Tile installation after removing the old flooring

Structure type

Existing sand-cement screed, possibly with localized or widespread non-through hairline cracks.

Adhesive residues more than 5 mm thick. Tile installation on an existing screed with non-through hairline cracks.

Sand-cement screed more than 4 cm thick, bonded or floating, with or without an impact sound separating membrane, with hairline cracks (even widespread ones) caused by shrinkage, thermal expansion or variations in thickness of 2 to 30 mm. After removing the existing covering, the cleanliness and surface strength of the screed and any tile adhesive residues have been checked.
Leveling of unevenness up to 30 mm thick, whether caused by the base screed or by stubborn adhesive residues left after removing the old ceramic or stone covering, with the self-leveling compound RALLK UltraLevel K, at least 24 hours after spraying or brushing RALLK Primer K acrylic primer onto the screed to regulate water absorption and adhesion.
Primed or alkali-resistant glass fiber strengthening mesh of 150–160 g/m².
RALLK Kerasiv K Flex adhesive fully embedding the mesh, spread with a steel trowel to give a solid, uniform and even base for laying the ceramic or stone tiles.
Ceramic or stone finish covering laid with RALLK Kerasiv K Flex adhesive for indoor or outdoor ceramic or stone tiles in small or large formats.

After removing the old covering, check the soundness of the existing screed and of any adhesive residues, and make sure the substrate is clean, before starting any work.
Check that adhesive residues, and surface irregularities in general, are less than 5 mm thick.
Check that the cracks do not run right through the screed, breaking its continuity. If they do, they must be bonded with a suitable adhesive.
Check that the cracks are stable and no longer developing, and/or that they are not caused by stresses or loads still acting on the screed and making it move cyclically.
See the individual product data sheets for application methods and precautions.