Slate Roofing
Slate as a roofing material peaked in popularity in the late 1800s. The move away from steep roof slopes and the availability of less expensive roofing products have caused the slate roof industry to shrink greatly in size. Slate roofs are expensive too, costing as much as $900 per square (100 feet) compared to say, $60 per square for an asphalt shingle roof.
Nevertheless, the National Slate Association and the Slate Roofing Contractors Association of North America agree that slate possesses an “extraordinary life expectancy.” In fact, a slate roof can actually be taken apart and largely put back together. Naturally, broken slates, worn flashings, and rotting sheathing boards would need to be repaired, but the slate itself is recyclable virtually forever. A 120-year old slate roof could continue serving the structure at 200-years old. But repairs are best done by the professionals who recognize that any part of a slate roof can be removed, repaired or replaced, as long as the slate is still good.
One might ask what makes slate “still good?” The answer is simple; it is still good if the exposed surface is smooth, free of pervasive “delamination,” flaking or other signs of deterioration. The word delamination refers to the condition when the layers of slate separate from each other.
There are a few important points to know about slate roofs. First, it is a myth that slate roofs require felt underlayment. Felt is only employed as a protection against rain during the installation of a roof. It is fine, even if the felt is completely worn to a powder under the slate. The slate roof still will not leak. If a roofer tells you to replace a roof because the felt is worn out, that advice is incorrect.
A good place to ask questions about slate is the public slate roof central message board, called slateroofcentral.com, or you could contact one of our certified roofing contractors.
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