At right-hand verges and right-hand side abutments, Right Hand Half Slates must be used in alternate courses with Mini Stonewold, Richmond, Saxon & Landmark Slates.
At left-hand verges and left-hand side abutments, Left Hand Half Slates must be used in alternate courses with Mini Stonewold, Stonewold II, Richmond, Saxon & Landmark Slates.
At right-hand verges and right-hand side abutments, Slate-and-a-Halves must be used in alternate courses with Cambrian Slates.
At left-hand verges and left-hand side abutments, Left Hand Verge Slates and Left Hand Verge Slate-and-a-Halves must be used in alternate courses with Cambrian Slates.