The Earliest Development of Roof Construction in Leiden (NL)

Intensive building-historical research in the Dutch city of Leiden makes a comparative study on fourteenth, fifteenth and sixteenth century roof constructions possible. The earliest constructions are rafter roofs supported by trusses. No changes are discernible in the basic design until in the 16th century. A new element is a triangular truss that supports a ridge purlin. This modernization was presumably the result of a transition to heavier roofing materials.More developments are progression and simplification on a constructive level. The use of tenon joints diminishes and the joints become increasingly butted and nailed. The carpenter's craft can be derived from the assembly marks. The dated examples make a development apparent. Dendrochronological research reveals that the timber came from West Germany. Felled timber was transported by raft via the rivers, and came to Leiden as traded timber. Raft holes are the witnesses to this trade.