How to Tell if Pool Crack Is Structural: A Guide for Pool Owners

Addressing the concern: Pool Crack solutions for a seamless aquatic experience. Dive into expert repairs to ensure your pool remains a haven of perfection. Do you want to know how to tell if the pool crack is structural?  The top factors to consider are (1) size and length of the crack; (2) position; (3) leakage; (4) the look of the pool deck and pool wall.

These ways will ensure that you spot the problem.  Spotting the problem to act on it as soon as possible is the best action. Not doing so may ruin your idea of a relaxing pool party or a family swimming activity, or better yet, it may cause your business profits to dwindle. 

Before we delve into the ways to detect the reasons for having pool cracks, be that on the pool surface or any part of the pool, we need to understand these terms we will be encountering in this article.

Concrete Pools

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Concrete pools are one of the three major types pools are made of, the other two being fiberglass and vinyl liner.    A concrete pool is a mix of water, sand, cement, and a coarse aggregate of stone or gravel.

The pool shell is typically a concrete pool or fiberglass pool.  The pool surface usually has a plaster coat or a liner.  A concrete pool shell is created by spraying gunite or shotcrete.  

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Most in-ground concrete pools have 6 to 8 inches of gunite or shotcrete.  Gunite, by the way, is a dry mix with water in the sprayer, while shotcrete pools are already wet. 

You may use a dry concrete mix or the wet one.  Don’t worry about choosing either one of them.  Both of these methods produce the same results if done correctly.  But when is the proper time to resort to a concrete pool repair?

Pool Cracks

Pool cracks are some dents or cracks found on the walls or floors of a pool.  Pool cracks are normal, can be minor cracks, and can happen because of different reasons.  Understanding the reason behind the pool cracks to know how to fix them will give you peace of mind. 

What Causes Swimming Pool Cracks?

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There’s no good in worrying without knowing your facts.  You first need to know why cracks occur in your swimming pool before you think of ways to fix them.  Those pool cracks visible to you are often just on the pool’s surface.  The crack can just be a surface crack in the pool plaster and does not affect the swimming pool body itself.

Causes of Surface Cracks

Surface cracks are caused by the following pool problems that can be basically observed:

• Improper curing or any cementitious product like plaster coating or pebbles on the concrete deck areas (shrinkage cracks). 
• Not keeping the pool sufficiently moist after the concrete is sprayed can also cause structural cracking
• Leaving a pool empty for too long.  Doing this causes the surface to dry out and crack (because of excessive temperatures).  Imagine drying mud that you leave too long to dry.  It’ll crack, right?
• Acid-washing an old surface when attempting to clean it
• Wear and tear from age

Causes of Structural Cracks

Generally, structural cracks are caused by the following: 

• Earthquakes
• Flooding and major rain storms, which upsets the  foundational soil 
• Soil expansion, and contraction 
• Soil issues like the pool having been built on poorly compacted soil and failure to assess soil load-bearing capacity
• An improper pool build – not thick enough concrete or improperly spaced rebar
• The shallow end of the pool and deep end of the pool sit on two different types of soil, causing an uneven settling across the length of the pool
• Subsidence or when the ground underneath your house sinks 

Surface Cracks and Structural Cracks

Beware of the misconception that if there are cracks in a concrete pool, it is leaking.   Pool leaks depend on the type of crack in your pool. Let’s understand that there are two main types of pool cracks: Surface Cracks and Structural Cracks.

Surface Cracks

Surface cracks are shallow dents or damages that are visible in your pool and something that doesn’t indicate any pool leak.  Surface cracks don’t run through the shell of the pool.  So finding a remedy for pool plaster cracks and those that are shallow is easy.

Let’s look at the signs of surface cracks:

-smaller cracks, usually one line and may branch out to a  second or third (hairline cracks)

-appear in clusters

-plaster flaking away but intact underneath

-Very fine and can be in a spider-web pattern

Structural Cracks

When the damage caused leaking and deformity of the pool, then you have structural cracks.  Let’s look at the signs that may mean serious problems because of structural cracks.

• more noticeable from a distance
• a positive leak test
• a structural crack looks deeper
• the pool seems to be losing water
• there are rust stains.  Rust stains around a crack may mean it extends beyond the surface through the concrete shell of the pool and eventually reach the inner rebar.

Factors That Can Help Determine Structural Pool Crack

Determining whether a pool crack is surface-level or structural requires careful observation and assessment. Here are some factors that help identify the intensity of the pool crack: 

Size and Length

Try to examine the size and length of the crack.  Cracks that are limited to the pool’s surface (pool plaster) are superficial.  Superficial cracks are those that do not go through the pool shell, it is limited to the pool’s surface, such as the tile or pool plaster.

These cracks may be caused by aging, ground movement (shrinkage cracks), or weather changes.  You don’t need to worry about these cracks because they can be repaired without significant concerns.

