Can a Slate Roof Really Last 400 Years?

There are certain materials that are known to withstand the test of time and it’s no different with roofing materials. Materials like clay and slate tiles have been found in ruins of ancient cities dating back thousands of years and chances are those tiles could be reused a new roof today. We recently received an interesting question, can a slate roof really last 400 years? Let’s answer that question and explain why this material has been known to last decades and even centuries.

Can a Slate Roof Really Last 400 Years?

The short answer to this query is oh yes, definitely but how can this simple material stand up for so long. Let’s look at slate itself. Slate is a type of homogenous metamorphic rock consisting mainly of a mixture of volcanic ash and clay. Different regions will produce different compositions of slate but most slate is a large percentage of quartz with a mixture of other compounds like muscovite or pyrite. These compounds are pressed on by the weight of the earth for centuries and even millennia until the rock is the slate we think of.

This pressure and composition aligns the structure of the slate to create an extremely strong and durable material so when you’re covering your roof in slate, you’re essentially covering it with a tough stone armor.

Because there is little to no organic material in slate, it can take hundreds of years for the material to degrade despite being beaten my wind, snow, rain and other outside elements. This means that as long as nothing catastrophic happens, the slate can stand strong for decades and even centuries depending on the type and thickness of course. Chances are that a slate roof will long outlast the building it is protecting.

We can’t find any immediate examples of currently standing slate roofs that are over 400 years old, though we have found examples of several that were been built in the early 1800s clocking in at around 200 years old. So all theory seems to say yes, if it and the building it’s resting upon are well maintained we can see a slate roof really lasting 400 years or more.