One of the most important considerations if you’re building a house is materials. In the past you’d almost always build out of local materials. It’s just too costly, to haul stones or logs or whatever very far. So if you had a cave, you live in a cave. If you have sticks and reeds, sure, it’s a stick or reed roof. And, if all you have is stones? Yes, you can make a stone roof!
Ths is a lauze roof, made out of pieces of stone. These are not fastened into place with anything but friction. Each piece is hand-shaped and laid into place without mortar or glue. The steepness is an essential feature, allowing the tremendous weight to be supported as much as possible by the walls. Here’s another image of a different one, where you can see the actual thickness of the layer of stone. These roofs weigh tons!
Compare to this little number. It is a capitelle, a dry stone shepherd’s hut in the highlands of southern France. The roof is the simplest possible stone construction, but the principles are similar. There are no rafters here, the dome is just worked slowly inwards until it can be capped at the center with a large flat stone. A capitelle can’t be much bigger than this. If you want a wider roof you need rafters to support the stones, as lauze roofs do.
Here’s the guy doing it. He told us he’s been doing this for forty years. You can see the horizontal pieces of wood, and the bigger stones wedged between them. Then little stones are inserted, carefully chipped into shape and canted so that they sheds water. There are inevitable gaps between the stones — they’re not Lego blocks. But this is a feature, not a big. A lauze roof is airy in summer and yet watertight without benefit of plastic film or weatherstripping.The big down side to them is the tremendous weight, and the difficulty of finding anyone who does this kind of work. They’re cruelly expensive, calling for finding the exact right local stone and then getting them all up to roof level.
But have a look at this roof, on a chateau. Incredibly beautiful, and astoundingly precise. This is the work of a master. A roof like this will last for two hundred years. It is so difficult and costly, that the next step is the one I’ve already blogged about — making roof tiles. Clay or slate was the cheapest and best roof until modern asphalt shingle. But it’s all worth it, to stay dry!