Description
A typical roof penetration trimmer detail for steel-purlin roofs, drawn in plan at 1:10, showing how an opening for a duct, flue or rooflight is framed without weakening the roof structure. Short trimmer members matched to the main purlin size are set across the void and connected back to the run-through purlins with general-purpose brackets, and the note requires the penetration to be positioned so no more than one main purlin is cut.
It is the standard way to trim around a service penetration in a portal-frame or cold-formed steel roof, and this annotated detail gives you a clean version to trace or paste into your structural and roofing drawings, then size the trimmers and brackets to suit the purlin section.
See also the roof sheeting expansion joint and more in the structural details and steel categories. A free AutoCAD DWG download.
