Industry standards require a minimum of 80% coverage in dry areas and 95% in wet areas to ensure tile integrity. Voids act as stress concentrators; when weight is applied, the lack of underlying support allows the tile to flex and eventually snap. Furthermore, voids in wet areas can trap water, leading to mold growth and compromised waterproofing systems. Always use the appropriate notch trowel for the tile size and back-butter larger format tiles to maximize the contact area between the tile back and the mortar bed.
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Why is it important to check for full mortar coverage under tiles?
Full mortar coverage is essential to prevent void spaces that create weak points under tiles. Without proper support, heavy foot traffic or dropped objects can cause tiles to crack or debond from the substrate, leading to premature installation failure and potential safety hazards.