The main four different types of screed are below, although screeds can be tailor made using a range of admixtures to provide different qualities.
Bonded screed is fully bonded to the prepared concrete sub-base using a specialist bonding agent or primer. Often applied when thinner screeds are needed.
Unbonded screeds are laid onto a damp proof membrane or polythene sheeting, which separates the final layer of screed from the the concrete base substrate. Often applied to older concrete sub-bases.
Floating screed is laid on to a layer of thermal insulation, which is usually on top of a damp proof membrane that separates the existing concrete sub-base.
Underfloor heating screed is essentially the same as floating screed, but it is laid over underfloor heating pipes instead of insulating material.