This part of BS 8000 provides recommendations on laying cementitious levelling screeds and wearing screeds. It makes recommendations and gives guidance on basic workmanship for conventional types of building work.
The main changes in this British Standard from the previous edition take account of the following.
a) The terms used for the types of screeds take account of developments in European standardization. Screeds are designated “levelling screeds” where they are to receive a final flooring and “wearing screeds” where they serve to provide the finished surface.
b) Bases to carry rigid insulation boards beneath floating screeds are to be levelled by filling depressions so that the boards do not rock on high spots.
c) The specifications for materials have been updated. In particular European Standard specifications for cements now include a number of cement types and standard strength classes.
d) The use of higher slag content cements (>35%) and the equivalent combinations have been excluded from levelling screeds due to limited experience of their use.
e) The bags of cement now supplied by the manufacturers have been halved in weight to 25 kg so mix calculations have been modified.
f) Slurry bonding of the edges of day work joints is recommended before laying fresh screed material to help reduce curling at butt joints.
g) Items of work to be checked during progress, as well as on the finished screed, are listed.
h) The recommendations given in BS 8204-1 and BS 8204-2 are referred to for curing when using cement lower than strength class 42.5 N.
