Roof Structure for the Amazon region

A new concept of wooden roof structure with an attached ceiling is idealized for construction in tropical climates. A scissors truss system is used for roof structure dictated by architectural considerations. The roof structure was developed using computer aided design in order to achieve an optimized construction system. This prototype project uses 3 trusses spaced 2.75m over a 5-m span, with a 5/7 slope, and a 60-cm overhang. The top chord and web members consist of 5x15 cm mixed hardwood species at 18 % moisture content. The roofing material is composed of 5x10 cm wood joists spaced 50 cm on center, 1x8 cm T&G wood panel ceiling, asphalt sheet, 1.5x3 cm wood strips spaced 30 cm on center, and clay tiles. The use of a wood panel ceiling, besides its aesthetic appearance, is ecologically and economically correct by diminishing the amount of wood used in roof structures when compared to conventional systems in Brazil. This design also, inhibits the occupancy by undesirable bats under the roof, because there is little gap between roof and ceiling. This prototype project was built two years ago in the Amazon tropical rainforest, under extraneous adverse weather conditions: six months of severe rainfall and six months of severe heat and sparse rainfall. Monitoring the structural and material behavior for the past two years it is evident the applicability of this construction system for adverse environmental conditions of high heat and humidity together