Roofs are built to serve the dwellers, creating shade, protection, and enclosure. Meanwhile, they are the most challenging part of rural construction, especially with limited material sources. The Nubian Vaulting technique provides a non-formwork low-cost solution. The project parametrizes this fabrication technique with construction constraints and material inputs to optimize material use, costs, and structural behaviors. Instead of highly customized design and precise manufacture with machinery, the project examines manufacture-aware structures that can be built by local communities. The optimized design expands the category of pitch vaulting structure for the scale of housing units with the constraints of local materials and vernacular construction techniques.

 

The optimization is realized by DSE/Grasshopper/Rhino. There are 500 Latin Hypercube samples tested in the design space. Because form-finding variables are tested together with the other three variables, not all of the results are valid in terms of the construction method introduced in the paper. Two objectives are examined to filter the results to focus on buildable structures using pitched vaulting. The final design derives from the traditional Nubian vaulting technique but has an elevated ending arch. The inclined side walls stabilize the vaults in process. The end arch is flatter than the start arch. The design keeps the essence of the construction method as the final form is still a ruled surface that can be simply controlled by using connecting straight lines. The course angle is around 85 degrees, which needs to be further investigated with other material property inputs like friction factor and cohesion of in-layer mortar.