What is Purlin Roof Construction?
Purlins are horizontal bars or beams that are used for structural support in the construction of a roof. They are supported either by the walls of the building or by rafters. Although they are usually used in metal roof constructions, they can sometimes be used to replace rafters fitted closely together in a wooden roof frame.
The purlins are designed to support the weight of the roof deck, which is the metal sheeting, plyboard, or wooden panels that are used to create the roof’s surface. They create a horizontal frame that is designed to completely support the weight of the roof deck of the building, no matter what material is used for the roof itself. They also help to ensure that the entire roof structure is more rigid and add mid-span support that enables you to create a wider building. They are installed under the metal roof horizontally, on top of the rafters with a vapour barrier or a felt underlayment installed on the top. Along with providing support for the roof, they provide a nailing surface for end panels and drip edges.
There are several different types of purlin. They are divided into categories that are based on their shape and the material from which they are made. Different purlins have different uses including structural support for floors or walls. Although solid wooden beams are sometimes used as purlins, the most common type used in roofing is made from thin steel.
Steel purlins are the most common choice since they are sturdy and reliable roofing material. Steel purlins are damp resistant and are not affected by mould, shrinking, or swelling in the way that wooden purlins might be. Regardless of the weather conditions that it is exposed to during the process of construction, a steel purlin will retain its original shape and strength. Steel purlins are also popular due to the fact that although they are very lightweight, they have a surprisingly high load-bearing capacity making them ideal for almost all roofing construction purposes.
Wooden purlins are less commonly used in roofing, although they are often the top choice for use with fibre cement sheeting since the wood and sheeting work well together to ensure that the room below is breathable. However, since they are made from wood, these purlins are more susceptible to problems like rot and mould. Moisture can add to the weight of the wooden purlins significantly, increasing the risk of sagging.