Roofs with a higher weight may not require as much support as those with lighter weights. I assume this has been done many times before and I would like to avoid reinventing the wheel. A standard metal roof has a spacing of four to six feet for purlins. Architect suggested bearing walls at 4'oc cut down to the deck but there would still be point loads at each joist and uplift connections to deal with. A purlin is the name given to one of the horizontal metal bars that support the load of the roof deck. LAST REVISION DATE: 07/24/19 BY: AAJ CHK: JWS. 40ft x 12 480 24 on-center 20 rafters + 1 21 rafters per side x 2 42 rafters. Standard Purlin Spacing Standard Purlin Spacing (Gable Building) Standard Purlin Spacing (Single Slope Building) Standard Girt Spacing. You’ll get the number of rafters needed for your roof. After getting the answer, add 1 for the ‘0’ rafter and multiply it by 2.

Lots of little pieces and cutting holes through the deck to weld the columns down for up lift. If you’ve got a roof over your head, it’s partly thanks to purlins. 40ft x 12 480 (length in inches) 24 on-center 20 rafters. Steel roof panels serve as an environmental barrier as well as providing restraint to the supporting purlins. Figure 1.1 Typical Metal Building Framing. I have considered running beams perpendicular to the joists at 4' oc with stub columns down to the joists. 1.1 shows coldFigure-formed steel roof framing for a typical metal building. The existing structure is adequate for the loads. They give added support to the roof and also provide a nailing surface for the end panels and drip edge. Purlins are 2 by 4 feet and are installed much like metal roofing. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. In this case, providing a structure over the existing structure seems like overkill. Standard Details for Metal Roofing & Siding Post Frame and Residential Structures Distributed by: BEST MATERIALS ® Ph: 80, 60 Fax: 60 Email: . Purlins are installed horizontally under metal roofs. On past projects with shorter spans and bearing walls, I have used light gauge trusses at 8' oc and hat type purlins at 4' oc or so to support the standing seam roof. Narrow rib metal deck with 5' of insulation and a BUR. Joists span 45', are spaced 4' oc and have panel points about 4' oc. Tighten a washer and nut over the end of each bolt. When all girders are tacked in place, drill two 1/2 inch holes completely through the girders and posts at each connection and secure each corner assembly with two 1/2 inch lag bolts. The slope of new roof would be parallel to the joists. Fasten each corner assembly with two 1/2 lag bolts, washers, and nuts.

The owner and architect want to place a standing seam metal roof over an existing conventional bar joist and metal deck roof system.

Rafterpurlin spacing slanted metal roof