Modern metal roofs are expected to last 30 years or longer.
Roof system no purlins.
Purlins traditionally support the roof deck cladding sheeting and are in turn supported by the principal rafters steel beams etc.
The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.
We do recommend it however.
In the past the majority of roof structures were of wooden construction but over the past 15 to 20 years there has been a vast shift away from wood to metal mainly steel roof construction.
While metal roofing doesn t require plywood underlayment there are circumstances in which you may wish to install plywood to anticipate future roofing needs or to offer additional soundproofing.
A common arrangement is a rafter and purlin system which combines purlins and rafters.
I am getting two different stories from contractors regarding purlins v s.
I have the option of installing the new roof directly to the existing deck or installing new decking if need be or installing 1x4 purlins 2 ft.
Standard gage are generally used for roofing.
Roof hugger retrofit sub purlins are zee shaped structural members that are typically 10 to 12 feet in length.
Onto the current decking and then installing the new roof to those.
When channels are used the ridge purlin is placed as close to the peak of the truss as possible in order to shorten the connection to the purlin on the opposite side of the centerline.
Besides providing support for the roof rafters and purlins add to the interior beauty so you often see log purlins and rafters that match the wall logs.
For new construction florida building code does not require the use of a purlin system and some profiles like our tcm loc panel does not require use of purlins.
They are made from 16 ga 0 060 min 50 ksi structural grade g 90 galvanized steel and specifically notched to fit over the ribs of the existing metal roof panels.
