In any shed, purlins play a critical part in ensuring that your shed has the support required for it to remain structurally sound. A purlin is a horizontal beam or bar that is used in a shed that provides structural support to help support the weight of the roof, making purlins a key component of the secondary shed frame. Not only do purlins help to support the roof weight, but they also help to make the roof structure more rigid, which in turn helps to increase the resistance of your shed to excessive weather conditions.
There are 2 main types of purlins available C section and Z section, with both getting their names from the shape of the purlin. Ensuring that you select the right purlin type for your shed is essential to guarantee the structural integrity of your shed.
C Section Purlins
C section purlins are square c shaped purlins that are great for smaller-sized sheds. Each purlin has equally sized top and bottom flanges. Due to the c shape of the purlin, they can’t be lapped, meaning they can only be used for single spans and unlapped continuous spans.
Z Section Purlins
Z section purlins are purlins shaped similarly to the letter z that are great for sheds with large spans. They feature a broad and a narrow flange, allowing them to be lapped, which helps to increase the thickness resulting in higher load capacities. When rotated 180°, the purlins fit snugly together, which helps create an even stronger hold. The z shape of the purlin makes z sections purlins more flexible than c section purlins while also allowing for an increased spanning capability over the c section purlins.
While there is no right or wrong answer when it comes to the selection of your purlins, making an informed decision on which purlins are right for your shed type can help ensure your shed remains structurally sound.