What is the minimum underlayment thickness required for ceramic tiles where supports are spaced over 300 mm?

The minimum underlayment thickness required for ceramic tiles where supports are spaced over 300 mm is 12 mm. This thickness is essential to ensure the stability and durability of the tile installation. A thicker underlayment helps to provide adequate support, reducing the risk of cracking or breaking the tiles due to movement or flexing of the substrate beneath.

Generally, when tile is installed with spans exceeding 300 mm between supports, the underlayment must be adequately robust to distribute the load effectively and support the weight of the tiles without deflection causing damage.

Other thicknesses, while they may offer some degree of support, do not meet the specific requirements for this scenario. Thicker underlayment may not be necessary, and thinner options would fail to provide the structural integrity needed for such installations. Therefore, 12 mm is recognized as the standard minimum necessary for ensuring both performance and longevity in these specific conditions.