How a Hot tub Is Built Overview

Video featuring Hot Spring Spas

Hot tubs are generally built in the following steps. Each manufacturer will have slightly different orders and some have additional steps that are unique to their spa models.

Step #1
Building the Shell of the Spa

What is a Hot Tub shell Made of?

An hot tub shell is made from a single sheet of acrylic material. The acrylic is heated until it almost melts. It will visibly sag in the middle.

It is then placed over a mold for the specific spa model being built. Each spa model will have a different mold. Powerful vacuums help suck out any air trapped between the mold and the acrylic sheet, pulling the acrylic to the mold.

This results in a smooth and perfectly formed shell. After the acrylic shell has cooled and hardened (which takes about 3 minutes after being vacuum formed), it’s reinforced with a combination of resin and fiberglass to give it additional strength and waterproofing.

Some acrylic shells are formed through a variant process where a layer of the polymer acrylonitrile butadiene styrene, also known as ABS, is pre-applied to the acrylic sheet before going into the mold. The resulting hot tub shell is durable, energy efficient, and aesthetically pleasing.

If you own an acrylic hot tub, it will withstand normal wear and tear for many years without showing signs of damage. Acrylic hot tubs are produced in a variety of stunning colors and patterns.

Also, acrylic hot tubs retain their heat very well when insulated with a high-quality material.

Acrylic tubs are more expensive than vinyl or plastic tubs. However, their ability to hold in heat translates to better energy efficiency than other hot tubs. This results in a lower electricity bill needed to keep your water hot and relaxing.

While hot tub shells made of other materials have some advantages, hot tubs with acrylic shells are the ideal choice, for those who value quality, performance, and appearance.

To learn about other hot tub shell types check out this page from hot spring spas.

Steps in making a spa’s shell

  1. Acrylic sheet cleaning
  1. Cleaning of the vacuum mold

Cleaning the Acrylic Sheet
Cleaning the Vacuum Mold

Cleaning the acrylic sheet

Cleaning the mold

  1. Heating the acrylic sheet

Acrylic Heater
Heated Acrylic Sheet

Heater Panels

Heated Acrylic Sheet

  1. Vacuum forming the shell

Vacuum Forming Acrylic Hot Tub Shell

Small scale example of Vacuum Forming

Hot Tub Vacuum Forming (Ft. Master Spas)

  1. Reinforcing the shell – AKA Lamination
  1. Cutting holes for jets and electronics

Cutting Jet holes in a spas shell

Step #2
Adding the spa’s frame, plumbing, insulation, & electronics

  1. Adding plumbing, pumps, & Insulation

Installing the spas plumbing

  1. Adding Electronics, Heaters, & Controls

Installing the main board
Hot Tub_Spa_App_WiFi_Topside Panel
Hot Tub_Speaker

Step #3
Closing up the Spa & Final Testing

  1. Installing the cabinet panels (Skirting)

  1. Final inspections and testing

The final inspection is an important phase of building a spa as it checks to make sure there are no leaks, deformities, electrical issues, etc. before being drained and shipped out of the factory to later end up at your home. If any issues are found they are repaired and the spa is retested until it is fully ready to be enjoyed in your back yard.

Final Testing of a spa