Timber Roof Purlins

Purlin is a well known material in the field of architecture structural building or structural engineering.

Timber roof purlins.

Purlins are a series of horizontal timbers laid across or connected to as depicted above the principal rafters and support the roof covering typically 2 6 tongue and groove boards conventional or structural insulated panels sips and roofing. Purlins are installed horizontally under metal roofs. Purlins are 2 by 4 feet and are installed much like metal roofing. The purlins are the large beams perpendicular to the rafters.

This is a very traditional concept in heavy timber roof framing. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. Under purlins were typically propped off internal walls. There is an available purlin for every type of roofing material including purlin span for metal roof which is the most common material type to use this item.

From this shot it appears that there are three purlins on either side of the roof. Do all roofing projects require purlins. The rafters are the beams of wood angled upward from the ground. In lightweight timber roof construction under purlins were used to support rafters over longer spans than the rafters alone could span.

They meet at the top of the gable at a ridge beam which has extra bracing to attach it to the rafters. It is a horizontal bar that used to support building at the roof structurally.