How Close Do You Install Perlins Under A Metal Roof

You will also need to install purlins around penetrations such as plumbing pipes electrical pipes and skylights among others.

How close do you install perlins under a metal roof.

Step 1 run a tape measure from end to end along the rafters of the roof to determine how many purlins will be needed for installation. He won t do it unless i put on plywood as a base he also recommended ice and water underlayment. Purlins need to follow the sides edges of the roof it is important to note that in addition to the proper spacing and doubling of purlins the valleys it is essential to include purlins along the entire perimeter of the roof. It needs to be replaced due to leaks and one contractor the one i d really like to hire refuses to put the new metal roof on just purlins.

They give added support to the roof and also provide a nailing surface for the end panels and drip edge. I have an existing steel roof presently just on purlins. Purlins are 2 by 4 feet and are installed much like metal roofing. When using plywood nail it directly to the purlins and screw the metal roofing panels through the plywood into the purlins as instructed by the manufacturer.

If the roof has no roen decking and only one layer of roofing you can usually apply an insulating barrier 1 4 foam core insulation and just apply right over the existing roof. Do i need the plywood base. Too high a snow load means the purlins fail regardless of how close together you put them because a 2 4 or 2 6 flat can only span a certain distance between trusses as snow loads increase. Place the first screw about 7 inches from the bottom and each subsequent screw about 18 to 24 inches apart along the vertical run.

Twenty four inches is a common spacing of furring strips for a metal roof. You can easily go through several sheets of insulation and know that they are secure. There are two ways to do this put in firring nailing though nails are not used any more for this strips or purlins in steel frame construction on the roof to support it or place the metal roofing directly on a flat surface like foam insulation board or the roof sheathing with roof water barrier in the correct position in the layer. The easiest and by far the quickest way to install metal roof insulation is with 1 inch staples.

Correctly measure the spacing of furring strips for a metal roof to further decrease condensation. Install the roofing screws vertically along each rib in the panel. The washer under the screw head should seal to the surface of the panel without bulging or shifting. Another benefit of using staples is that they do not make a large hole when penetrating into the sheathing.

In this installation the vapor barrier is installed on the side of the insulation nearest the interior of the building.