How to Make a Fiberglass Bathtub

Do you want to make your own fiberglass bathtub? You might not know what you need for this project, but don’t worry! This blog post will show the necessary steps in how to make a fiberglass bathtub. The materials are inexpensive, and it is an easy process that anyone can do at home.

How to Make a Fiberglass Bathtub

Fiberglass is a composite material made of woven glass fibers. It has been used in the construction industry for decades, and it can be formed into just about any shape. So stop reading this paragraph and get started on making your next DIY project happen!

Required Tools and Materials

  1. Respirator
  2. Safety Glasses
  3. Wet Sandpaper (220 grit)
  4. Fiberglass Cloth (choose a weave that is suitable for your project)
  5. Polyester Resin (regular or high performance)
  6. Catalytic Hardener (for high-performance resin only)
  7. Mixing Cups
  8. Stir Sticks
  9. Plastic Gloves
  10. Bucket

A Detailed Guide How to Make a Fiberglass Bathtub

A fiberglass bathtub is a great option if you’re looking for a durable and affordable tub. Fiberglass is a rigid, weather-resistant material that will last for many years with proper care. Here’s how to make your own fiberglass bathtub:

Step 1: Measure Dimension

The first step in How to Make a Fiberglass Bathtub is to measure the dimensions of your bathtub. This will help you determine how much fiberglass resin and cloth you’ll need. How big of a fiberglass “blanket” depends on factors, including the density of the weave, but generally, 1 yard can cover about 30 square feet.

Measure the Bathtub Dimension

Step 2: Prepare Your Work Area

To ensure a successful Fiberglass Bathtub project, keep your work area clean of any debris that could get into the fiberglass resin. Small pieces can become embedded in the finished product, while larger pieces could scratch or damage it. Cover your workspace with newspaper, and protect your eyes with safety glasses. Cover your mouth with a respirator or dust mask, and wear gloves to protect yourself further.

Step 3: Mix the Resin

The resin you use for Making a Fiberglass Bathtub should be catalyzed with a hardener. Follow the manufacturer’s instructions for how to mix the two products. Be sure to measure accurately, as improper mixing can cause problems with the finished product. Before you start, you will need to create a mold for your fiberglass bathtub. You can use a shower pan liner or an inflatable pool as a base for your mold. Make sure the bottom of the mold is completely flat and level.

Step 4: Wet the Surface

The fiberglass resin needs water to help it stick to the bathtub. You can either use a spray bottle or a paintbrush to wet the surface. It’s a good idea to wet one square foot at a time and use a wire brush to get rid of any dirt or debris that might stop the resin from sticking.

Wet the Bathtub Surface

Step 5: Apply Resin

After wetting the surface, apply the mixed resin evenly with a paintbrush. This will create square edges and make it easier to achieve the desired thickness. Add one layer of fiberglass cloth at a time, allowing each layer to dry before adding the next, until you reach the desired thickness.

Step 6: Lay the Cloth

Once the resin has hardened (which should only take a few minutes), you can lay the fiberglass cloth over it. Be sure to work quickly, as the resin will continue to harden. You may need to use weights or clamps to keep the cloth in place while it dries. How long to let it dry will vary depending on your project and conditions, but generally, you should let the resin begin to harden before moving on to the next step.

Step 7: Repeat

After the first layer of resin dries, apply another layer over the fiberglass cloth. Wet the surface, add the resin, and then add another layer of material. Let it all dry before sanding. For the best results, Fiberglass Bathtub recommends using 220-grit sandpaper.

Step 8: Apply Sealant

A fiberglass bathtub is not waterproof, so you’ll need to apply a sealant to protect it from moisture. Using polyurethane sealant is recommended for making Make a Fiberglass Bathtub. Follow the manufacturer’s instructions for application. After the sealant has dried, apply a layer of caulk around the perimeter of the tub to prevent leaks.

Step 8: Finish the Surface

Once the resin has fully cured, you can sand down the surface to achieve a smooth finish. Be sure to use wet sandpaper (220 grit), and work in a circular motion. For a Fiberglass Bathtub, using a bucket of water to keep the sandpaper wet is recommended. Finally, apply a coat of automotive clear coat to protect your new fiberglass bathtub from scratches and fading. Use paint sprayers or an airbrush to apply a clear coat.

Using Sandpaper on Bathtub

Tips and Warnings


  1. Tape off the areas you don’t want fiberglass to go, such as the floor and countertop.
  2. Apply a layer of fiberglass cloth to the surface and then soak it in resin.
  3. Wait for the resin to dry and apply a second layer.
  4. Let the fiberglass bathtub dry entirely before using it.


Be very careful when working with fiberglass. It is a sensitive material and can easily cut your skin. Always wear gloves and safety glasses when working with it. If you get cut, rinse the wound with soap and water and apply hydrogen peroxide. Seek medical attention if the cut is severe. Working with fiberglass can be a messy job. Have a wet towel on hand to clean up any spills.

You Can Check It Out to Get Suction Cups to Stick to Bathtub

How Many Layers of Fiberglass Do I Need for a Tub?

To ensure that the tub is sturdy and durable, you should add a few more layers of fiberglass than you think is necessary. This gives it a “built-in” strength that will help to prevent cracking when the tub is filled with water.

How many layers you need really depends on what kind of fiberglass resin you use (regular or extra-thick), the size of your mold (larger sizes require greater thicknesses), and how much weight you plan to put into your finished tub. For average-sized bathtubs, figure on four to five layers of fiberglass cloth.

How Can I Use a Fiberglass Bathtub Without It Cracking?

A fiberglass bathtub can last for up to 50 years if it is properly taken care of and well-maintained. However, the actual lifespan of your tub will depend on several factors, such as the quality of materials used, whether it has been damaged over time, where you live, and who uses the tub.

Fiberglass Bathtub Can Last Many Year

Porous areas like whirlpools or jets that have been worn down from use will start to allow water into the fiberglass, which can cause cracking later on—to prevent this from happening, make sure you check these areas regularly for wear and replace them as needed.


Following the steps on how to make a fiberglass bathtub, With the right tools and materials, you can make your fiberglass bathtub in no time. If this sounds like something you want to try, let us know! We’re happy to help answer any questions or provide detailed instructions on how to get started. You may also be interested in reading our other blog posts about DIY projects for a bathroom remodel. Thanks for reading – we hope it helps!

You can also check it out: How to Make Bathtub Non Slippery

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