The main benefit of a slate roof is its longevity. A properly installed and maintained slate roof can last up to 150 years and more making it one of the longest-lasting roofs.  

Unless you’re looking at a historic home, you probably won’t have to replace a slate roof while you own the property, but it’s always good to know the age.

There are two types of genuine slate – hard and soft.

• Hard slate is stronger and more resistant to weather and fire damage. It also doesn’t absorb water. 
• Soft slate isn’t as strong as hard slate, with a life expectancy of 50 – 125 years, it’s more durable than most other roofing options.

There are also imitation slate tiles, which don’t have the value or the longevity of real slate. 

So how do you spot fake slate?

• Real slate is a natural product, and the tiles vary in color and texture. If the slate on the roof is consistent in appearance, it’s probably fake. 
• Fake tiles also tend to be flatter and smoother than real slate.

The life expectancy of a slate roof will depend on climatic conditions, roof pitch, and slate quality. 

Climatic conditions and roof pitch are variable, however, ASTM International’s C406 standard specification for roofing slate establishes the expected service life for grades of slate:

• S1 - 75 years and over
• S2  - 40-75 years
• S3 - 20-40 years