Identifying the Biggest Causes and Solutions for Concrete Pool Cracks

woman sits on the concrete deck of her pool

Nothing Puts a Damper on Summer Fun Than A Cracked Pool – Here’s How to Fix It!

When properly constructed, a concrete inground pool can provide years of enjoyment for the whole family. But when corners are cut, problems are bound to arise.

One of the most common problems associated with concrete pools is cracking in the concrete. This article will explain what causes pool concrete to crack. We’ll also provide some solutions to help restore your pool to its former glory. Before you know it, you’ll be back to lounging by the pool-side worry-free!

What Happens When Pools Crack?

Cracks in concrete are quite common. They develop when stresses in the concrete exceed its strength – this can sometimes be due to natural causes, like shrinkage that occurs as the concrete dries and hardens over time. However, oftentimes cracking concrete points to improper mixing and/or installation.

Superficial cracking can often be a simple maintenance item, but in some cases, it can point to more serious problems that could severely affect the lifespan of your pool. When rain or pool water seeps through cracks in the concrete, the moisture penetrates the soil under the concrete deck. This will inevitably lead to more cracking. The more moisture that gets into the surrounding soil, the faster the damage will accelerate.

Either way, it’s important to address a cracked pool as soon as you notice it, to protect your pool’s longevity and integrity. With just a little TLC, a quick repair will greatly improve the durability and wear of your pool’s concrete surface, prevent corrosion in the reinforcement steel and reduce its permeability. This will ensure that the concrete elements of your pool are not compromised, and you’ll be able to enjoy it for years to come.

Top 5 Causes of Concrete Pool Cracking:

1. Improper Winterization

Before you close your concrete pool for the winter, it’s important to take the proper steps to ensure that the winter elements will not cause damage over the coming months.

You may be aware that water expands when it freezes. This means snow can be a huge problem, especially when it seeps into cracks in the concrete. Snow will put intense amounts of pressure on the concrete, resulting in damage and cracking. This can occur over and over again unnoticed as the months go by, worsening the damage each time. When the weather begins to heat up again, the contraction that occurs as the concrete begins to dry out again can compound the damage that has occurred over the winter.

To prevent this, drain some of the water down to the equalizer line – but not too much, or the pool floor may “heave” and cause a large crack in the bottom. There needs to be enough water pressure on your pool floor to keep it from moving over the winter. After you’ve drained your pool, you can also prevent raveling asphalt by applying a sand slurry seal to exposed areas on your pool surface.

2. Natural Shifting of Pool

Concrete is a naturally heavy substance, so if your lawn has any amount of slope, the pool could shift and become “out of level.” Shifting can also happen due to soil movement. You can tell a pool is out of level by looking at the water level in relation to the horizontal grout line around the pools edge. It should be equal all the way around. The more out of level your pool is, the more it will crack.

Another natural shift that can sometimes occur is “floating,” which occurs in areas that have high ground water levels. This causes your pool to literally float upward from hydrostatic pressure, which in turn causes minor cracking. It is important to keep up with these types of cracks as they occur, before they get deep enough to cause serious damage.

3. Failure to Seal Superficial Cracks

This probably goes without saying, but it is important to deal with cracks in your concrete pool as they occur. What begins as a shallow, superficial crack can become deeper and more serious over time. The more time that passes, the more moisture will seep into the crack and the more your concrete will expand and contract. It would be a lot easier to simply seal those irritating, superficial cracks as you come across them.

4. Lack of Proper Expansion and Control Joints

Quality contractors will be fully aware that concrete cracks. That being said, during installation they should have placed control joints and expansion joints in the concrete when it is first poured. Usually, expansion and control joints are placed in areas that will experience the most stress as your concrete pool is subjected to the elements, reducing cracking in the long run.

On the other hand, if your contractor did not properly install the expansion and control joints, you may have to completely dig them up, replace them and repour the concrete in those areas. It’s much easier to simply ensure your contractor has put in quality work from the offset. This is one of the biggest reasons why you should not attempt to install a concrete pool yourself. Why not hire an experienced professional instead? After all, it’s better to be safe than sorry.

