How do I level uneven concrete, asphalt or tiles?

Uneven concrete, asphalt or tiles should be levelled with a material that is compatible with the existing substrate and appropriate to the depth of the irregularity.

For shallow irregularities in concrete, use a suitable patching compound or repair mortar. Larger defects in concrete should be filled with repair concrete. Asphalt surfaces are repaired with a suitable asphalt repair compound. On tiled surfaces, use a levelling compound suited to the intended application; loose or damaged tiles must first be secured or replaced.

Small depressions where water collects can be levelled beneath loose-laid tiles made of rubber granules by cutting roofing felt to fit. Several layers of roofing felt may be placed on top of one another where required. Check the result with a long straightedge or a straight metal rule.

This roofing-felt method is suitable only for localised irregularities and does not replace any necessary substrate repair.

Sand, gravel and chippings are unsuitable for levelling bound surfaces. Their loose particles cannot be compacted permanently and may shift under load or due to water movement, creating unevenness again and leaving the tiles laid over them unstable.