Q235B, etc. Standard Durable Construction House Steel Z Purlin Bracket

The primary advantage of Z Purlins is their Z-shape profile, which allows them to overlap (splice) at supports, creating a stronger, continuous span ideal for long-span roofing. Z purlins are stronger when oriented correctly (one flange up, one down). C Purlins are typically used for wall girts or shorter spans where overlapping is not required.

HDG provides a thick, durable zinc coating that protects the steel from rust, especially in humid, coastal, or industrial environments, lasting significantly longer than paint or pre-galvanized coatings. Unlike painted surfaces that can chip or scratch during installation, galvanized steel is self-healing at cut edges and requires virtually no maintenance.

These numbers refer to the cross-sectional dimensions: 200 mm is the web height (vertical height of the beam), 75 mm is the flange width (horizontal width of the top/bottom lips), 20 mm is the lip size (length of the small turned-up edge for rigidity), and 2.5 mm is the material thickness.

While they are primarily designed for roofing due to their overlapping strength, Z Purlins can be used for walls. However, C Purlins are generally preferred for walls (girts) because they are easier to install without the need for complex overlapping at joints.

Z Purlins are fixed to the main rafters using bolts and cleats (connection plates). To join two pieces together to achieve a long span, you must use splice plates at the overlap point. This ensures the structural integrity of the connection.