Different types and thicknesses of screed will take different lengths of time to dry or cure. It should be left at least 24 to 48 hours before it is walked on, although with certain additives this time could be reduced to 12 hours. For heavier traffic, to have a floor covering laid on top or to move furniture and tools across it, it’s best to leave it at least 5 to 7 days. Most screeds will reach their fully cured strength after 28 days, so for best results, it's best to wait until then to use the screeded surface.