Geometry and Proportion: Materialization of an Architectural Carpentry Project

This paper deals with the works of the so-called “white carpenters”, people directly or indirectly designated for tasks related to the construction of buildings. Focusing on the carpentry works for creating building roofs in the Spanish territory, from the VIII century onwards we can find two types of carpentry: Muslim and Castilian. The architectural influences between these two types of woodworkers originated a new solution for interlaced framework structures, called “armaduras de lazo”. They consisted in a particular “par y nudillo” system (with jointed rafters) applied to timber roofs having four (or more) pitches, which presented decorative motifs derived from the Islamic geometries. The paper aims to analyze in detail the geometric rules that characterize the architectural and structural composition of the “armaduras de lazo” roofs. In particular, the generation process of the “par y nudillo” structures are based on the assembly of sets of eight, nine or ten pairs of rafters composing an interlaced wheel (the so-called “rueda de lazo”). Such a wheel constituted the basis module of any geometric motif.