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Fiberglass Pool Repair Tips

Fiberglass Pool Repair

Fiberglass swimming pools have a distinct advantage over concrete pools. Although they might seem less sturdy than concrete, fiberglass pools are actually durable and easy to maintain. They are also more economical to upkeep, as they need fewer chemicals and less scrubbing. However, it’s important to note that fiberglass pools can sometimes develop cracks or bulges. Here’s what you should know about fiberglass pool repair.

What Is a Fiberglass Pool?

Fiberglass pools are made from large, molded fiberglass structures that are coated with a gel to make them non-porous. You can choose from a variety of shapes and sizes to fit the space you have available. Typically, the pool structure is installed in the ground, and concrete is used to secure the pool in position.


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How Can You Tell If Your Fiberglass Pool Needs to Be Repaired?

Over time, hairline cracks, also known as spider cracks, can develop in the gel coat of a fiberglass pool. These tiny cracks aren’t harmful, but they can spoil the look of your pool. As the pool gets older, you might see larger cracks. If you notice damage that is wider than 1/8 inch and longer than a foot, there may be a problem with the foundation. In this situation, you will need to call a professional pool repair company.

Why is Fiberglass Pool Repair Important?

If you ignore minor cracks, they will grow and eventually become more expensive to fix. Water can leak from larger cracks. If these cracks are at the bottom, water can seep under the fiberglass shell. This can erode the foundation and lead to costly repairs.

Tools and Materials Required for Repairs

For fiberglass pool repairs, you will need some basic tools. A fiberglass repair kit is essential, along with an electric disk sander, putty knives, a clean cloth, acetone, and masking tape. You will also need a ribbed roller, a paint roller, and a sanding roller. It’s best to purchase a swimming pool repair kit from a pool supply store. This ensures that the items are compatible and won’t be damaged by the pool chemicals you use.

Six Tips for Fiberglass Pool Repair

Drain the Pool

First, drain the pool and let it dry completely. This lets you inspect the damaged areas more clearly. While it’s possible to make repairs underwater, it’s not recommended because the repair might not last if the area isn’t fully dry.

Sand the Damaged Area

Use an electric sander to sand down the area around the crack. This helps remove all loose paint and debris. After sanding, clean off the residue with acetone and a clean, dry cloth. Manual sanding won’t achieve a smooth finish.

Mark and Cut Out the Area

Remove the sanding disc from your sander and replace it with a diamond-edged cutting wheel. Use a permanent marker to outline a 2-inch area around the crack. Cut out the marked area along the lines.


Apply the putty to the crack using the bond coat from your repair kit. Mix it according to the kit’s instructions. Fill in the space you created, making sure it’s level and smooth with the pool’s surface. Wait for it to set.

Apply the Putty

Apply the epoxy putty over the bond coat using a putty knife. Follow the instructions in the pool repair kit. Allow it to dry completely, then sand the area and clean any debris with acetone.

Apply Gel Coat and Fiberglass Cloth

Use a paint roller to apply a gel coat to the masked-off area. While the gel coat is still wet, place the fiberglass cloth on the surface and roll it with a ribbed paint roller to remove air bubbles. After the gel coat has dried, sand the area and remove dust with acetone. Allow the sealant to dry for two to three days before refilling the pool with water.

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How to Repair a Hole or Crack In Your Fiberglass Swimming Pool

Required Tools List:

  • Electric disk sander
  • Fiberglass Repair Kit (Automotive kits can also be used)
  • Diamond-edged Cutting Wheel

Step 1: Drain the Pool and Inspect the Extent of Damage

To fix a cracked or bulging fiberglass pool, you must first drain it and let the water evaporate. This helps you see the entire damaged area clearly and prevents moisture from interfering with the repair process.

Although draining the pool takes time, underwater repairs are not recommended. They can prolong the repair time and cause cracks to reappear because the area hasn’t dried properly.

Once the pool is dry and clean, it will be much easier to assess the extent of the damage. The approach to repairing smaller cracks differs from fixing larger splits.

Step 2: Sand the Damaged Area

To remove dust and loose paint, use an electric sander. Manually sanding the area will not produce as smooth a result as an electric sander can.

Mark a 2-inch area around the damaged spot using a marker. Then, replace the sanding disk with a diamond-edged cut-off wheel and cut out the marked area to the depth of the crack.

Step 3: Apply the Bond Coat

Then, mix the bond coat according to the instructions included in the repair kit. Use a putty knife to fill in the gap, making sure it’s level with the pool surface. Wait for it to dry until it becomes tacky.

If the crack is leaking water, apply hydraulic cement before the bond coat to seal it effectively.

Step 4: Apply the Polyester Putty

First, catalyze the polyester putty to start a chemical reaction. You’ll need to use an epoxy, which should be included in your repair kit, to do this. The more catalyst you use, the faster the putty will cure and the harder it will become. Use a scraper or putty blade to smooth it out. After it has dried, smooth the surface with an electric sander and then wipe it down to remove any dust.

Step 5: Apply the Gel Coat & Fiberglass Cloth

  1. Use a roller to apply the gel coat, or an air sprayer for a more even coat.
  2. While the gel coat is still wet, apply the fiberglass cloth.
  3. Use a ribbed rolling pin to smooth out any air bubbles or folds.
  4. Ensure the fiberglass cloth covers the entire 2-inch perimeter of the repair area.
  5. Apply another layer of gel coat and let it dry.
  6. Once dry, sand it smooth and wipe off the dust with acetone.
  7. Apply a sealant to the surface and allow it to dry for 2 to 3 full days, depending on the weather.
  8. Refill your pool.

It’s important to note that matching the color of the repaired area with the rest of the pool can be difficult. Getting help from a pool technician will ensure the repaired area doesn’t look worse than before. If the surface of your pool is beyond repair, a technician can advise whether it’s necessary to completely resurface it with a gel coat finish.

Get Professional Repair Help

Even with these tips for fiberglass pool repair, fixing pools can be difficult and time-consuming. The color may not match exactly, which can make it look even worse. Clear Tech Pools is your pool expert. With over 30 years of experience in pool maintenance, remodeling, and repairs, we’re here to help. 

Contact us today so we can fix your pool and you can go swimming again! We’ll be happy to assist you with any fiberglass pool needs.

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