Basket Roofs of Msungwi: A proposal for roof renovations of existing school structures for Msungwi District, Tanzania

             

As partners, the Tanzanian government and the American NGO Africa Schoolhouse  have established a new primary school for the Sakuma village of Ntulya. A local building crew trained on-the-job while constructing 12 school buildings and a Health Post. Ntulya School complex opened in 2011 and is now in session for 600 children.“Basket-Roofs of Misungwi”, an innovative renovation system, maybe the next collaborative step. The concept is for several site-constructed Basket-Roofs to be built by the now-experienced crew, to rehabilitate existing secondary school facilities and equalize the impact of NGO aid to the region.

Every aspect of the Basket was designed by considering local materials. It is built in place with thin steel reinforcement bars that are interwoven and wired together without welding. The cross-sectional dimensions between the upper and lower arc is determined in the field by connection to perimeter steel pipes and site-made x-bracing, also of thin steel reinforcement bar. The basket form is supported at a canted orientation to the ground by site-formed concrete columns that receive the steel edge pipes. The moderately stressed reinforcement bar offers high strength and long spans with minimal mass.The upper surface is prepared to receive roofing tiles that are pre-wired in long strips to be more efficiently laid and to align.  The lower surface is smooth plastered. The glazed tiles alternate between raised profile and flat for aesthetic and rainwater management parameters. The canted roof orientation augments natural ventilation flows and day-lighting.

The  module of the Basket Roof as shown in approximately 9.6m square set and 30cm square and 30cm x 60cm concrete columns. The modular structure adjusts to existing conditions since the Basket-Roofs are not depending directly on existing structures for support.  In fact, the mis-alignment of the new structure with the existing leads to useful accessory spaces for new programs such as lunchroom, circulation, playground.