The Knowledge of Carpenters from the Early Medieval Period to the Eighteenth Century in Setting Out Roofs and Buildings Without Geometry and Numerical Measurement

The question of how medieval carpenters set out their work is an under-investigated topic of research. Advanced craft knowledge is needed for a study of this kind and, in that regard, this article is written from a master craftsman’s point of view. Domestic medieval roofs have consistently common roof pitches of 48°, 52°, 55° 1 and 58°, and roofs were being pitched long before the early scholars brought knowledge from the ancient world to England in the mid-twelfth century. Moreover, it is unlikely that master carpenters and masons had access to this knowledge until the early to mid-thirteenth century, and equally unlikely that the domestic carpenter had any knowledge of geometry until the seventeenth or eighteenth century. Instead, this article argues that medieval carpenters used a simple method of setting out using cord, which would obviate the need for measurement and geometry and whose common divisions correspond to the common pitches found in medieval buildings. This article is on a subject of ongoing debate in which there are a range of views, and it is anticipated that a response will be published in due course.