Purlin Roof Framing Diagram

Shed roof framing process explained step by step instructions.

Purlin roof framing diagram.

A view of a roof using common purlin framing. Secondary framing is an important component of many pre engineered metal buildings. The roof truss structure and design is integral to roof structural integrity and shape. Component w sinθ in the plane of the sheathing.

This view is from the inside of the building below the roof. If the unit of rise in inches is 3 then the cut is the unit of rise and the unit of run 12 inches or 3 12. Purlins are dimensional lumber that are fastened to the top chord of trusses connecting them together for bracing purposes. This article and series of illustrated diagrams shows you all the parts of a basic roof truss king truss and queen truss.

About the base of the purlin based on the free body diagram shown in figure 3. 1 8 pitch is given so 24 x 1 8 equals 3 or unit of rise in inches. Keep it simple and remember. There are many types of roof trusses as wall as many types of roofs more types than there are parts.

They meet at the top of the gable at a ridge beam which has extra bracing to attach it to the rafters. In architecture or structural engineering or building a purlin or purline is a horizontal structural member in a roof. Also referred to as secondary structurals this type of framing runs in between primary framing elements creating a structure within a structure much like cross beams in a wooden building. Tying joints are usually the only connections in a frame that must resist tension.

The fascia board is the bottom plate and the ridge board the top plate. Where the tie beam joins the wall framing we have the tying joint. Outward thrust of the roof planes. Framing a shed roof is similar to framing a wall.

The rafters are the beams of wood angled upward from the ground. Line length is the hyptenuse of the triangle whose. Stick to the basics of simplified design and use dimensions that don t generate waste. In wide structures rafters are often supported by purlin.

Purlins support the loads from the roof deck or sheathing and are supported by the principal rafters and or the building walls steel beams etc. Figure 2 2 roof framing terms. Component w cosθ perpendicular to the plane of the sheathing and a downslope.