This variation, however, was only used in areas that were protected by strong dykes and was not adopted by Uthland-Frisian houses which occurred in regions endangered by storm surges. Even if the walls and the ground floor of such a post-and-beam house are destroyed by flooding, there is a very high probability that the upper storey will survive, so that the occupants of the house can take refuge on the roof. Ever since the serious North Sea flood of 1962, newly built Hallig houses have been given concrete posts with deep foundations in order to improve their safety still further. Another feature of the Uthland-Frisian house is that they were moved from time to time because they stood on warfts that could sink or become saturated over the course of the centuries, thus endangering the house. Because building materials, especially wood, were scarce and expensive, it was formerly common everywhere, to take the houses apart and move them if the warft was no longer safe or was otherwise abandoned. The walls of the houses were originally made of turves, clay or wood, most of the houses that survive today, however, have brick walls. Different types of brick were used. On the outer wall, hard and expensive, very weather-resistant bricks were used, whilst softer and cheaper bricks, the so-called Bleekers, were preferred for the insides of outer walls and for the interior walls. Timber-framed designs were and are extremely rare. Geestharden houses are usually thatched. To prevent rainwater accumulating in the thatch, the roofs have a very steep pitch. Most of the houses also have a gable dormer (Zwerchgiebel) with a half-hipped roof over the entrance, i.e. a gable that runs at right angles to the main roof ridge. This design enables the house to be evacuated in the event of fire without burning thatch falling on the escaping occupants. Accommodation In the living area are the living rooms and kitchen, a cellar and, above it, a cellar chamber (Kellerstuben). The kitchen has a chimney. The living area is normally on one side of a narrow hallway or Diele that runs from one side of the building to the other and has an entrance both at the front as well as at the back into the garden. This corridor (Flur) separates the living area from the working area. Döns The Döns or Dörnsch (Danish: Dørns) was a heated living room, in