Metal Roof Joist Spacing

Typically pole barn style buildings in my area have bays distance between trusses of 5 feet to 12 depending on pitch insulation and height.

Metal roof joist spacing.

The same concept holds true for roof trusses. If there are gutters installed on the eaves the eave flashing should be installed to overhang the lip of the gutter by about 1 2 inch. A metal roof must also allow for some overlap on each side of the panels which will reduce the effective width of the panel. Place corner pieces where panels will meet bends at the edge of the roofing.

Correctly measure the spacing of furring strips for a metal roof to further decrease condensation. The tables below give maximum spans for rafters and beams. The substructure to which the metal panels are fastened must be properly spaced and sufficiently thick to provide a roof or wall system able to meet required design loads. In areas with mild climates patio roofs are generally designed for loads of 30 psf pounds per square foot.

Steel roof panel systems west conshohocken pa. Use 1 1 4 inch nails to cover the outline of the roof with strips of metal eave flashing also called edging. Astm e1592 05 2017 standard test method for structural performance of sheet metal roof and siding systems by uniform static air pressure difference west conshohocken pa. Truss spacing for metal roof.

A roof joist is always spaced no more than 16 inches apart from another roof joist. A 2 nominal lumber thickness provides the maximum pullout values for both screws and nails when the fasteners penetrate a minimum of 1 into the wood. Rafter spacing is based on the width of the metal roofing panels. So the space between rafters can be greater without reducing the maximum span.

For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2. If the roof is not completely square you can decrease the space between joists but never increase the space. For heavy roofs or in areas with substantial snowfall or winds call your local building department for code requirements. Wider panels allow for greater spacing between rafters.

Astm e1646 95 2011 standard test method for water penetration of. In other words you would space a roof joist 15 inches apart from another roof joist but never 17 inches apart. If purlins are laying flat on top of the truss 5 or 6 feet is the max on 2x4 s edge up can go to 12 feet or more. Common spacing for trusses on this type of building is often between 2 and 4 feet but trusses built with advanced designs may allow spacing as great as 8 or 12 feet.