Exactly what has gone wrong recently is that imported slates produced from inherently less strong rocks have been split to traditional British thicknesses of around 5mm. The outcome is that on a roofing the thinnest slates in a consignment break during the first winter season. These don?t all break of course considering within the range of thicknesses in a consignment some; most likely most; will really stay strong enough. But this really is no comfort when five % out of a new roof covering try lying regarding ground; even when they did not hit somebody in the way down.

Established British roof thicknesses