Purlin Roof Framing Diagram

In architecture or structural engineering or building a purlin or purline is a horizontal structural member in a roof.

Purlin roof framing diagram.

The purlin are ultimately used to fasten the roof steel providing a diaphragm effect along with the siding when properly engineered and installed. Stick to the basics of simplified design and use dimensions that don t generate waste. The roof truss structure and design is integral to roof structural integrity and shape. They meet at the top of the gable at a ridge beam which has extra bracing to attach it to the rafters.

For a sloped roof the components of the gravity load are divided into a normal. 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. Line length is the hyptenuse of the triangle whose. Tying joints are usually the only connections in a frame that must resist tension.

Outward thrust of the roof planes. About the base of the purlin based on the free body diagram shown in figure 3. Component w sinθ in the plane of the sheathing. 1 8 pitch is given so 24 x 1 8 equals 3 or unit of rise in inches.

Keep it simple and remember. Framing a shed roof is similar to framing a wall. There are many types of roof trusses as wall as many types of roofs more types than there are parts. Purlins are dimensional lumber that are fastened to the top chord of trusses connecting them together for bracing purposes.

A view of a roof using common purlin framing. The fascia board is the bottom plate and the ridge board the top plate. When a tie beam joins the feet of principal rafters the result is a triangle a rigid struc tural shape. 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. Secondary framing is an important component of many pre engineered metal buildings. 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. 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.

Shed roof framing process explained step by step instructions. Component w cosθ perpendicular to the plane of the sheathing and a downslope. Figure 2 2 roof framing terms.