While the material depends on the soil, the shape of the house often depends on the sky. Take, for example, the Provençal mas. With its thick walls, small windows, and stocky structure, it seems built to withstand a siege. That is exactly the case, but the enemy is not an army, it is the Mistral wind and the summer sun. Its design aims to keep the interior cool when temperatures soar and to offer as little resistance as possible to strong winds. The gently sloping roofs are no accident either: they prevent the wind from lifting the tiles.
In contrast, in western Brittany or Normandy, the challenges are humidity and storms. The Breton “Penty” (from “penn,” meaning “end,” and “ty,” meaning “house”) is often a low-lying house, sometimes protected by earthen embankments to shield it from the full force of the salty sea spray coming in from the Atlantic. Their roofs are very steep, allowing driving rain to run off quickly without seeping in.