Metal Roof Installed Over Purlins

For many applications a layer of plywood underneath your metal roofing is an unnecessary expense.

Metal roof installed over purlins.

The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. Choosing to install a metal roof this way can save you some dough and garner all of the benefits of a metal roof in the humid climate of florida. I was driving by a new building being constructed and it has wood trusses with 2x4 horizontal purlins looks to be about 2 oc spacing on the trusses. The flashing should overlap the edge of the roof by one inch to help direct water.

I have been playing around with the ribbed metal roof but pricing is pretty high over shingles obviously. It helps direct water away from the meeting points and keeps the roofing dry. The second way to install a metal roof over a shingle roof is with the use of purlins or battens. They give added support to the roof and also provide a nailing surface for the end panels and drip edge.

Bend the flashing into a v shape to fit over the top roof ridge and the corners where the panels meet. Doesn t provide the flattest surface for the metal roofing to be installed over each course of shingles is about a 1 8 higher than the course just below it. They then installed the metal directly to that. Purlins are 2 by 4 feet and are installed much like metal roofing.

Metal roofing panels rated for architectural use attached to purlins horizontal pieces of wood or metal fastened to roofing trusses are structurally sound when installed according to your roofing manufacturer s instructions and local building codes. Metal roof purlins are installed horizontally under metal roofs. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. The purlins are screwed or nailed down to the roof deck depending on how the metal roofing manufacture has testing for their roofing panels and then the metal is installed to the purlins.

Flashing is metal trim that fits over joints where two sections of roof meet.