SUBSTRATE DIAGNOSIS BEFORE TILING

1. The flatness can be checked by placing a 2 m straight edge onto the substrate

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.

2. The area has to be leveled with mortar cement mixed with weberneo latex.

• 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 weberneo latex.

1. This check mainly concerns wooden floors laid on joists or battens

• This check mainly concerns wooden floors laid on joists or battens, wooden panels and, more rarely, partitions.

2. The flooring strips or wooden panels should not move when they are stepped on.

• The flooring strips or wooden panels should not move when they are stepped on.Partitions should not flex when press by hand.

3. If this is not the case, reinforce the floor, replace the boards, or brace unstable partitions.

1. Check the surface hardness by scratching it with a pointed tool e.g. a nail, in several places.

• The scratch has to be superficial.
• If the surface peels off, it is not hard enough for tiling.

2. Plaster walls should be brushed with a stiff brush and then wiped to remove any loose material.

• Plaster walls should be brushed with a stiff brush and then wiped to remove any loose material. Also check the in-depth hardness of existing screed or plaster walls.

3. The defective surfaces have to be removed until sound material is reached.

1. Pour a little amount of water onto the substrate.

2. If the water is absorbed in less than 1 minute, the substrate is considered as excessive porous and requires priming.

1. Check the adhesion of existing tiles by tapping with a hammer.

2. Any hollow sounding tiles or tiles with poor adhesion have to be removed.

3. Replace by similar tiles or tiles with the same pro-perties.

1. To check the adhesion of existing paint, carry out a cross-hatch test using a suitable knife or cutter.

2. Score the paint in small 2 x 2 mm squares over a total area of 10 x 10 cm. Use transparent tape to stick onto the area and then pull off quickly.

3. The paint is considered suitable for tiling if 80% of the area of the small squares remain bonded. If not, the paint has to be removed mechanically.

1. Eliminate any traces of plaster with a scraper. Carefully remove any dust and any other stains.

• Apply weber.prim 2 primer, if necessary, on existing tiles, paint, wood or PVC tiles to increase the bonding property.
• When do the tiling on existing paint, remove any traces of varnish or wax and apply weberprim 2 primer to ensure a good adhesion.

2. For cement, light-weight concrete or gypsum-based substrates; a primer to decrease water absorption should be applied.