Digitally fabricated low cost housing: material, joint and prototype

Motivated by the global housing deficit and limited natural resources, this study aims to utilize digital fabrication technologies coupled with local sustainable materials in the quest for alternative, adequate low-cost housing solutions for the less fortunate population, mainly in developing countries. The thesis is structured into two main parts: a theoretical and an empirical study. The theoretical part identifies the research problem and lays the foundation of knowledge, as well as defines the motivating questions, aim, objectives, scope, methodology and tools used throughout the thesis. An overview of fundamental concepts of mechanisation, standardisation, prefabrication, mass housing, and mass customisation is provided. Different types of prefabricated housing are presented followed by a discussion of select architect-led and industry-led early precedents in prefabrication. The theoretical part also includes an analysis of state-of-the-art built projects or prototypes of digitally fabricated houses. Through this analysis, how these prototypes respond to housing problems is addressed and an observation is made of how these built projects can be categorised into main streams or different trends. After defining the potentials and limitations of these precedents, a number of design criteria or design guidelines are proposed forming the basis for the proposition of a housing system that addresses these drawbacks under the name “Housing System 01”. The second part of the thesis is a Design-Build-Evaluate empirical study in which the proposed housing system combining concepts of complete off-site prefabrication with modular parametric localised digital fabrication is outlined. Given the necessity of cost reductions, an integral joining system (snap-fit) using an agricultural residue panel material is tested as the principal method for the construction of wall assemblies. The study proves that by using integral joints, it is possible to involve the end-user of the housing unit in the construction activities promoting the concept of “Self-Build”, as the simplicity of the system allows for the participation of end-users with no previous construction expertise thereby decreasing cost. A set of mechanical tests are performed to characterise wheat straw panels and then snap-fit joints are dimensioned within the elastic limits of this specific material. Three partial wall assembly prototypes are built. One axial compression test is performed on one of the prototypes. The tests show that the material and the joint system promise to provide a viable construction system as an alternative low-cost housing solution. Further optimisation and more physical structural testing are needed to address more complex forces and loading scenarios.