Concrete Pool Repair

worker repairing pool deck with trowel and concrete
  • 5-20 hours
  • Intermediate
  • 100-15,000
What You'll Need
Cold chisel
Safety goggles
Rubber gloves
Rubber boots
Concrete grinder
Pool trowel
White concrete mix
White sand
Acrylic cement-bonding agent
What You'll Need
Cold chisel
Safety goggles
Rubber gloves
Rubber boots
Concrete grinder
Pool trowel
White concrete mix
White sand
Acrylic cement-bonding agent

Having a swimming pool at your disposal on a hot summer day is a luxury. But when you begin noticing wear, it can quickly turn into a source of stress. When it comes to concrete pool repair, the most important thing to know is whether the damage is on the surface or if it’s structural.

The two types of repairs require different approaches, with structural repairs being more comprehensive and expensive. Surface repairs, on the other hand, can often be tackled in an afternoon. Here’s everything you need to know to be in the know.

Identify the Problem

You’re enjoying a nice cooling float with a cocktail in hand when you look over and see a crack in the side of the pool. Don’t spill your drink. Instead, put on your detective hat and see what you’re dealing with.

It’s important to address the issue quickly since a crack can indicate a problem that will get worse over time.

Surface Cracks

It’s not uncommon for concrete to crack. Think of the sidewalk in front of your house, the patio at your old apartment, and the steps on your grandmother’s porch. Because concrete includes aggregate material, when there’s a shift of any kind, those materials can separate slightly, causing a crack.

A surface crack can occur because of shrinkage or shifting, and they are relatively shallow by nature. Groundwater, poor construction, or freezing and thawing can also cause large or small cracks.

To identify a surface crack, give it a critical eye. If there are a group of small cracks, they are probably on the surface. Similarly, you can often see the back of a surface crack.

Structural Crack

Structural cracks, on the other hand, are extensive and may result in a pool leak. These cracks are often longer and/or wider than surface cracks. You might find them on the sides of the pool, along the bottom, or in the corners of the structure.

They can run in either direction. You may notice crumbling concrete or actually see all the way through the crack to the materials on the outside of the pool.

Changes in Water Levels or Clarity

Even if you don’t see a crack, you may have a leak you haven’t yet noticed. If your pool seems to need refilling more often than normal, water could be escaping into the surrounding soil.

Alternately, underground pools could experience an increase in water from groundwater seeping through a crack in the pool. This water may be dirty, or brackish.


When concrete breaks down and chips or flakes away from the surface, it’s referred to as spalling. This can indicate deterioration of the concrete material or a defect in the installation process.

Surface Issues

Your concrete pool repair may be on the surface, such as when the finish is discolored or stained. You might also find the surface to be excessively slippery and in need of a textured finish.

If you’re considering buying a home with an older pool, it’s worth getting a proper inspection to get an idea of what repairs you may be facing in the future.

worker repairing surface in drained pool

Concrete Pool Repair If Your Pool Is Dry/Drained

Once you’ve identified the problem areas, work through the steps below, completing each that applies to your situation.

If the damage is structural and comprehensive, you may want to call in professionals to complete the job.

But, with the proper tools and materials, you'll find basic concrete pool repairs can be easy if you use the six steps described below.

1. Remove Damaged Substrate

If your pool is drained, or the damage is above the waterline, remove any of the substrate or surface material, including patching or foreign materials.

This is a process similar to sanding down a deck before reapplying stain, or removing rust before sealing metal. You’ll need to get down to the healthy parts of your concrete pool and build it back up from there.

If there are cracks in the substrate, use a concrete grinder to cut them out and extend the cutout at least one inch beyond both ends of the original length of the crack. Remove all of the old, crumbling materials.

Note: Make sure to wear safety gloves and goggles when working with a grinder. Small particles can and will fly around during this process.

Then, with your chisel and hammer, make some pockmarks, or small grooves, on the pool's surface. These holes will help the patching material bond better to the pool's new surface.

2. Find Hollow Spots

Although you will be able to easily spot cracks in the pool's surface, it may not be as easy to identify spots where the outer plaster has separated from the shotcrete or gunite beneath it.

If these spots exist, they will most likely separate completely over time. It is best for you to repair these potential trouble spots while you are repairing your pool's surface.

You can easily identify these places by gently tapping on the pool's sides. At places where the plaster is separating, you will hear a hollow sound.

At the location of the sound, remove the loose plaster and replace it with the mixture you will use to fill cracks and holes.

3. Clean the Substrate Surface

Clean all dust, grit, and concrete pieces off the surface you are repairing. Then cover the surface with an acid rinse.

Warning: Working with acid is dangerous if the proper safety precautions are not taken.

Read the product’s directions thoroughly and wear rubber gloves, boots, splash-safe eye goggles, and an approved respirator for acid fumes.

