Rocks Used for Roofing

Sedimentary Basics

• Natural stone roofing material generally comes from sedimentary type of stone, such as slate. When quarried and hewn, they naturally form “sheets,” or layers of sediment that have hardened over time and have a variety of different colors and patterns within. These sheets can then be further refined into squares that are also used in flooring as well as wall coverings in homes and offices. For roofs, they are sold in tile format, although there are two different types: tooled stones, which are roughly the same shape, and rough stones, which are of varying shapes and dimensions and can be stacked together like a puzzle for a relatively flat surface on the roof.

Benefits

• Rock materials are superior to man-made products in the sense that they are weather-resistant. They do not fade from sunlight. They shed moisture. They do not erode with moisture and insect damage, such as wood shingles. Unlike asphalt shingles, they have zero environmental impact as they contain no chemicals. They do not retain ice and snow, and are not affected by environmental changes. On top of that, they are completely fireproof. Their density also helps insulate the home, which reduces energy consumption.

Installation

• Slate, which is a far heavier roofing material than normal shingles, has stricter requirements for the framing of the home to handle the load. Always contact a structural engineer to help in planning your natural stone roof to ensure proper support is given to the material. As far as installation goes, the basic waterfall principle is followed; each upper layer of stone overlaps the lower layer, and each upper row is staggered so that the joints running down the roof never match up from row to row. This ensures water always flows down to the gutters in a waterfall effect. Mounting the stones depends on the manufacturer’s requirements and ranges from hook-and-batten systems, epoxy cement applications and simply stacked-stone on top of a cement-based mortar.

Maintenance

• Asphalt shingles may blow away in heavy winds and require replacement, and wood shingles rot and require continual replacement as well as sealing and staining to retain their look and durability. But natural stone roofs are usually good as-is for the life of the home and beyond. The only maintenance required is an annual cleaning, which is done with a power washer from a ladder. This is only done to clean debris and remove any mineral buildup from rain and moisture. On the occasion that you need to fix a crack, epoxy stone repair kits are sold at any home improvement store.