Slate Roof

What is a Slate Roof?

Natural Stone is the ultimate eco-friendly, durable, and beautiful roofing material. Unfortunately, high cost and weight concerns make slate a rare sight on run-of-the-mill homes. You’ll most often see slate roofs on churches, libraries, and government and university buildings.

Roofing slates are manufactured from natural stone. Slate is metamorphic rock that formed under intense heat and pressure underground. As stone, it is very hard and will not saturate with water, and is completely fireproof. Yet it has a unique characteristic that allows it to be split into thin pieces that become roofing slates. Since slate is stone, it is impervious to weather, sun, heat, and cold so you can expect a slate roof to last a lifetime.

The color of slate is determined by its chemical and mineralogical composition. Since these factors differ in various locations, it is possible to obtain roofing slates in a variety of colors and shades. Upon exposure to the weather, all slate is changed slightly in color. The extent of this color change varies with different slate beds, being barely perceptible in certain slates. Those slates in which the color only slightly are classed as “permanent” or “unfading.” Those in which the color change is more marked and varied are known as “semi-weathering” and “weathering” slates. North American slate deposits currently producing roofing slate are found in Vermont, New York, Pennsylvania, Virginia, Quebec, Canada, and Newfoundland, Canada.

Cost of a Slate Roof

Slate that has been quarried for roofing is dense, sound rock, that is exceedingly durable. It is labor intensive–requiring specially trained workers to install which can be quite costly–$600-$1,500 per square installed. That said, slate is one of the highest quality materials you could select for your roof, so you will undoubtedly increase the value of your home.

Energy Efficiency of Slate Roofs

The density of slate can help regulate the temperature in your home, saving you money on your energy bills. You can also enhance the energy saving potential of your slate roof by:

  • Installing Radiant Heat Barriers: Radiant heat barriers are a thin layer of metal insulation (usually tin foil with a paper backing or a metalized mylar sheeting), which can reduce radiant heat transfer into your attic by as much as 95 percent when installed to the underside of your roof.
  • Installing Rainwater Catch Systems: You can reduce your water bills by installing cisterns or drums as part of your roofing installation in order to catch valuable rainwater for landscaping use.

In addition to saving you money on energy costs, a slate roof can also help reduce your environmental footprint. Slate is naturally occurring, contributing no toxic substances to the environment. Often capable of outlasting the life of your home, slate can also be recycled. Roofing waste accounts for more than 5% of the total waste sent to landfills across the nation every year. Since the majority of that roofing waste can be attributed to asphalt shingle roofing that needs replacement every 20 to 30 years, it’s easy to see the positive environmental impacts of installing a roof that is going to last 100 years or more.

slate roof

Maintenance of Slate Roofs

Installed properly, slate roofs require relatively little maintenance and will last 60 to 125 years or longer depending on the type of slate installed, roof configuration, and the geographical location of the property. Because of its longevity, slate is very cost effective over the life of the roof. Not only is the stone naturally highly rugged, it is very resistant to mold, mildew, and other sources of contamination making maintenance costs minimal. That said, broken, cracked, and missing slates should be repaired promptly by a professional in order to prevent water damage to your home’s interior and possible structural damage to framing.

Common Concerns with Slate Roofs

The weight of slate roofing tile ranges between 800 and 1,500 pounds per square (8 – 10 pounds per square foot). Before investing in slate, you’ll need to have your home evaluated from a structural standpoint to make sure it can take the weight.

Share this article