This European Standard specifies the technical requirements for factory made flat or profiled sheets (wood-based, fibre cement flat sheets or corrugated bituminous sheets or other materials which can be characterised as one of these materials) that are used as underlays in pitched roof constructions with discontinuously laid coverings (e.g. tiles, slates). This European Standard also establishes methods of inspection and testing as well as criteria for evaluation of conformity.This European Standard does not include rigid underlays which have a stiffening function or a load bearing function.