Laying Roof Slates
The above diagram shows the ordinary method of laying slates
with a 3-inch (7.62cm) lap. In unexposed positions slates can
safely be laid with the lap decreased to 2 inches (5.08cm).
Wide slates and increased lap are advisable for low-pitched
roofs, or very exposed positions.
Usual slating size: 2 x ¾
For small slates: 1½ inch (3.81cm) x 1inch (2.54cm) and 1¾
inches (4.44cm) x ¾inches (1.91cm)
Cwt-y-Bugail Quarry Booklet: The Architects' Guide to
Natural Slate Roofing
Please Note: Roofing regulations may have changed since
the above publication was produced in the mid 1990s, and new regulations have