How long should a scratch coat be cured before applying a mortar bed?

The correct answer is 24 hours because a scratch coat requires this duration to adequately cure and achieve the necessary strength and adhesion before the application of a mortar bed. Curing is critical as it allows the moisture to escape gradually, preventing issues such as cracking or delamination once the heavier mortar bed is placed on top.

This 24-hour curing time ensures that the scratch coat has sufficiently hardened to support the additional layer and provides a stable base for proper adhesion. If insufficient time is allowed for curing, the integrity of the installation could be compromised, which may lead to defects in the tile setting or unintended shifts in the layers, ultimately affecting the longevity of the tiling project.

While shorter curing times might seem appealing for speed, they can lead to significant problems in the long run, highlighting the importance of following established standards for optimal performance in tiling applications.