Trimmer purlins are required when there are cut outs in roof so as to support the roof. No drawings will show the requirement of trimmer purlins.

Detailer must know where trimmer purlins are required and how to put them.

Generally trimmer purlins are run between purlins and connected with GP BRACKET.

But if trimmer purlins are around a concrete col then the purlins can be true bolted to concrete col