Slate

Slate is a natural product that is cut out of the ground, sawn into blocks of designated size and then split by hand into shingles. The primary slate quarries in the United States are located in New York, Vermont, Virginia and Pennsylvania. The desired grade of slate used for roofing is S1. Common colors of slate are: black, gray, green, purple and red, as well as variations of these colors.

Slate is available in standard sizes ranging in length from 12 to 24 inches and widths from 6 to 14 inches. Slate can be ordered in thicknesses ranging from 3/16” and up, with standard thicknesses ranging from 3/16” to 1/4”. The weight of a slate roof system with standard thickness slate is approximately 700 to 1,000 pounds per square (100 square feet), and if 2” thick slate is used, the weight would be approximately 8,000 pounds per square.

A slate roof system is comprised of the slate roofing, high-quality underlayment and flashings. The long-term success of a slate roof system is dependent on proper specifications and installation of all three components.

The slate can be installed in generally three different methods: standard system, graduated system and textural system with multiple variations of each, and are secured to the roof with corrosion –resistant nails. The exposure of the slate is determined by the pitch of the roof and the size of the slate.

The flashing and underlayments should be specified using materials that will last in a manner consistent with the service life of the system. Maintenance on existing slate roofs is required to maximize the life of the system. Maintenance would typically involve replacing any broken or missing slate to prevent premature deterioration of the underlayment and checking flashings. Repairs in a leaking slate roof usually involve removing the slate, installing new underlayments and, if needed, the flashing and re-installing the same slates.

Your representative at Garlock-French is ready to assist you with all of your slate roofing and repair needs.