The most trusted solution to prevent any damp seeping through your shower walls and floors is to waterproof your shower with Sika’s universal waterproofer and bonding agent, Cemflex®. Cemflex® mixed with Portland cement and water forms an effective waterproofing slurry that is used in conjunction with the Cemflex® membrane. Cemflex® can also be applied to waterproof Reservoirs, Balconies, Verandas, Fish Ponds and Retaining Walls.


What you will need

  • Cemflex®
  • Cemflex® Membrane
  • Portland Cement
  • Water
  • Wire brush
  • Block brush / large paint brush
  • Bucket to mix
  • Gloves
  • Mask
  • Spatula (small quantities) / mechanical mixer and paddle (quantities exceeding 5l).


Step 1

Ensure that the shower walls and floor are bare plaster and free of any dust or loose material. The walls and floors can be cleaned using a wire brush.

Step 2

Precut manageable pieces of Cemflex membrane for the required area.

In order to prepare the waterproofing slurry, you will need to mix 1 litre of Cemflex, 1 litre of water and 3.4 kg of Portland cement, which will yield 3,2 litres of waterproofing slurry that will cover an area of 1m² (with membrane).

A basic guideline:

Cemflex Waterproofing mixing ratio

Refer to the Cemflex® packaging for mixing instructions. First mix the required amount of Cemflex® and water and then add the correct amount of Portland cement slowly, while mixing, to avoid any formation of lumps. You will now have a Cemflex® slurry that is ready to be applied.

Step 3

Dampen down the walls and floor that you will be applying the product to and make sure that there is no standing water. Ensure that the walls and floor are thoroughly saturated and while the surface is still damp apply a coat of the Cemflex® slurry.

Dunk the Cemflex® membrane in the Cemflex® slurry until the membrane is fully saturated.

Remove the soaked membrane from the slurry and lightly squeeze before placing the Cemflex® membrane over the damp substrate with your gloved hand, smoothing off with the brush to eliminate all air bubbles. Overlaps of adjacent fabric must be a minimum of 50mm.

Step 4

Once the entire area is covered and all the air bubbles have been removed, apply a generous coat of the slurry and allow to dry for 24 hours.

Step 5

After waiting 24 hours, mix a new batch of the Cemflex® slurry and apply the final coat to the completed area. Allow the final coat to dry for 6 to 8 hours before applying tiles or painting the surface. Freshly applied Cemflex® should be protected from damp, condensation and water for at least 12 hours.