design, materials, construction and quality of roof assemblies, and rooftop structures. Exception: ... crushed stone, crushed slag or waterworn gravel used for surfacing for roof coverings. BALLAST. ... (457 mm) wide, shingled between each course of a woodshake roof covering. MECHANICAL EQUIPMENT SCREEN.
Dec 14, 2010· Re: What Size Gravel Behind Retaining Wall? 10/30/2010 3:08 PM Mirra grid every 3 courses,3/4 stone 2' from the back of the wall,perferated 4'' sock pipe with 4" out lets in the bottom face of the is a calc for this for how high you go versus how far back you go with the mirra grid,ect.