Understanding Roof Ridge Sagging
Many homes have sagging roof ridges, such as this bar room of a local winery we had the privilege to inspect. This article explain some of the causes of sag in rafter roof structures.The Basics of a Rafter RoofThe basic structure is the triangle formed by the rafters which attach to the ridge board at the top and to the ceiling joists at the bottom. Triangles are the building blocks of all roof structures. To limit the rafters bending from the load on them, collar ties are added. They form a smaller triangle within the larger one. Collar ties are in the upper third of the rafter span, and are 1″x4″ lumber.Not shown in these diagrams, but there can also be rafter ties which are the same concept. Those go in the lower third of the rafter span and are 2″x4″ lumber. There is also a practical limit to the span … Continued