Generally, riads are open roof in order to allow air, sunlight to enter the courtyard, butt today some riads have a roof or cover over the courtyard or have pitched roof edges to prevent an excess of rain to enter. Riads also consist of very few windows on the exterior walls, in order to allow for privacy. The walls often consist of clay or mud brick, whilst are also adorned with tadelakt plaster and zellij tile work.[75]