How to Make a Fiberglass Bathtub: Procedure + Care

A fiberglass bathtub is designed and built using the same principles as any other fiberglass structure. However, you must first create a mold and then gradually construct the fiberglass object until complete.

Make a fiberglass bathtub by planning where to place the tub and its size. After that, create a tub frame, cut off excess materials, add fiberglass cloth and resin to the desired thickness, then let it dry. Detach the cured tub, fix the faucets then paint it before letting it dry.

The procedure is time-consuming and contains dangerous substances that must be handled with caution. It isn’t, however, very different from making a resin bathtub. This article will take you through how to best make your fiberglass.

Fiberglass Tub On Mold

How to make a fiberglass bathtub

For this procedure, you will need the following materials; paper and pencil, measuring tape, rulers, arc gauges, framing material of wood or PVC, nails or PVC glue, hammer, foam, mold, cutting tools, acetone, sponge, gloves, mask, fiberglass sheets, resin, paint roller, paint tray, air roller, flat prying bar, sander, drill, cutting bore bits, and water-resistant caulk.

Follow these steps:

Step 1: Plan ahead

Examine the room where the new bathtub will be installed once completed. Design and plan the size of the bathtub you wish to create with pencil and paper. Pay attention to the ideal arc size and angles. 

With rulers, measuring tapes, and arc measurement gauges, determine these measurements and add them to your design on paper.

Step 2: Create a tub frame

Create a tub frame using the dimensions from your design. To construct the sizing skeleton of the mold, use wood, and PVC pipe joined with PVC glue or a hammer and nails. Next, take the foam mold and place the components into the frame to make the mold’s body. 

Cutting instruments like razors and knives can be used to cut the foam. To make the mold’s inner surface, shape the foam. Match the form to the measurements of your tub, adding and removing foam as needed to achieve the desired mold shape.

Step 3: Cut off excess materials

Cut off necessary sheets of fiberglass fabric with scissors so you may handle them when constructing the tub. Using acetone and a sponge, clean the inside mold surface wall. Protect your hands by wearing gloves. 

To extract the final mold from the tub afterward, spray it with a nonstick wax treatment. Buff it out as needed to remove the wax from the inside surface.

Step 4: Add fiberglass cloth and resin

Pour fiberglass resin into a paint tray after mixing it. After immersing the mold in the tray, use a tiny painting roller to apply the resin to the interior of the mold. After the initial resin layer has been applied, lay down a fiberglass cloth sheet. Flatten the fabric into the resin with an air roller. 

Cover the surface with cloth sheets and continue until the first layer is complete. More resin should be applied to all of the initial sheets. Allow a few minutes for the layer to dry before repeating the process for at least two or three additional layers. Allow an hour for the first phase to dry within the mold.

Step 5: Add more fiberglass cloth and resin

Apply more layers of cloth and resin until the tub’s surface is coated with the necessary thickness of fiberglass resin and cloth. Ensure that the thickness is at least 20 millimeters. 

To avoid air bubbles, smooth each layer as it is applied. Let the final layering dry and cure while you clean up the excess glue, tools, and extra cloth.

Step 6: Detach the cured tub

Two days later, detach the cured fiberglass tub. Using a separation tool like a flat prying bar, separate the tub from the foam. Remove the tub shell and put it in a convenient location. Sand the edges and the surface to smooth them out in every area. As needed, remove any sharp edges.

Step 7: Fix the faucets

Determine the position of the tub hardware holes and the drain. Then, using a drill and boring bit sized to the plumbing equipment put in the tub, cut these cavities and voids. 

When done, sand the edges of the holes to make them neat cuts. After that, coat it with thick epoxy paint and surface finishes. To get a clean finish, apply additional coats.

Step 8: Let it dry

Allow the painted tub to dry. Place the fiberglass tub in the bathroom after you’ve finished building the surrounding tub frame and countertops. 

To ensure no tub leaks, connect the plumbing hardware and test the system. Next, use a water-resistant sealant caulk to seal the tub’s final outside edges to the surrounding counter-frame.

When constructing the fiberglass tub, take your time. Do not hasten the process. Instead, gently apply each layer of fiberglass to produce a smooth, thick surface. When you’re done, you’ll be pleased with the results.

Some of these steps can be used with other types of tubs such as when making a wooden bathtub as well.

Advantages of a fiberglass bathtub

Below are some of the advantages of owning a fiberglass bathtub:

Advantages Disadvantages
Affordable High long-run expenses 
Easy to repairInconsistent surface

1. Affordable

For most families, the most essential advantage of fiberglass is its affordability. The material is cost-effective, costing less than natural materials and other plastics such as acrylic. 

When it comes to bathroom modifications or redesign, the fixtures and components that pack the most design punch, including shower tiling, vanities, and flooring, should be prioritized above the bathtub.

2. Easy to repair

It’s a significant advantage to repair your fiberglass tub since it’s always less expensive to fix than to replace. As a result, you save delivery costs and the extra installation time for buying a new bathtub.

3. Lightweight

Because fiberglass tubs are lightweight, they are easier to install in your house. Other materials result in a big tub that is difficult to transport and position correctly. 

Another essential aspect of the material’s light weight is that it eliminates the need for additional floor support to sustain the tub’s weight. This will save you a lot of costs and time.

Disadvantages of a fiberglass bathtub

Some of the downsides of having a fiberglass tub include the following:

1. High long-run expenses

Fiberglass tubs exhibit more wear and tear than tubs made of porcelain or ceramic. In addition, because the surface is somewhat fragile, it is prone to fractures and scratches. This will mean you’ll be incurring a lot of maintenance costs.

2. Inconsistent surface

These devices aren’t meant to be used for a long time. While the gel coating covers the unit’s surface, the substance beneath the covering is porous. As a result, as the layer begins to peel off in spots over time, water can leak in and cause harm to the tub and even the floor below it.

Fiberglass bathtub repair and maintenance

Some tips to keep your fiberglass tub clean include the following:

  • When it comes to extending the life of your tub, like with other home fixtures, prevention is the best approach. Regular cleaning with the correct cleaner and procedures is your first line of protection. 
  • Mild soap, such as dish soap or even baking soda and water mixture, work well on this substance. This is the case because the covering is thin and vulnerable to wear over time. 
  • For the same reason, abrasive cleaners should never be used on these fixtures.
  • Finally, avoid waxing products on this floor since they might be dangerous while the shower is on.

With these tips, your tub will remain in good working condition for a long time.


While designing and crafting a fiberglass bathtub may seem hectic, it is not impossible. I hope that with the above information, you can make your tub and be able also to maintain it. 

Frequently Asked Questions

How does one make a fiberglass bathtub?

Fiberglass-reinforced plastic is made by heating together small interwoven layers of glass. These are then molded, shaped, then sprayed with a resin gel coat to form a bathtub. It’s affordable and easy to install.

Can you make your own bathtub?

You can build your own bathtub from several materials such as tile, wood, resin, and stone.

What are the layers of a fiberglass bathtub?

A fiberglass bathtub is made of layers of surface coat, polyester resin, and fiberglass reinforcement.


California Polytechnic State University. Bathroom Remodel for Son Care Foundation, Inc.

America Bathtub. Know When You Need To Advance from a Bathtub Repair Kit to a Fiberglass Inlay Repair.

NC State University. Curbless Showers.

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