4 Steps for Waterproofing Pools


Swimming pool leaks are frustrating – and addressing them is often expensive, time-consuming, and sometimes requires removing tile and adhesives. To help your clients enjoy their pools without interruption, consider using a waterproofing and crack isolation membrane.

Selecting a Waterproofing Method: Tile pools, as described in P602 of the TCNA handbook, require a cementitious waterproofing product over their concrete shells. These products address both negative hydrostatic pressure, which is water pressure that comes from beneath or behind the pool’s substrate, and positive hydrostatic pressure, which is pressure placed on the substrate from above, by the water in the pool.

You can additionally address positive hydrostatic pressure with a waterproofing and crack isolation membrane, which can help prevent water from leaking into the mortar bed. This membrane helps prevent problems associated with saturation and moisture expansion and is applied to the substrate’s surface and allowed to cure before tiling begins. Its crack isolation properties are particularly important in freeze/thaw environments. Look for a membrane that allows for the direct bonding of tile for an efficient installation.

If you opt to use a waterproofing and crack isolation membrane, follow these steps.

1. Smooth the Substrate

You need to bring any variations in the pool’s wall or floor (the mortar bed bonded to the cementitious waterproofing), within acceptable flatness levels. TEC® Fast-Set Deep Patch mixed with XtraFlex™ can be used effectively in this application for swimming pools.

2. Clean the Substrate

To facilitate a strong bond for your waterproofing membrane and the tile, ensure that the substrate is properly prepared. Proper preparation requires removing any contaminants on the substrate’s surface – including grease, residues and dust; as well as all loose materials, such as those resulting from honeycombing or laitance. Possible methods for cleaning include pressure washing, scarifying, sandblasting, shot blasting and grinding. After final preparation, remove all dust by vacuuming, clean the surface with a wet sponge and let it dry before applying the membrane. If the concrete has no contamination, you may only need to scrub and wash it.

3. Apply the Waterproofing Membrane

Apply the waterproofing membrane of your choice as per the manufacturer’s instructions. TEC® HydraFlex™ Waterproofing Crack Isolation Membrane can be applied by roller, trowel or spray over concrete as new as three days old and cures in just two to three hours. Prior to coating the entire surface with the membrane, pre-fill all concrete cracks up to 1/8” wide. Flash all control joints, substrate joints, field seams and corners; anywhere vertical surfaces meet horizontal surfaces, such as curbs, bench seats and columns; anywhere dissimilar materials meet, such as drains and expansion/control joints. All flashing should be done per the product instructions using Waterproofing Mesh

Once flashing is complete, apply the membrane to the entire surface using a 1/4” to 1/2” nap roller, 3/16” v-notch trowel or airless sprayer. Apply one coat in a minimum thickness of 25 mils wet. Allow this coat to dry for 1 hour, or until the membrane becomes semi-transparent, and then apply a second coat 25 mils wet, at a right angle to the first coat.

4. Test for Leaks

Once the membrane is properly cured, test to make sure the pool is watertight before beginning the tile installation. To do so, fill the pool at a slow rate. For comparison, fill a test vessel with water and keep it next to the pool. Measure the water levels of both the pool and test vessel after filling, and again after several days. If the pool and test vessel have lost similar amounts of water, evaporation or wind are probably the culprit. However, if the pool has lost significantly more water than the test vessel, you will need to drain the pool and make repairs to the waterproofing system.

Phase testing can help you isolate the source of any leaks. Fill the pool partially – below any fixtures in the wall – and conduct testing. If no leaks are detected, fill the pool above the first level of fixtures and repeat testing. Again, if there is no evidence of a leak, fill the pool and conduct a final test. If a leak is detected at any stage, drain the pool as much as necessary to conduct repairs.

Your customers are probably eager to get their pool up and running. But don’t let that encourage you to skip steps in the waterproofing process. Properly waterproofing a pool – and checking its effectiveness – helps ensure that your clients will be able to enjoy their pool all season.

Questions? Contact our Technical Support Team for any help on your next tile installation job. You can also call 1-800-832-9023, Mon-Fri 7 a.m. - 6 p.m. CST.

Posted by
TEC Staff