The job at Burley, near Ringwood, involved the specification of 400mm shingles in random sizes, laid with staggered or uneven butts in order to improve their natural characteristics.
The shingles needed to be fire retardant so were treated with FRT Exterior, a full-cell non-toxic pressure treatment process meeting BS 476: Part 3: 1958 giving a double AA rating, and BS 476: Part 7: 1971 giving a Class 1 surface spread of flame.
John Brash shingles are also treated in a vacuum pressure impregnation process with a copper-based preservative treatment.
