The interior walls of the house in fez

The interior walls of the house are covered with simple plaster (gyps), which was not painted. Again this allows the walls to "breathe", and helps to keep the house cool and dry in the summer. Every few years a new thin layer of plaster would be added, and when it got too thick, all the plaster would be removed and a new layer added. Carved decorative plaster is used above and around doors and windows, and below the ceiling. The plaster is applied to the wall, a design is incised, and then is carved in situ. Natural colors, similar to those used in the zellij and wood, were applied to highlight the designs or calligraphy, but much of the surface was left unpainted. A date (in the Islamic calendar) is often found in the center of the plaster panel above one salon door, but this is the date of the completion of that plaster, and almost never the date of the construction of the house. It's common to have a six-hundred-year-old house with zellij, plaster and wood that's less than two-hundred years old, since some elements of a house would be changed or replaced every one to two hundred years.