1. How to check the flatness of the substrate?
1.1 The flatness can be checked by placing a 2 m straight edge onto the substrate, the straight edge should lay flat without any gaps.
- If there are some gaps, they should not be bigger than ±5 mm.
- The gap should not exceed ± 3 mm in the heavy-traffic areas or the areas using ready-mixed adhesive for tiling.
1.2 If more than 80% of the area conforms to the above standards, it is considered to be in a normal condition. If more than 20% of the area is not as the standards, the area has to be leveled with mortar cement mixed with weber.neo latex.