How to Tell if My Shower Is Fiberglass or Acrylic

There are a handful of different materials used for the walls and based of a shower. Acrylic and fiberglass are two reasonably common materials. In this article, I will provide a complete rundown of how to tell if your shower is made of fiberglass or acrylic.

As a general rule, acrylic will be slightly bendy whereas fiberglass is completely rigid and will not bend at all. If you can observe the underside of the shower, a fiberglass shower pan can have fibers and a rough finish. But, this is not always the case. 

There are a few different methods to determine if a shower is made of fiberglass or acrylic. Below, I will explain these methods in detail so that you can tell for sure whether your shower is fiberglass or acrylic.

Methods To Tell if a Shower Is Fiberglass or Acrylic

The easiest method is to apply a small amount of weight to the area of the shower you’re testing such as the walls or the shower pan. Or, to knock on it. Fiberglass is very rigid and behaves like solid wood when knocked on or pressed. 

It won’t give or bend at all if you apply pressure to it. And it will produce a muted sound, similar to when knocking on drywall – which are what most walls in a home are made of.

Acrylic, on the other hand, will bend slightly, and feel softer and more plastic by comparison. If you stand on an acrylic shower pan, it will have a bit of bounce to it. When you knock on it, it will have a soft plastic feel and a soft dull sound. 

Seeing what the unfinished side looks like – where possible

Another good test where possible is to look at an unfinished side. This isn’t possible for shower walls but does work for a shower pan if it hasn’t yet been installed. Or, if there is a crawlspace or something similar underneath the shower where you can shine a flashlight on the underside of the shower pan.

As you may know, fiberglass is made with lots of tiny fibers that are stuck together using a special type of glue-like mixture. The top side is finished to make it perfectly smooth. But, the underside can sometimes be left unfinished. 

You will be able to see individual fibers, which you may have seen before. Here’s a video that shows the different types of fibers used to make fiberglass, so you can see what it will look like if the underside of your shower base is not finished. 

Acrylic shower bases by comparison have a completely smooth underside. Or, will have the appearance of rough plastic rather than fibers.

However, this is not a 100% foolproof test because some fiberglass shower bases are finished on the underside, and won’t have visible fibers.

Testing the weight of a shower base is reliable but not always practical

The last method to tell the difference is the weight of the shower base. This test can’t be performed if the shower base is already installed, and only if you are doing a remodel and removing your existing shower. 

Or, if you’ve purchased a shower base and didn’t ask or forgot what it’s made of. Because you will need to remove it from the grout and/or sealer that is holding it in place to be able to test its weight. An acrylic or fiberglass shower base is typically around 1.5 cubic feet of material.

This is calculated as a 3-foot by 3-foot shower pan. That is typically around 2 inches thick on average. Which = 3 times 3 times 0.166 = 1.54 cubic feet.

  • Fiberglass weighs on average: 120 lbs (54 kg) per cubic foot (source)
  • Acrylic weighs on average: 60 pounds (27 kg) per cubic foot (source)

Therefore, a fiberglass shower bass will weigh around 180 lbs (76 kg), and an acrylic shower base will weigh about 90 pounds (40 kg). This can be measured with a scale but can be quite difficult. Typically, if you feel the weight of it you can tell. 

A fiberglass shower base will need about 2 average-strength people to lift it. Whereas, an acrylic shower base can only be lifted with a bit of effort by one average strength person. Also, if you know someone who weighs around 180 lbs, you can try lifting them up to get a reference for how heavy a fiberglass shower pan is.

Can Fiberglass and Acrylic Showers Be Cleaned the Same

Acrylic and fiberglass have different compositions and therefore care needs to be taken when cleaning them not to damage them. 

Some cleaners react chemically with different materials. So, here’s the lowdown on whether a fiberglass shower and an acrylic shower can be cleaned with the same cleaners and in the same way.

As a general rule, fiberglass and acrylic showers can be cleaned the same way. Except, that you should not use bleach on a fiberglass shower. The cleaners not to use on fiberglass and acrylic showers are harsh chemicals and solvents like rubbing alcohol.

Harsh chemicals will degrade the surface of acrylic or fiberglass and cause them to show discoloration and can roughen their smooth finish.

Which Is Heavier Fiberglass or Acrylic

Fiberglass and acrylic are common materials used for all sorts of different things. Fiberglass is significantly stronger than acrylic but the extra strength it provides isn’t always needed. But, here’s which is heavier, fiberglass or acrylic.

On average, fiberglass is twice as heavy as acrylic. 1 cubic foot of fiberglass weighs about 120 lbs (54 kg), whereas 1 cubic foot of acrylic weighs 60 pounds (27 kg). Fiberglass is also more rigid than acrylic. Acrylic will bend slightly when pressure is applied to it, whereas fiberglass won’t.

Fiberglass shower pans and acrylic shower pans last around the same amount of time – 10 to 20 years. But, acrylic shower bases are easier to install because they are lighter. Acrylic shower pans are also more comfortable than fiberglass shower pans because they are a little bit flexible.

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