How to ensure that your external tiled area is waterproofed

By Tal | 2014-12-10

As the rainy season raises its head, you may come to realise that your balcony was not sealed or waterproofed correctly. Carrying out the proper background preparation procedures in waterproofing exterior suspended areas before tiling takes place is essential. This ensures the prevention of water leaking through grout and adhesive, which can cause tile failure if it seeps into the substrate or lower levels. The result is water damage shown on ceilings and walls of the levels below a balcony or terrace. It must be noted that this could also happen it the water outlet on the floor of the outside tiles area is not draining properly, thereby flooding the balcony.

Porous natural stone tiles and even light-coloured ceramic tiles stand a chance of changing colour when the tile installation experiences moisture ingress from the surface of the installation. The best way of determining the root of the problem, is to consult a professional tiling contractor. Of course, it is possible to waterproof and tile over existing tiles, provided the existing tiles are in good condition and firmly attached to the substrate – but ensure that the tiles are not cracked, loose or hollow sounding, and that the level of the current floor allows for a height increase, especially concerning door entrances. That being said, if the waterproofing system has failed, the most thorough solution is to remove the tiles and start the waterproofing and tiling process from scratch. It is best to attend to the water damage as soon as possible, before leaks cause damp patches on the ceilings of rooms below the installation.


Steps to follow when waterproofing and tiling an area exposed to the elements:


Waterproof the substrate with an acrylic based liquid waterproofing system, a waterproofing compound which is available from tile and home improvement retailers. TAL offers TAL SUPERFLEX, an acrylic based liquid waterproofing system which is acrylic-based and does not re-emulsify if exposed to water once fully cured, and the compound is also UV resistant and flexible.

You will need:

Step 1: Priming

  • Ensure the substrate is in good condition, clean and dry.
  • Prime rough, porous surfaces with TAL FLOOR PRIMER and smooth, dense surfaces with a TAL FLOORKEY slurry coat (one part TAL FLOORKEY to two parts tile adhesive powder or 1.5 parts ordinary Portland cement, by volume).
  • Paint the primer onto the surface using a block brush, and allow to dry completely before proceeding.

Step 2: Application

  • Apply a 10mm silicone bead in all internal corners and interfaces to allow for movement. Take care to ensure that the silicone bead is not flattened out and allow the silicone application to cure for 12 – 24 hours.
  • Apply a first coat of TAL SUPERFLEX to corner and interface areas. Bed the TAL SUPERFLEX Membrane, 200mm wide immediately, into the wet TAL Superlex1 and ensure that there are no wrinkles or air bubbles trapped beneath the membrane. The membrane must be pushed into the corners, to further ensure that the entire interface is covered with TAL Superflex1 Membrane. Then apply a second coat of TAL SUPERFLEX to completely saturate the membrane before the first coat dries.
  • For the primary area of application, apply the first coat of TAL SUPERFLEX over the clean, primed surface. Immediately bed the TAL SUPERFLEX Membrane into the wet TAL SUPERFLEX. Ensure that there are no wrinkles or air bubbles trapped beneath the membrane and that the membrane is adhered to the substrate by pressing the membrane with the roller in two different directions. Apply a heavy coat of TAL SUPERFLEX over the membrane to completely saturate the membrane before the first coat dries.
  • Check that the main application overlaps the corner applications by at least 50mm.
  • Allow the TAL SUPERFLEX system to dry completely for at least three days (depending on ambient conditions) starting your tile installation.
  • Never start the waterproofing application if it is about to rain as rain will dilute uncured TAL SUPERFLEX and cause run-off. Protect the system from rain or water immersion for at least three days after the application.


Step 1: Tile selection

  • Use slip-resistant and textured tiles when tiling an exposed and wet area. If you are considering natural stone tiles, remember that they require additional sealing after installation.

Step 2: Adhesive and grout system

  • Use a rapid- or quick-setting adhesives as, due to the impervious nature of the waterproofed substrate, standard-setting adhesives will take longer to set.
  • The adhesive and grout system must be able to accommodate thermal expansion and contraction in the installation due to temperature fluctuations and frost. The tile installation also has to be water resistant as it will be exposed to rain.
  • Use a water resistant and flexible adhesive and grout system to install the tiles. Mix the adhesive and grout with a latex additive, such as TAL BOND to achieve this system.
  • When using a latex based additive in the adhesive or grout mixture, use the full amount of additive as stipulated in the instructions on the packaging. The latex additive should be used as a total water replacement in the mix - never dilute the latex-based additive with water as this will weaken the mix strength and the adhesive and grout will not perform to their designed specifications in terms of enhanced flexibility and water resistance. 

A latex-based additive improves the water resistance of the adhesive and grout, but doesn’t make the installation waterproof, something to keep in mind as you approach you tile installation process.



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