Does an uneven surface need to be levelled before laying tiles?
In most cases, levelling is unnecessary. Tiles made from PU-bound rubber granulate are elastic, and their ability to conform to the base depends on their thickness and density. Thinner tiles flex more readily and follow the surface beneath them more closely. Slight variations, hairline cracks, joints and shallow holes can usually be bridged without preventing the tiles from lying flat and stable.
More pronounced hollows in which water could collect should be levelled before laying, as moisture may otherwise remain beneath the tile covering. One practical approach is to fill the hollow gradually with suitably cut pieces of roofing felt. Add one layer at a time until the surface is even.