Timber Roof Purlins

Do all roofing projects require purlins.

Timber roof purlins.

It is a horizontal bar that used to support building at the roof structurally. 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 non pressure treated 1 x 4 x 12 lumber that is installed on to the roof in a specific layout pattern and screw pattern. They give added support to the roof and also provide a nailing surface for the end panels and drip edge.

The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. The rafters are the beams of wood angled upward from the ground. Under purlins were typically propped off internal walls. This is a very traditional concept in heavy timber roof framing.

The purlins are the large beams perpendicular to the rafters. They meet at the top of the gable at a ridge beam which has extra bracing to attach it to the rafters. From this shot it appears that there are three purlins on either side of the roof. Purlins are installed horizontally under metal roofs.

They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. 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.