TSW Roofing Solutions, Inc., Roofing Contractors, Forest Hill, MD



Historic Slate is a TSW Roofing Solutions Company that specializes in slate roof repair and replacement in Baltimore City, Baltimore County, Harford County, and parts of Cecil County. We have been accepted by the Maryland Historical Trust as a preservation contractor based on our successful completion of slate roofing projects on historic buildings, our compliance with standards and guidelines for historic preservation, and on customer references.

We hope the information here and in our blogs will deepen your understanding and appreciation of your historic slate roof.

Slate, a natural roof covering of enduring strength and beauty

Slate roofs have been among the world’s finest roofs for thousands of years. Slate is a natural, dense, quarried product. Because it is an intensely compressed rock, slate is durable, significantly fireproof, and essentially nonabsorbent.

Slaters are skilled professionals

A correctly installed slate roof is much more than an almost weatherproof covering—it’s also an enduring work of art. Our slaters are specially trained to have the right knowledge, experience, and tools to repair or replace your slate roof and deliver the best results possible.

Roofing slate quality

The region where it was formed and quarried determines roofing slate’s durability and approximate life expectancy.

Simply defined, soft slate softens (crumbles and flakes) more readily with prolonged exposure to weather, whereas hard slate resists softening. The American Standards of Testing and Materials (ASTM) developed an S-1 through S-3 rating system for roofing slate based on acid resistance, water absorption, and strength, among other factors.

Hard slates (S-1), such as slate from Pennsylvania’s Peach Bottom quarries can conceivably last for centuries on a properly installed and maintained roof. Softer slates (S2 or S3), such as those from the Lehigh-Northampton district of Pennsylvania, may last about 55 years to possibly 100 years.

A useful tip

If you’re thinking about buying a home that has a slate roof, be sure to schedule an inspection by a professional slate roofer.  A slate roof system requires particular know-how to determine the type of slate and its approximate lifespan and age, the quality of past repairs, and the condition of the flashings.  Understanding the details will help you make the best purchasing decisions.

Want to know more? Visit our blog for more information.