Slate and interlayment roof and a method of preparing the same

A pitched roof having a deck, the deck substantially covered by a multiplicity of slate courses, each of the multiplicity of slate courses being comprised of a multiplicity individual slate members, each of the individual slate members having a substantially similar, generally rectangular shape including a lower edge and an upper edge and two side edges, each of the slate courses including multiplicity of slate members with their lower edges and upper edges aligned and their side edges aligned adjacent to other slate members of the slate course, at least some the slate courses of said pitched roof comprising:

• a first interlayment member, the first interlayment member being generally rectangular and having an upper edge and a lower edge, the first interlayment member for underlaying all of each slate member of the slate course, with the leading edge of the first interlayment member coincident with the leading of the slate course;
• and,
• a second interlayment member, the second interlayment member having an upper edge and a lower edge, the second interlayment member for overlaying part of each slate member of the slate course with the leading edge of the second interlayment member closer to the aligned upper edges of the individual slates members of the slate course then to the aligned lower edges and with the upper edge of the second interlayment member extending beyond the upper edge of the first interlayment member so as to partially overlap the first interlayment member.