Design Guide for Rural Northern Ireland
Traditional Qualities: Plan Form
The plan form of rural buildings arose from the method of roof construction. Because of the limited length of available roofing timbers the span of the roof was restricted, so that buildings had just a single-room depth. A series of rooms then produced the familiar linear plan form.
In later years the use of imported timber and the development of the purlin roof led to wider spans, giving a two room depth to dwellings. This produced the square plan form characteristic of the grander houses.