The Slate Roof
"A roof built to last centuries is not held together by chemical adhesives. It relies on the natural cleavage of stone and the simple hook of copper."
High above the stone cottages of North Wales, slate roofs have stood against the Atlantic rain for over two hundred years. Carved from Cambrian rock, this slate has a natural property called fissility, allowing craftsmen to split the heavy stone into thin, flat tiles along its natural planes of cleavage.
Unlike modern roofing materials that are glued or cemented into place, traditional slates are hung. Each tile is pierced with two small holes and secured to timber laths with copper nails. Because no mortar is used, the system remains flexible. As the building settles, the slates shift slightly, letting the wind pass through and the water drain away without cracking the stone.
We often try to glue our projects together with rigid processes and complex dependencies, hoping to prevent any movement. But the slate roof teaches us the wisdom of the loose fit. By designing modular, independent parts that can move slightly under pressure, we build systems that are easily repaired and endure for generations.