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Ensure a tiled balcony is waterproof

On a tiled balcony it is essential to carry out the correct preparation and to waterproof exterior areas before tiling commences, to prevent water seeping through the grout and adhesive into the substrate, and consequently into the areas directly below. Failure to do this properly could result in expensive repairs.


Water damage to walls and ceiling  underneath a tiled balcony or terrace could be as a result of either the area not being waterproofed prior to tiling; the waterproofing compound being incorrectly applied or damaged; or that any drainage is blocked or not draining properly causing flooding of the balcony. Immediate attention is required to ensure that water leaks do not cause damp patches on the ceilings of rooms below the installation as this leads to peeling paint and costly repairs

Some tiles, particularly porous natural stone tiles and even light-coloured ceramic tiles, may experience a change in colour after installation due to moisture ingress from the surface of the installation.

Whatever the problem, if the waterproofing system has failed, it is recommended that the tiles be removed in order to start the waterproofing and tiling process from scratch. While it is possible to waterproof and tile over existing tiles -  provided the existing tiles are in good condition and firmly attached to the substrate - where tiles are cracked, loose or hollow sounding, or where the level of the current floor does not allow for a height increase, tiles will need to be removed and replace.

It is important to bear in mind that any tile installation is an aesthetic finish and does not act as a complete moisture barrier.

Here are some guidlines for waterproofing and tiling an area exposed to the elements:


Waterproof the substrate with a waterproofing compound such as an acrylic based liquid waterproofing system available from tile and home improvement retailers. TAL offers TAL Superflex1, an acrylic based liquid waterproofing system. This specific acrylic-based system does not re-emulsify if exposed to water once fully cured, and is also UV resistant and flexible.

Primer such as TAL Floor Primer or TAL Floorkey

Waterproofing system such as TAL Superflex1

Reinforcing membrane such as TAL Superflex1 Membrane

Block brush


Exterior silicone sealant

Step 1: Priming

  •  The substrate must be 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:

  • To allow for movement, apply a 10mm silicone bead in all internal corners and interfaces. Due care must be taken to ensure that the silicone bead is not flattened out. Allow the silicone to cure for approximately 12 – 24 hours.
  • For the corner and interface applications, apply the first coat of TAL Superflex1 to these areas. Immediately bed the TAL Superflex1 Membrane, 200mm wide, into the wet TAL Superlex1, ensuring that there are no wrinkles or air bubbles trapped beneath the membrane. The membrane must be pushed into the corners, ensuring that the entire interface is covered with TAL Superflex1 Membrane. Apply a second coat of TAL Superflex1 to completely saturate the membrane before the first coat dries.
  • For the main area application, apply the first coat of TAL Superflex1 over the clean, primed surface. Immediately bed the TAL Superflex1 Membrane into the wet TAL Superflex1. 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 Superflex1 over the membrane to completely saturate the membrane before the first coat dries.
  • Ensure that the main application overlaps the corner applications by at least 50mm.
  • Allow the TAL Superflex1 system to dry completely (at least three days, depending on ambient conditions) before commencing with tiling.


Don’t start the waterproofing application if it is about to rain as rain will dilute uncured TAL Superflex1 and cause run-off. Protect the system from rain or water immersion for at least three days after application.


Step 1: Tile selection

 Use slip-resistant and textured tiles when tiling an exposed and wet area. Avoid smooth and polished tiles. Remember that natural stone tiles require sealing after installation.

Step 2: Adhesive and grout system:

  • It is always recommended to use 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 has 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. This system is achieved by mixing the adhesive and grout with a latex additive, such as TAL Bond.
  • When using a latex based additive in the adhesive or grout mixture, it is important to 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. Do not 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.
  • Seal the grout and porous tiles after installation.

TAL products are available from major tile merchants and Builders stores countrywide.


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