5. Poor Compaction

Often, contractors do not take the time to compact the soil around your concrete pool the way they would with a concrete foundation for, say, a house. Your contractor may have also been hesitant to put too much compaction force on the soil around the pool. In any case, poor compaction will make it easier for your pool to shift and move, causing cracks. It can also cause the soil to settle and create voids under the pool deck.

How to Fix Concrete Pool Cracks:

Sealing Cracks

Using a sealant to repair cracks in your concrete pool is quick, simple and easy on the wallet. It also happens to be one of the most beneficial things a homeowner can do to help maintain their pool and prevent more damage later on.

There are different types of sealants on the market. Some are rigid in nature, others are elastomeric – meaning they will stretch or contract as the concrete moves. Elastomeric sealants are a little pricier than the more rigid variety, but we recommend them for their flexibility. This is important, because your pool will be doing a lot of expanding and retracting over an entire summer of splashing.

Pool Putty

Pool Repair Putty is a pliant, kneadable type of epoxy that mixes quickly to repair damp or wet areas. This is a great option for cracks on the pool floor, or in other areas that are fully submerged by water. It will bond instantly to fibreglass, metal, wood, concrete, ceramic, glass, and most plastics including PVC. Pool putty is a semi-permanent solution that sometimes comes in different colours to match your pool’s surface aesthetic.

Applying Fresh Caulk

If sealants and pool putty are not doing the trick, you can apply fresh urethane caulking for a longer-lasting and more durable solution to concrete pool cracks. If it’s a big crack, start by pushing your foam backer rod deep into the crack with a space of about a quarter-inch between the rod and the surface of the concrete. Then you’re free to apply the caulk and smooth for a finessed finish. If you’re dealing with a small crack, a backer rod won’t be necessary.

We recommend keeping the caulk off your bare hands and clothes – it’s quite sticky and can be a nuisance to remove. Wear disposable gloves, and if you do end up getting some on your skin, a quick wipe with a cloth dampened with paint thinner should remove it.

High/Low-Pressure Injection

Pressure injections, which normally use polymer resins, are another semi-permanent solution for pool cracking. Depending on the pressure level required (a low-pressure injection often suffices for small, shallow cracks) injections will force the sealant deep into the crack, which means less maintenance and less concern about re-cracking. A bonus to pressure injections is that they also offer a degree of structural reinforcement. They can be a little more expensive, but definitely worth it if you need a longer-term solution!

Torque Lock Staples

If you’re looking for a more heavy-duty solution, you may be interested in trying torque lock staples. These provide up to 5,000 pounds of controlled compression for long-term resistance to shearing, separation or other movements that can cause re-cracking or leaking later on. Torque lock staples use a concrete stitching technique to stabilize the crack for a permanent solution that won’t need to be reapplied or touched up as time goes by.

The Takeaway

Overall, inground concrete pools are quite durable and usually last for years, especially with proper maintenance. But if you went to open your pool this spring and noticed some cracking, there’s no need to be alarmed.

Even though it’s probably not serious, it is still wise for pool owners to seal cracks regularly and keep an eye on it to prevent future damage and ensure there’s not something bigger happening beneath the surface. This will ensure that you don’t have to deal with more expensive repairs later on. It also helps reduce trip hazards, allowing for fewer scraped knees and more fun.

Still have questions or concerns? Give us a call and we’d be happy to discuss your options.

Concrete Ready Mix Truck

Over the past 30 years in the Ready Mix Concrete business TRP Ready Mix has completed several commercial and residential projects, both large and small. Some of the more notable projects completed include;


  • Completion of several bridge pours on 417 highway
  • Water Tower in Russell
  • Large Agricultural barns

Contact Information

AL Blair Construction
7 Labrosse, P.O Box 220
Moose Creek, ON K0C 1W0, Canada

Phone: 613-538-2271
E-mail: [javascript protected email address]