Do Fiberglass Pools Crack Over Time?

If you are a fiberglass pool owner or are thinking of installing a fiberglass pool, one question that often comes up is, will a fiberglass pool crack? The short answer is yes, it is possible for a fiberglass pool to crack, but the explanation of the causes of a fiberglass pool crack is more complicated. Let’s take a deeper dive into the “do fiberglass pools crack?” question to give you a better understanding of installing and taking care of this type of swimming pool. 

Fiberglass Pools: A Quick Overview 

Before jumping into the causes and solutions for a fiberglass pool crack, let’s take a quick look at how fiberglass pools are made and installed. An understanding of these basics can provide a better understanding of why fiberglass pools crack, how to prevent that from happening, and what to do if they do.

Fiberglass is one of the three main types of swimming pools. The other two are cement and vinyl. Fiberglass pools are highly durable and, on average, have a lifespan between 20 to 30 years, and can last even up to 50 years, if well-manufactured and properly installed. A fiberglass pool crack is not all that common as fiberglass as a manufactured substance is both strong and flexible.

Fiberglass pool shells are manufactured off-premise and then fitted into an excavated and prepared hole in the ground, referred to as the pool foundation. The making of the fiberglass pool shell and preparing the pool foundation are important parts of the installation process. 

How Fiberglass Pools Are Made

Fiberglass pool shells are very large molded pieces of fiberglass that are manufactured through a multi-step process. The pool shell is created from a pool plug, a wood or steel frame that is used to mold layers of fiberglass, filler, and primer. This process starts with the applications of several gelcoat layers. The gelcoat is made from colored resin and gives fiberglass pools their color. After the gelcoat is sprayed with a vinyl resin several layers of chopped fiberglass are built on top of each other, giving the pool its signature strength and durability, allowing it to hold the weight of many gallons of water.  

How Fiberglass Pools Are Installed

Fiberglass pools are installed by first laying out pool measurements and specifications, and then excavating a hole that follows those specifications. Once the hole is dug the installer sets the pool floor to provide a stable base for the pool shell to sit. After this solid foundation is complete the pool shell is placed in the prepared hole. Then, the plumbing and electrical components of the pool are set up. This is followed by backfilling the area surrounding the pool while also filling the pool with water to maintain equal pressure on both the outside and inside of the pool. This process is followed by coping, decking, and landscaping. Proper installation is key to lowering the risk of a fiberglass pool crack. 

Fiberglass Pool Cracks: Risks, Causes, and Solutions

Overall, the risk of a fiberglass pool crack is very low. The fiberglass material used in this type of swimming pool is made to withstand tremendous pressure, but also remain flexible to the changes in the surrounding earth, including contracting, expanding, and settling. 

For a fiberglass swimming pool to crack, it has to be subjected to conditions that overextend its natural flexibility and durability. These are not usual swimming pool conditions, but unusual ones that can develop from improper installation or poor maintenance. There is also the risk that the pool structure is compromised due to a flaw in the manufacturing process. Fiberglass pools from reputable manufacturers, however, usually have considerably long warranties. 

Installation Problems

The development of a fiberglass pool crack depends a lot on how well your pool is installed. Improper pool installation can cause a ripple effect of conditions that can raise your fiberglass pool crack risk. Fiberglass pools can withstand immense pressure and also remain flexible, but cracks can occur with uneven pressure. This usually occurs when the pressure on the outside of the pool is greater than the pressure inside of the pool or visa-versa. 

Uneven Surface

If your pool is sitting on an uneven surface or foundation, it can cause unbalanced pressure and result in a fiberglass pool crack. This uneven surface can be caused by improper preparation of the pool’s foundation or leveling, or from excessive settling. Excessive settling can be caused by poor backfill material or a leak in a pool’s plumbing system.

Preventing this excessive settling can help prevent a crack in a fiberglass pool from developing from an unlevel surface. Using gravel as a backfill material is preferable to sand because it will not liquify when saturated with water. Installing proper return fittings along with a solid foundation and backfill can help prevent leaks from plumbing settlement. Preparing your foundation should be done according to your soil conditions. Your pool installer should be well-versed in the type of soil you have in your backyard. 

Water Pressure Issues

When there is an inadequate level of water in your pool, the pressure from the inside of the pool becomes uneven with the pressure on the outside. This can cause a fiberglass pool crack. It is important to always have an adequate level of water in your pool and to have it professionally drained if it ever needs to be drained, which is not often. The installation of a dewatering system with a pipe and skimmer lid can also help with water pressure issues. 

Gel Coating Issues: Spider Cracks

Another type of crack that can affect fiberglass pools are spider cracks. These are hairline cracks that appear and spread through the pool’s gelcoat layer. They usually develop over a long time and do not signify a structural issue with your swimming pool. 

Preventing a Crack in a Fiberglass Pool

Proper installation and maintenance is the best way to prevent a fiberglass pool crack from developing in your swimming pool. Staying on top of your pool maintenance and hiring a reputable and experienced pool installer goes a long way to ensuring pool longevity. 

How to Properly Maintain Your Pool

Following manufacturer’s guidelines and instructions to properly maintain your pool is important.

Routine pool maintenance includes:

• Check water levels and maintain an adequate amount of water in your pool according to guidelines.
• Clean your pool regularly. Remove debris, vacuum the bottom, and wipe down and brush the surface walls.
• Keep your pool chemicals balanced. A proper balance of chemicals keeps your pool safe, clear, and sanitary, and prevents algae from growing. It also keeps the chemicals from affecting your pool surface.
• Keep your water filters clean. Routinely change your pool’s air filters to prevent clogs and ensure proper functioning.
• Use proper cleaning products. All the products you use to clean your pool should be made specifically for use on fiberglass pools. 

How to Choose a Fiberglass Pool Installer

Overall, it is rare for a fiberglass pool to crack, but it is also clear that many of the main causes of a fiberglass pool crack occur during the installation process. This makes it even more important to choose the right fiberglass pool installer. Make sure to choose a reputable and professional installer who has years of experience installing this type of swimming pool. 

Your installer should be able to talk with you about the specifics of your installation, including:

• The placement and foundation of your pool
• Landscaping considerations
• Materials used and installation process
• Experience of their technicians
• Installation timeline

A professional installer should also be able to provide you with a list of customer references. 

Repairing a Fiberglass Pool Crack

If a fiberglass pool crack does develop in your pool, all is not lost. A professional fiberglass pool repairs can fix big fiberglass pool cracks or bulges. If the crack is minor, it can be repaired using a DIY pool repair kit. This entails sanding down the damaged area and applying an epoxy putty to seal the crack. Once dried, the area can be sanded smooth so a gelcoat can be applied and rolled smooth, and then covered with a sealant. A similar process can be used to repair spider cracks in your pool’s gelcoat layer. 

The Final Word on Fiberglass Pool Cracks

Will a fiberglass pool crack? Yes. Is it inevitable? No, it’s not. Proper pool installation and maintenance both go a long way in preventing fiberglass pool cracks. Finding a reputable and professional pool installer who specializes in fiberglass pools can help ensure proper installation. Following manufacturer’s guidelines and investing in keeping your pool well-maintained is the other side of the prevention equation. If a crack does happen, having it quickly and properly repaired can help prevent further damage and more expensive repairs down the road.