ABSTRACT
The roofing of buildings in which a vaulted or domed ceiling projects above the level of the wall plate presents a structural problem because a continuous tie beam cannot be used. British and American carpenters adopted quite different solutions to this problem. In America much of the building was in wood, and the carpenters were often faced with new problems—either problems that had not occurred in Europe or simply problems for which the particular builder knew no solution. The structural problem became greater when the forces were concentrated through purlins and their supporting frames. It should be clear, therefore, that as the roof pitch becomes shallower, the problem of restraining the feet of principal rafters becomes greater. Naturally, a larger span means a larger weight of roofing, which also increases the problem. The king post and the two parts of the tie could be joined together more easily if they were all made of wrought iron bar.
