How to Repair Fiberglass Pool Walls

Best Selling Fiberglass Cleaner

Fibreglass pools offer unrivalled novelty, among other advantages that concrete pools cannot attain. These pools are also easy to maintain and more durable, making them more popular as time goes by.

Most swimming pool owners also find them convenient since they require fewer chemicals and scrubbing. Nevertheless, they can sustain cracks or bulges occasionally. If your fiberglass pool has a crack, don’t panic because you can fix it with the right repair kit and guide.

Below is a step-by-step guide on how to repair fiberglass pool walls.

Factors to Consider Before Repairing a Fiberglass Pool Wall

1. The Color of Your Fiberglass Pool

Nowadays, most pool owners use colored fiberglass for their pools. While the colors add an elegant look to your pool, it can be challenging to match them during repairs. Luckily, most of these pools do not require repairs before they reach 20 to 40 years.

To avoid color mismatch, you have to consult an experienced technician and work with a solid surface finish. Although the repairs may not replicate the original fiberglass pool, you can get one that is almost similar to it.

You can begin by researching several fiberglass pools manufacturers to confirm if their colored finish is multi-layered or solid finish. This will help you get a finish that is close to your fiberglass.

2. Size of Cracks in the Gel Coat

Is your pool having a spider or structural crack? The size and type of the crack determine how the repair is to be executed and how long it will take to complete it. It also informs you whether you need to hire a skilled swimming pool technician or do it yourself.

Hairline cracks are usually a minor problem that does not affect the pool’s structure. Generally, they form on the gel coat or surface layer and do not spread to the structural laminate layers. Thus, they only affect one area of the pool, which makes them safer.

Structural pool cracks usually measure ½-inch deep and extend 1-inch in length. These cracks may mean your pool is leaking or will eventually leak. In such situations, you may have to remove the particles and sander down the area.

3. Pool Walls Bulges

Pool wall bulges differ from cracks since they mostly occur due to the pool backfill. When the sand liquefies and exerts excessive pressure on the fiberglass, it starts to bulge if the surface is not strong enough to put up with it.

While it can be challenging to identify the most stable and strongest fiberglass, you can execute a few practices to prevent bulges. They include

  • Using un-filled resin since filler weakens the pool.
  • Building a thick pool between 3/8 to 1/2 inches depending on the pool area.
  • Using a well-designed laminate schedule that will produce a stronger structure that can withstand the pressure.
  • Utilizing structural comb supports on the sidewalls of your pool to increase resistance to the bulges. To ensure the “ribs” are effective, space them appropriately.

Knowing the type of repairs required and the color of your fiberglass will help you acquire the right materials or hire an expert. You can always give your swimming pool surface a clean look!

How to Fix a Crack or a Hole in Your Fiberglass Pool Wall

Empty Pool

Before a pool repair, ensure that you have all the tools ready. Some of the tools you will need include.

  • Fiberglass repair kit, or you can use automotive kits.
  • Diamond-edged cutting wheel
  • Electric disk sander
  • Paint roller
  • Masking tape
  • Putty knife or air sprayer

Here are the steps you should follow when repairing pool cracks

Step 1. Drain the Pool and Examine the Damage

It’s easy to conclude that the crack in your fiberglass is the reason why you are experiencing sudden pool water level drops. However, water droppings in the swimming pool are not always a consequence of leaking water. Thus, it is essential to inspect the extent of the damage before attributing it to cracks.

To fix the crack, begin by draining the pool and allow it to dry for full access to the spot. After you drain the water, assess the damage, whether it’s minor or structural. Minor pool cracks will need a different method of repair compared to major ones.

Some pool owners will fix the cracks when the pool is still wet, which can be challenging. Additionally, the repairs may not dry properly, causing them to reappear again. To avoid this, make sure the damaged spot is dry enough by either allowing it to air dry or using towels.

Step 2. Sand the Damaged Spot

Using an electric sander, polish the area around the crack or bulge. Sanding the section will remove any peeling paint or dirt. Do not sand the area manually as it will not be smooth like when using an electric sander. After sanding the section, utilize a dry rag to wipe the sanding dust.

Mark an area around the crack that is approximately 2 inches. Then replace your sanding disc with a diamond-edged cutting wheel to cut out the area you marked. Ensure you cover the depth of the crack to eliminate it.

For easy pool repair, work carefully to leave smooth cuts with definite lines. Wipe away any dust left on the spot with a dry rag.

Step 3. Apply the Bond Coat

After you are done making the cut-out, mix the hydraulic cement in the fiberglass repair kit according to the instructions. Then apply the bonding with a putty knife on the cut-out.

Smooth the bonding to ensure it is flat and you have an even surface, then allow it enough time to dry (tacky consistency). If the hole is small and is not leaking water, you will not need hydraulic cement to patch the pool wall.

Step 4. Apply Polyester Putty

Before you grab your polyester putty, you need to apply an epoxy to catalyze a chemical reaction to repair the damage properly. The higher the ratio of the putty to the catalyst, the faster the drying time and the harder the layer will be.

You don’t want more bumps on your fiberglass pool surface, so ensure the putty is smooth. To accomplish this, you can either level it with a putty knife or a scraper. After drying, use an electric sander to smooth the entire area and wipe away any residual dust with acetone.

At this point, you will start seeing some progress in your pool repair. But there is one more step to go to complete the repair and restore the stunning look of your pool surface.

Step 5. Apply Gel Coat and Fiberglass Cloth

To apply the gel coat, begin by attaching a masking tape approximately 2 inches around the patch. Then apply a gel coat with a paint roller; alternatively, you can use an air sprayer to achieve a more even coat.

