Plaster repair on porous clay or aerated concrete block masonry.

Structure type

Existing plaster based on hydraulic binders with hairline cracks along the block outlines.

Detail

Interior or exterior skim coat over plaster.

Application cycle

1. Standard plaster, class CS I – CS III according to UNI EN 998-1, with hairline cracks along the block outlines. Check its cohesion, strength and bond to the wall, and that it is clean and free of moisture, dust, residues of old poorly bonded paints or finishes, salt efflorescence, organic substances, oils and mold.
2. If needed, RALLK Primer K acrylic primer as a surface fixative or consolidant on poorly cohesive existing plasters.
3. Skim coat over the whole wall surface with the all-purpose skim coat RALLK Rasante K, RALLK K OttO or RALLK Raso K, with embedded 150 g/m² glass fiber mesh, laid from top to bottom with the vertical strips overlapping by at least 10 cm.
4. Finish with a finishing coat, RALLK Marmo K mineral finish or another powder mineral finish, acrylic, siloxane, lime or silicate paste finish, or lime, siloxane, acrylic or silicate paint, as set out in the specifications.

Additional information

1. Based on current site experience, a reinforced skim coat over cracked base plaster is an effective way to prevent the cracks from reappearing in the medium and long term as a result of minor settlement, vibrations or thermal expansion.
2. The fixing/consolidating treatment with acrylic primer can be skipped on cohesive, sound plasters (see step 2).
3. See the individual product data sheets for application methods and precautions.