Also, note you should never add water to an acid; always add acid to water. If you reverse this process, you could burn your skin via an explosive reaction.

4. Fill Cracks and Depressions

Fill the cracks with caulk, leaving a space of ¼ inch between the caulk and the top of the crack. This will allow you to later apply plaster without creating uneven places on the surface.

When finished with the caulking, let it dry for 24 hours.

5. Apply a Fill Mixture

Apply a mixture of white concrete, white sand, acrylic cement bonding agent, and enough water to create a mixture as thick as a thin putty.

With your trowel, force the mixture into all divots, holes, and corners, being careful to force out any air bubbles. Use your trowel to smooth the mixture over the surface until the surface is level and smooth.

Wait until the mixture has begun to set up, about 15 minutes, before smoothing the surface again with your trowel.

6. Texture the Surface

If the old surface has a texture that is rougher than your newly patched area, you will want to match the textures while your newly patched spot is still wet. You can do this by texturing the area with a damp sponge.

Now that you have repaired your pool surface, you should fill it with water right away. If you expect a delay in filling your pool, spread wet towels over the just-repaired surface.

concrete pool deck with cracks

Concrete Pool Repair Without Draining the Pool

For some repairs, you can tackle the chore without draining water from the pool.

This is a massive time and money saver compared to the alternative, especially when you consider not only the money spent on the massive amounts of water, but also for the additional chemicals and energy to heat it up.

Not all repairs can be made underwater, but if you simply need to fill a crack, you can accomplish it with the proper materials and techniques.

There are several effective products you can use, depending on the task at hand.

A filler is used to fill in cracks and add support to the surrounding structure. Joint sealers can prevent water from entering cracks and further damage. Patches can be used to cover larger cracks or areas where spalling has occurred. Grit additives can increase traction and reduce slippage.

One commonly used product is marine epoxy. These glues are readily available at home improvement stores, boat and trailer repair shops, and online. This is the easiest and most effective product for filling cracks as well as for replacing broken tiles beneath the water’s surface.

Note that some tile repairs require a thin-set-type cement. If using that product, the tiles cannot be submerged during the repair.

To make repairs beneath the water, you may need to use underwater apparatus such as a snorkel and goggles.

Repairing Concrete Pool Decking

If the problem is above and/or around the pool, you can often make the repairs yourself. The process for repairing and filling cracks is the same as it is for the inside of the pool.

Start by chiseling out debris from inside the cracks. Remove all loose materials and vacuum out the space with a shop vac or give it a blast with an air compressor. Then use filler inside the cracks and allow it to dry completely. Put a sealant over the repair for long-term protection.

Dealing with Spalling and Larger Cracks

If you have sections where the surface is peeling or flaking, you may need to refinish the entire pool or surrounding deck.

On the other hand, you may be able to simply patch the affected areas. The determining factor is based on the extent of the damage, your budget, and your preferences.

If patching, follow the same steps as those outlined for filling small cracks. Prepare and clean the area. Then apply patching materials. After drying, apply a sealant.

A Sinking Pool

Many pools encounter cracks and spalling as a result of the ground shifting beneath the surface. This is especially true if the pool is located on a hillside.

Raising the pool deck is a job for an experienced contractor. Ask around, get references, ask for testimonials, and hire out for this job.

The process typically involves drilling holes through the bottom of the pool. Concrete is then forced into the holes, which raises the foundation of the pool. When it reaches the desired height, the holes are filled and sealed.

Resurfacing Your Pool

After many years of wear or when the spalling is extensive, it’s best to resurface the pool deck. This will allow you to make repairs and also properly seal the entire surface as protection against chemicals, weather, and wear.

This is a big job and will likely be done by a professional. Whether you decide to hire out or stretch your DIY skills, it’s important to know what the job entails.

For starters, the existing surface needs to be prepped. Think of it in the same way as prepping a wall for paint. The surface needs to be clean and dry. It also needs to be treated in order to create a good bond.

The material used to resurface the pool can be tinted or even turned into intricate designs. Using a spray or a trowel, the material is spread and smoothed out. Texture and decorative effects are then added as required. Finally, the entire surface will be sealed.

Resurfacing your concrete pool and/or surrounding deck will leave the area looking fresh and new.

Use Caution When Draining Your Pool

If you do need to drain your pool for any reason, use the proper techniques to avoid catastrophic results. Improperly draining your pool can flood the ground beneath it. Believe it or not, this can actually lift the entire concrete pool, causing all kinds of issues.

It’s also better not to leave your pool empty for long periods of time. Empty or full, if you notice your pool rising, get a contractor on the job as soon as possible.

Pool maintenance ebbs and flows throughout the seasons, but it’s always part of owning the amenity.

If your pool’s due for some TLC, brush up on How to Lay Pool Tiling. If you’re still in the dreaming stages, look into the Pros and Cons of Natural Pools or even How to DIY a Cowboy Pool.