ABSTRACT
Dutch roof construction belongs to a Flemish-Dutch group with common rafters supported by trusses. This has originated from the common rafter roof. For Leiden (West Netherlands), systematic documentation, including dendrochronological research, has made clear that medieval roof constructions consist of transverse (stacked) trusses, which support common rafters. From 1543 (d.) the constructions are provided with a ridge purlin, for stiffening of the ridge. By combining these data with roofing subsidies, it can be demonstrated that ridge purlin is the result of the transition from the flat ceramic tile to the new corrugated pantile. The structure of trusses does not change, but is supplemented with a ridge purlin on a ridge-truss. This application of a ridge purlin can (mistakenly) lead to the idea that this has originated from the purlin roof. The development makes it clear that the Flemish-Dutch construction is a development of the common rafter roof and is a separate variant.
