Logo for California Slate

California Slate Company, Inc.

3344 Market Street
San Francisco, CA 94114
+1 (415) 864-6862 Work
+1 (415) 814-2667 Fax
+1 (415) 710-9956 Cell
Globes and Quarry Image

Slate Shield: Lightweight Roofing System

Slate roofs are beautiful, long lasting, water-resistant, and fireproof — but they’re also heavy. A traditionally installed slate roof will weigh a minimum of 640 lbs./sq. when using a genuine “lightweight” slate. (If the roof weighs less, the slates are probably too thin to have a serviceable life span.) A traditionally installed “standard weight” slate roof typically weighs 900 lb./sq.

In the western United States, many residential and other structures were built to be roofed with wood shakes, wood shingles, or composite tiles, all much lighter than slate. However, many cities on the West Coast prohibit wood as a roofing material due to fire risks, and most composite materials have proven problematic. If slate is preferred for its durability and fire-resistance, but the structure is not designed for the weight of a traditional slate roof, a Slate Shield roof system may be the answer.

Instead of the heavy rafter system required by traditional installations, the Slate Shield process utilizes a series of butterfly hooks that are pre-applied to a water-repelling panel. This fast and affordable system creates a lightweight application as well as superior attachment of the slate to the roof surface.

The Slate Shield method uses half as many pieces as a traditionally installed slate roof, and so weighs in at 400-500 lbs./sq. while giving the appearance of a “standard weight” Vermont or Spanish slate roof. The 12″ × 10″ slate tiles are easy to handle, and because only the hip, ridge, and valley tiles are nailed, installation time is reduced substantially.

  • Slate Shield Installation Manual