Spa Shell

Foam Filled
Non-Foam Filled

Control Panel

Suction Side
Pressure Side


Stress Relief

Spa Cover
ASTM Standards

Top 10 Questions


Spa Shell

One of the most critical elements of a spa or hot tub is the actual shell. The biggest problem in spa construction is gespa shelltting a strong shell that doesn't crack, split, blister, discolor, or delaminate. Unfortunately, over many years, a spa shell will show some minor cracks. Depending on the type of shell, this natural wear and tear can easily be repaired.

A majority of manufacturers use one of two different methods to construct their spa shells:


1. Co-Extruded Materials.

This plastic is made up of acrylic and ABS bonded together. The ABS is a softer plastic that has trouble bonding with other plastics, and does very little to add structure to the spa. This material also expands and contracts faster than the acrylic. These two traits can lead the spa owner to problems down the road. When the spa is exposed to sunlight or a high temperature difference, such as filling the spa in cold weather, surface cracks can develop. Also, due to the slipperiness of the ABS there is a tendency for the acrylic to delaminate, or blister, over time. You can usually tell a spa that is made from these materials by the surface warranty that they will provide. If it is shorter than ten years they usually are made of a co-extruded material.

Once this plastic is formed into the shape of the spa, it is then coated with a layer of high density foam. This is what gives the spa shell its structure. These spas typically require full foam. Without it, the spa is unable to support the weight of the water. These types of plastics and/or manufacturing processes result in an inferior product due to the weakness of the spa shell itself, and the high possibility of delamination. If you want to be a smart buyer, we believe you should stay away from foam filled, non-fiberglass spa shells.

It is important to remember that the one element of a spa that can't be replaced is the shell. If it breaks, you will definitely be without a spa.

2. Using a sheet of acrylic to mold the shape of your spa.

Since acrylic is not a strong plastic, structurally speaking, it should always be reinforced with fiberglass. When we say reinforced, we mean the acrylic mold should be backed with at least 3 layers of hand -rolled fiberglass. This is sufficient enough to support the weight of the water over a long period of time. This will not only give your spa the support it needs to hold the weight of the water, but it also allows your spa to maintain its structural integrity for many years to come. Unfortunately, some manufacturers take the easy way out to cut costs, and only back their acrylic molds with one or two layers of fiberglass.

Spa Shell



An acrylic shell lined with 3 layers of hand rolled
fiberglass creates the strongest spa shell available.




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