Roof Purlin Details

The use of purlins as opposed to closely spaced rafters is common in pre engineered metal building systems and both the ancient post and beam and newer pole building timber frame construction methodologies.

Roof purlin details.

Purlins girts and roof deck the substructure to which the metal panels are fastened must be properly spaced and sufficiently thick to provide a roof or wall system able to meet required design loads. Purlin plate principal purlin and common purlin. Bridging and purlin accessories are manufactured from steel with a minimum yield of 300 mpa and galvanised coating of z275 or zinc aluminium alloy az150 coating. With rafters it runs in perpendicular from the walls to the ridge while with purlins it runs to the ridge in parallel.

In a nutshell it s made up of a central vertical post called the king post two rafters meeting at the apex and a tie beam or the horizontal base. A 2 nominal lumber thickness provides the maximum pullout values for both screws and nails when the fasteners penetrate a. In traditional timber framing there are three basic types of purlin. It is often used in simple roof trusses such as in the shed porch and garage.

Minimum number of spans is 2 and the maximum span is 12 5m. The advantage is a reduced number. Purlin is a well known material in the field of architecture structural building or structural engineering. They are made from 16 ga 0 060 min 50 ksi structural grade g 90 galvanized steel and specifically notched to fit over the ribs of the existing metal roof panels.

Stramit purlins and girtsare manufactured from hi tensile g450 g500 or g550 galvanised steel with a minimum z350 galvanised coating 350g m2. In architecture or structural engineering or building a purlin or purline is a horizontal structural member in a roof. 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. Details on page 45 load tables on page 33 sleeved double span system sleeves are provided at all penultimate supports and are staggered at internal bays.

Purlins traditionally support the roof deck cladding sheeting and are in turn supported by the principal rafters steel beams etc. The king post roof truss is the simplest of the trusses because of its simple composition. It is a horizontal bar that used to support building at the roof structurally. Roof hugger retrofit sub purlins are zee shaped structural members that are typically 10 to 12 feet in length.

Using a combination of rafters and purlins is common. And roof pitches within the limitations given in this manual. In architecture structural engineering or building a purlin is any longitudinal horizontal structural member in a roof except a type of framing with what is called a crown plate.