Assessment of the Moroccan vernacular timber roof: a proposal for an eco-friendly strengthening system

The Berber roof is a vernacular structure consisting of timber members, exploited for covering residential buildings or craft shops, characterized by a carpentry that was mostly developed in the Tangeri-Tétouan-Al Hoceima Region, northern Morocco. The simplest structural scheme consists of sloping common rafters supported by a ridge beam and the peripheral walls in such a way as to form a double pitched roof. However, in the case of wider rooms, a variation to the scheme often occurs, aided by intermediate “supporting structures”, placed at a very limited spacing through the roof, built in such a way as to reduce the bending deflection of the ridge beam and the roof pitches. These supporting structures are composed of king post truss shaped timber members; nevertheless, both in the choice of the member cross sections and in the connection joints, they look absolutely like original constructions. The solutions adopted by the local master builders have been analysed and verified by using FEM models, that have highlighted criticalities and pointed out the reason why these structures are very deformed nowadays. Lastly, a reinforcing system compatible with the local resources and techniques, used to preserve the surveyed Berber structures, has been devised.