While the gel coat is still wet, apply the fiberglass cloth and roll the patch with a ribbed roller. Perform this carefully to ensure you eliminate all the folds and air bubbles. Make sure you cover the entire 2 inches around the spot.

Apply another coat and allow it enough time to dry. Then sand it until it’s smooth, and wipe any residual using acetone. To complete the pool repair, apply a sealant coat and allow it to dry properly before you can refill the pool. Drying may take between two to three days, depending on the weather.

Most experts recommend you contact a reliable company with competent technicians to assist you with color choices. This will help you avoid creating an unsightly section than the crack or bulge.

Alternatively, if the damage is extensive, the technician may advise you to do the entire resurfacing of the pool with a new gel coat finish.

How To Prevent Fiberglass Pool Problems and Damages

Well-maintained Fiberglass Pool

1. Maintain Your Fiberglass Pool

Maintenance is essential in every pool and can prevent serious damages that may cost you dearly. The good thing is that fiberglass pools require low maintenance, and when you take care of them accordingly, they can serve you for decades.

Unlike vinyl and concrete pools, the gel coat makes them non-porous hence it’s harder for the water to permeate through them and damage the pool surface. Additionally, algae are rare in fiberglass pools compared to concrete pools; you can eliminate their chance by executing maintenance practices.

Some of the maintenance practices that will see your fiberglass pool serve you in the longterm with no damages include

  • Regular cleaning
  • Assessing the chemistry of your pool’s water using a chemical testing kit.
  • Running the pool filter and utilizing an automated pool vacuum.
  • Always keep the water level above the pool skimmer.

When cleaning the fiberglass pool, use the right non-abrasive cleaners to prevent hairline pool cracks or water chemistry disturbance.

2. Apply the Right Thickness of Gel Coat

Gelcoat spider cracks often appear due to pressure exertion at a specific point of a fiberglass pool. When the gel coat cannot flex enough to withstand the force, it cracks. So, what causes the pressure?

Three things can contribute to pressure-related problems, and they include:

  • Improper manufacturing
  • Improper shipping
  • Improper installation

You may either have the company building fiberglass pools that are under or overly thick. These two affect the flexibility of your shell and the tenacity to withstand pressure.

You may also have shipping problems that lead to cracks. You need to communicate to the company and have the shell replaced if you don’t want to have repair costs piling immediately after installation.

Installers tweak and lift the pool to level it and can cause tremendous pressure on certain parts in the process. Consequently, cracks may appear immediately or over time.

Contracting a manufacturer who applies the right gel coat thickness and makes leveled fiberglass pools can help avoid this. You also need a contractor who can install the fiberglass with care and level it properly.

3. Plumbing Settling and Pool Discoloration

Plumbing (backfill material) doesn’t settle; instead, the fiberglass pool settles and carries the plumbing with it. However, when using sand, it’s difficult to compact it completely as you install the pool.

Despite trying to saturate it with water, it settles over time. Settled plumbing causes leaks which can be disastrous to any pool owner. To prevent this, use gravel backfill material that does not settle.

Discoloration damages the aesthetics of a pool, but you can prevent it from happening. To avoid discoloration, purchase a fiberglass pool that is well manufactured, follow the manufacturer’s best practices, and maintain the water chemistry.

Frequently Asked Questions

1. How Much Does a Pool Repair Cost?

Pool repairs’ costs vary depending on the type of pool and the damage extent. For instance, if you want to hire technicians to resurface your fiberglass pool, you may have to part with $6,500.

However, this also depends on the size, shape, and age of the pool. Another factor that may influence the cost is the finishes; the more expensive they are, the higher the pool repair cost.

Since fiberglass pools can have holes, bulges, or cracks. Each damage may need different tools and effort to eliminate. After you drain the pool and inspect the extent of the damage, you will determine the amount of money you need.

Usually, if the crack is deep into the surface, it will cost more. But, if you are dealing with spider cracks, it’s cheap to fix.

2. How Do I Chose the Right Fiberglass Pool?

Most clients who want to purchase fiberglass pools are anxious since they don’t know how to identify the right thickness or properly manufactured pools. While it’s challenging for a non-technician to identify these issues, you can maneuver through this successfully.

All you need to do is call a few close friends or relatives who have dealt with the manufacturer. Find out whether they got top-quality fiberglass pools that could flex and if they served them long enough.

This approach will help you eliminate the possibility of installing a damaged (with cracks or holes) or improperly manufactured pool. You can also apply this approach when searching for a contractor to install the pool.

3. Can I Fix My Pool Damages?

Are you experiencing leaks or paint problems? Depending on the type of damage or problem you have, you can either do it yourself or hire an experienced technician. For instance, if you have a spider crack that does not penetrate beyond the surface, you can follow the guide’s instructions to fix it.

Nevertheless, if you have sudden and significant pool water drops caused by extensive structural cracks, you need to call a pro to repair it. Such damages demand experience, and the process of repairing is more intense. Thus you need an expert who can come up with solutions even in the worst situations.

If you plan to repair, have your paint roller, repair kit (to mix the cement), among other tools ready. Remember, you don’t have to bear the pressure alone; you can always call an expert to help you!


Have you noticed cracks or bulges on your fiberglass pool surface? Don’t panic, you can fix them yourself or with the help of a competent technician. All you need to do is drain the pool water to determine the extent of the damage.

If it’s manageable, follow the instructions above for the best outcome. However, if it’s extensive, call a pro to fix it for you!

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