The exposedness to sunlight and traffic vibration directly affects adhesion efficiency when tiling on exterior area.


Porosity of tile adhesive and tile grout

Tile adhesive and grout are naturally porous, which allows water to infiltrate through the grout into adhesive layer and also the tile back. Things that should be considered when tiling on exterior areas are as the following.

1. Resistance property of the adhesive when being in contact with water

2. The structure must be strong enough to support the expected load including tiles, adhesive and grout. Terraces should be designed in such a way that there is a slope to allow drainage. In addition, under-tile waterproof system should also be considered before tiling to prevent water leakage onto lower areas.

The extreme of weather conditions.

The expansion of both tile and substrate is affected by the changes in weather -high temperature, direct sunlight and rainfall for instance. In fact the expansion rates of tiles and substrate are different, which can cause tiles to debond. It is then necessary to use high performance flexible adhesive to support these circumstances and at the same time to prevent tiles from debonding.

The larger tile size

The larger tile size, the less grout’s expansion-support efficiency. As a matter of the difference in expansion rate between tiles and substrate, tile grout being used has to be durable and flexible and the joint width should be at least 3 mm.


It is very important to use Polymer-modified flexible adhesive and grout to fix tiles on exterior areas and terraces. Another important point to consider is to use small size tiles because of their less expansion rates.


1. Surface preparation
  • The surface has to be flat and clean before tiling. The surface of terraces should be slope down to the drainpipe.

2. To fix tiles on terraces on balconies
  • To fix tiles on terraces on balconies, it is recommended to apply under-tile waterproofing system weberdry tex    
  • Leave waterproofing mortar to dry for 1 day before tiling.

3. Tiling with flexible adhesive webertai flex
  • Leave the tile adhesive to dry for 24 hours before grouting.

4. Grout the joints with webercolor outside
  • Joint width should be around 3 - 12 mm in order to absorb the expansions of tiles and substrates.   
  • Movement joints of 5 - 6 mm wide should be left at every area of 60 m2 and then seal the joints with special silicone sealant.   
  • All perimeter joints e.g. at tile corners, column corners and between two different materials, should be 5 - 6 mm wide and filled with special silicone sealant.

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