Purlin Roof Framing Diagram

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.

Purlin roof framing diagram. When a tie beam joins the feet of principal rafters the result is a triangle a rigid struc tural shape. There are many types of roof trusses as wall as many types of roofs more types than there are parts. Shed roof framing process explained step by step instructions. 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. The fascia board is the bottom plate and the ridge board the top plate. The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed. Figure 2 2 roof framing terms.

Stick to the basics of simplified design and use dimensions that don t generate waste. In wide structures rafters are often supported by purlin. This article and series of illustrated diagrams shows you all the parts of a basic roof truss king truss and queen truss. Component w sinθ in the plane of the sheathing.

They meet at the top of the gable at a ridge beam which has extra bracing to attach it to the rafters. 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. Keep it simple and remember. The rafters are the beams of wood angled upward from the ground.

Where the tie beam joins the wall framing we have the tying joint. The roof truss structure and design is integral to roof structural integrity and shape. This view is from the inside of the building below the roof. For a sloped roof the components of the gravity load are divided into a normal.

Outward thrust of the roof planes. 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. A view of a roof using common purlin framing. Framing a shed roof is similar to framing a wall.

Purlins are dimensional lumber that are fastened to the top chord of trusses connecting them together for bracing purposes. Component w cosθ perpendicular to the plane of the sheathing and a downslope. Secondary framing is an important component of many pre engineered metal buildings.