How to Waterproof a Cinder Block Pool: DIY Steps & Guide

A cinder block is a frosty idea that has been around for many years. Typically, this project is faster and cheaper than the in-ground pool. It requires no liner, less exaction, and is easy to install. It is essential to protect any building from damage.

Cinder block installation is not very complex; you can do it easily. Its waterproofing ensures better performance. But do you know how to waterproof a cinder block pool? If you don’t, this guide is for you. Read more.  

A Step-by-Step Guide to Waterproof a Cinder Block Pool

Here is the step-by-step guide to waterproofing a cinder block pool. You can waterproof your cinder block pool successfully by following the below steps.

Step 1 -Arrange the Necessary Things

You will need many items and materials but below are some essential tools and materials that will ensure smooth working.

You will need a masonry waterproofer to waterproof your cinder block or concrete block structure. Laying the combination of cement, sealer, sealant will prevent water from seeping through the cracks.

Arrange blocks of size of 4×10 for the long side of pool and 4 x7 for the short side of the pool. You will need 2 x12 concrete blocks for the base of both walls.

Select the block type to waterproof the cinder block pool; you have two options. The first one is the mortar, and the other is the clinker blocks. Clinkers are a chunk of broken concrete required by a Portland-based product. While the mortar requires any additional sealant past that applied during the installation.

You will also need a high-quality sealant material for mortar sealing, arranged in enough quantity because you will need two or three coats.

Other tools you will require are a drill sprayer, trowel, safety fiberglass, and rubber gloves.

Step 2- Apply the Sealer

Start with sealer application; apply the sealer with the drill sprayer in an even stroke. You will need to use a plastic squeegee to remove excess sealant before drying. Because of the product’s viscosity and thickness, you can apply a second coat on the blocks.

Step 3- Mix Mortar

Mixing the mortar to apply to the cinder wall could take some practice. But it is a fact that it is one of the cheapest options. You will need a trowel for laying down the cement board on top of the blocks. But as you know, cement includes hard chemicals. So you will also need safety fiberglass and rubber gloves while working with the cement.

Step 4- Apply Mortar

After mixing the mortar, you should apply mortar on both sides block and the cement board. Then will have to place the piece of wood against the wall. So it is even on each side and trowel over top of that. While you have applied mortar, do not forget the edge because these edges meet water-tight needs. Now apply an extra layer of mortar at these points before the installation is complete.

Step 5- Remove Sealant

 In this step, you will need to check the sealant inside the pool and its removal. If there is any sealant inside the pool, it could make testing difficult and cause lots of problems in the future. You should also avoid getting any sealant on the water surface because it can make chemical testing difficult.

Step 6- Use Cinder Blocks

Using cinder blocks is easier, but sometimes it becomes challenging. The dark side of using cinder blocks is that they are not reusable. If you have installed them, you cannot get a second chance to remove or reuse them. But it is a fact that if you have done it right, your pool could last for years with the proper care.

Step 7- Install a Liner

A liner prevents water from seeping through the walls into the ground. So installing a new liner in the cinder block pool is necessary. It will make it easier to clean the pool and dry mortar before getting in and out of the water. If you are not installing a liner, you can apply a thick layer of trowel mortar over the top of the blocks.

Step 8- Apply Insulation

Proper insulation of the pool is essential when you are waterproofing a cinder block pool. Proper insulation of the pool prevents mold growth and algae from forming on the interior walls. In addition, the cooler it will be inside, the more water in the pool, and it also increases the life span of your cinder block structure.

Step 9- Shape the Ground Around the Pool

After doing the entire steps, you can ground around the pool and add other features to your project like stairs leading down to the pool, adding an earthen bank and plants, etc.

Step 10- Cover the Pool

In the final step, you will have to cover your pool correctly. Make sure that the cover is surrounded by outside parameters of the pool as much as possible. It would reduce evaporation due to the sun and prevent debris and dust from getting into the water.

How Could You Make a Pool Waterproof?

The protection of any building from water damage is essential for its health. To make your pool waterproof, I will recommend you use epoxy cement. It creates a solid barrier against counter-pressure and a resistance layer.

Does the Cinder Block Need to be Sealed?

Yes, cinder blocks require a proper sealer to prevent water from seeping. It is a fact that cinder blocks are endurable and adaptable, but through the edges, water could seep. You can seal them by using different materials and products available in the market.

How Many Sizes of Concrete Could be Used to Build a Pool?

A concrete foundation is comprehensive by 150mmdeep. That is laid around the pool perimeter on which the pool walls are built. Generally, the pool walls are made out of 450mm x 255mm x 100mm solid concrete laid to height.


Indeed a cinder block pool is the best option for building a pool. But you have to make it waterproof because you could not be able to fill it with water without sealing it. The water could seep from the corners of the pool.

Most of us prefer professional services for the installation of cinder block pools. It is an easy task if you follow the above step-by-step guide, but you only need to be careful when doing so.


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