The general Rockcote acrylic resin based finishes are not designed for, and have limited ability to bridge cracks in masonry substrates, other than micro or hairline shrinkage cracking.
They cannot be used or expected to bridge structural cracking caused by substrate movement. In Rockcote Quick Render and other cement based applications; this crack bridging ability is even more limited, due to the rigidity imparted by cement.
Treatment of Relief Joints
Cement based renders and most texture coatings should not breach or be applied over relief joints (expansion, control, movement or articulation), as these types of joints are designed to support movement and settling of buildings and substrates and the coatings can potentially crack at these junctions.
Render and texture coating systems should be applied up to and away from such joints, leaving the joint free of excess material and debris.
If required, a coloured topcoat system can be applied to give a uniform finish across the wall.