi® Spas and Vortex Spas®.

Not all acrylic spas are made equal, however. The acrylic sheets made in the United States are considered to be the best for use in spa shells. As an indicator of quality, make sure to check the acrylic used on a spa shell is from the United States.

The way that the acrylic shells are made also has an impact on the quality of the shell. The fibreglass backing must have a vinyl resin that will fuse with the back of the acrylic shell. Without that, the shell will delaminate over time, losing its smoothness and aesthetic value, and will possibly leak.

High quality acrylic spa shells should also be oven-cured to prevent delamination. This is something you should ask the salesperson.

Jacuzzi j275 spa top view

Jacuzzi® J-275™ Spa shell

Pros and cons of acrylic spa pools

Pros of acrylic spas:

  • Acrylic shells are durable
  • Retain heat well (when properly insulated)
  • Have a higher-end appearance compared to rotomoulded plastic since they can retain a shiny appearance.

Cons of acrylic spas:

  • Acrylic shells will only retain heat if they have adequate insulation. Without that, they are just as energy-efficient as rotomoulded plastic with the same level of insulation.
  • Spas with acrylic shells are heavier, making it harder to move them around.

What is a rotomoulded spa?

Rotomoulded spa shells are made from plastic. The process involves heating plastic powder, applying it to a mould, and rotating it to ensure the entire mould surface is covered. For the most part, rotomoulded spas are more affordable than acrylic, although that still depends on the brand and model.

What to look for in a rotomoulded spa shell

Look for a rotomoulded spa shell that has a good aesthetic. Depending on your tastes, you may find the typically matte finish of a rotomoulded shell a bit dull compared with the glossy style of acrylic spas. Other options include synthetic wooden panels.

As with any other shell type, you’ll also want to consider the insulation around the shell as it determines whether the spa can retain heat or not and can affect the overall running costs. Essentially, the better the insulation, the cheaper the spa will be to run.

Are rotomoulded spa pools any good?

Rotomoulded spas are generally cheaper than acrylic spas making them a good option for people on a budget or if you’re looking for a starter or entry-level spa.

Be aware that while the upfront cost of a spa is not the only factor to consider. You should also look at the ongoing running costs of the spa.

For example, while acrylic spas are typically cheaper to buy than acrylic options, the ongoing running costs are generally higher and they may not last as long as better quality acrylic alternatives.

For these reasons it may be worth spending a bit more upfront on a higher quality spa with lower running costs, that’s built to last.

Pros and cons of rotomoulded spa pools

While rotomoulded spa shells are generally considered lower quality than acrylic alternatives, they do have their advantages – as we explain below.

Pros of rotomoulded spas:

  • Affordable. Compared to acrylic, rotomoulded spas are more affordable. The price range of rotomoulded spas is from $3,000 to $8,000, while acrylic spa prices can start at $7,000. It’s not surprising that many first-time spa buyers are interested in rotomoulded spas.
  • Lightweight. Rotomoulded shells are also lighter, so spa pools with rotomoulded shells can be moved around more easily than acrylic spas.
  • No risk of shell blistering. Blistering happens when water gets under the acrylic sheet of a shell that hasn’t been cured properly, although this is primarily a problem with acrylic shells that have been poorly manufactured due to cost-cutting. You will not have that problem with a rotomoulded shell.

Cons of rotomoulded spas:

  • Dull finish. The dull matte finish of a rotomoulded spa shell can be unattractive to some users.
  • Plastic touch feeling. The plastic touch feeling of a rotomoulded shell is considered to be on the lower end.
  • Inability to retain heat efficiently. This is the case when the shell has inadequate insulation although this issue is not exclusive to rotomoulded shells.

In Summary

So, which one is better, between acrylic and rotomoulded spa shells?

Spa experts generally agree that acrylic spa pool shells are better than rotomoulded ones. They look better because of their finish and they last longer.

While acrylic spas have a few disadvantages, as explained above, they are far outweighed by the benefits they offer. If you have the budget, we highly recommend opting for a spa pool with an acrylic shell.

Keep in mind that the other components of the spa pool can be replaced, but you cannot replace the shell. That’s why you need to pick the right one. Visit the Spa World™ spa pool product pages to get more details about spa pools.

Download our Ultimate Spa Buyers Guide if you want a spa pool.

DISCLAIMER The following registered trademarks are owned by companies not affiliated in any way with Spa World™ or Vortex Leisure Pty Ltd – the parent company of Spa World Ltd: *HotSpring® Spas is owned by Watkins Manufacturing Corporation (Watkins).

Affiliations: Vortex® Spas and Spa World® are trademarks owned by Vortex Leisure Pty Ltd. The Jacuzzi® brand is owned by Jacuzzi Inc. and exclusively licensed for use to Spa World™ in Australia and New Zealand.

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