It’s a different story if a crack appears to be deeper, that is it is going through the different layers of the pool structure.  Search for cracks that run through the pool shell, walls or floor.  You’ll notice these cracks are usually wider, and longer, and may even cause the parts to be separated or displaced.

Position

Surface cracks may appear like shallow fissures on the pool surface without bearing on the pool’s interior.

So, are cracks in the pool plaster normal?  Yes and no.  Although some cracks don’t run deep, there is also a chance that these are structural cracks.

If you see cracks that seem higher or lower than the other parts of the pool, it may mean severe crack-like bulging, leaking water, or shifting tiles, all pointing to structural cracks.

Leakage

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Water leakage is a significant indicator of a structural crack.  Monitor your water level.  If you notice a significant drop in the water level, despite regular maintenance and evaporation, water might seep through a structural crack.  Test it by marking the water level and observing it for a few days.  

If the crack is just surface level, it won’t have a significant water loss.

The Look of the Pool Crack and Pool Walls

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The look of the pool cracks and pool walls are significant factors to determine the intensity of the crack.  Structural cracks may be accompanied by visible signs of movement or shifting in the pool structure.  Irregularities such as bulging, sinking, or tilting of the pool walls or deck might be alarming signs.

Pool Crack Repair Methods

Staples

This method involves bending a piece of rebar into the shape of a staple and then dowelling and epoxying the staple over the crack approximately every 12”.  In our opinion, this is the least effective because it doesn’t secure against lateral/sliding movement.  However, it is the most economical option.

Epoxy Injection

This method is done by using small injector ports.  We will place small injector ports along the crack, covering its entire length and depth.

This is like superglue for concrete which is a great option for most mild to moderate cracks.

Stitching

We will trench through the crack to open and remove it in the stitching process.  We dowel and apply epoxy in additional rebar to add strength and then pack it full with high-strength concrete.  This is very effective, although more expensive, and is what we recommend when there are bigger cracks or for cracks that have reappeared after previous repairs.

Filling the Crack with Hydraulic Cement

Are cracks in the pool plaster normal? The answer depends on the type of crack you have in your pool. Cracks that are only surface level are a minor problem that can be repaired easily.  The best solution is usually to fill in the crack with hydraulic cement or have the area resurfaced.

A New Inner Shell

This is the most effective crack repair method although the most expensive.  The process is done by constructing an inner shell within the existing concrete pool body.  The contractor will line the pool with a second layer of rebar and then use shotcrete to add 5-6” of concrete to the pool.  This reinforces the entire pool.  

Typically, we only recommend an inner shell if there are several large cracks around the pool or if the pool has a high volume of big and small cracks throughout the entire pool.

Crack Repair Pricing as of 2023

Besides giving you expert advice on how you can fix pool Cracks that are bugging you, at Stanton Pools, we provide complete pool remodelling services, equipment repair, and weekly maintenance.

These prices assume repairs are done as part of a complete resurfacing:

• Staples: $200 per foot
• Epoxy: Typically $2,200 to $3,500
• Stitching: $350 per foot
• Inner shell: $20,000 to $25,000

Why Might Crack Repair Fail

A failed crack repair is uncommon but can happen.  

When cracks are repaired, the contractor is repairing the result of the problem, not the root cause.  

Soil Movement

Some forces may reopen a repaired crack, especially if the repair is not solid.

Improper Repair Method

Using a repair method that is inadequate for the severity of the crack may cause it to reopen or recur.

Another Crack in a Different Location

Sometimes, another crack reappears at a different location.  Pools tend to crack at a weak point.  If the repair makes the previous weak point is stronger, the pool may crack in an area that wasn’t reinforced (the new weak point).

What Can Happen if Cracks Are Left Untreated

If cracks are left untreated, several issues can arise:

If the crack is leaking, the leak can erode the very soil that is supporting the pool itself,  This can lead to more long-term problems and worse cracking.

Structural rebar within the pool shell can begin to rust and corrode from water penetrating the crack.  This will weaken the structure.

The crack can continue to grow, making repair more and more expensive for an in-ground pool, and it can even affect the foundation of your house.

Why Hire a Pool Expert

These possible issues will lead us to realize that some things are better left to the experts who specialize in crack repair and proper maintenance.  Also, they can walk you through the pros and cons of your decision which can help you spend less and build a sturdy pool that your family can enjoy for many years to come.

Since not all pool cracks require extensive repair, if you’re uncertain about the nature of the crack, or if it is more of a structural issue than it is a surface one, it’s advisable to consult a professional pool contractor or a structural engineer.  They have the tools and knowledge to conduct a thorough assessment.

Remember, these steps provide a general guideline.  Structural issues should not be ignored as they can worsen over time and compromise the integrity of the pool and even your house. Contact us today to address this potentially dangerous issue.