Purlins & Structural

A C section has both flanges facing the same way, so it sits neatly on its own and is the usual choice for single spans, side rails and end bays. A Z section has flanges facing opposite ways, which lets consecutive purlins overlap at the supports — that overlap makes the run behave as a continuous beam and lets it span further for the same weight of steel.

If in doubt on a multi-bay building, Z sections with sleeved or lapped joints are normally the more efficient answer.

It comes from the span, the spacing between purlins, and the roof loading for the site. Guessing is expensive in both directions — too light and it deflects, too heavy and you have paid for steel you did not need.

Send us the span, the centres you are planning and what the roof build-up is, and we will size it.

Yes, and they should be ordered with the purlins rather than afterwards, because the cleat has to suit both the purlin section and the steelwork it is bolting to.

Yes — they are cut and punched to order, so the holes land where your steelwork actually is. Send the setting-out and we will punch to it.