How Close Do You Install Perlins Under A Metal Roof

Twenty four inches is a common spacing of furring strips for a metal roof.

How close do you install perlins under a metal roof. 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. You can easily go through several sheets of insulation and know that they are secure. The easiest and by far the quickest way to install metal roof insulation is with 1 inch staples. Applying right over the shingles will rub the back of the metal roof and eventually holes in the panels.

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. Install the roofing screws vertically along each rib in the panel. Place the first screw about 7 inches from the bottom and each subsequent screw about 18 to 24 inches apart along the vertical run. I have an existing steel roof presently just on purlins.

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. Secure the screws but do not overtighten. The washer under the screw head should seal to the surface of the panel without bulging or shifting. 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. 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. Correctly measure the spacing of furring strips for a metal roof to further decrease condensation. 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. The common 4 on center design is suitable for snow loads up to 60 for most applications. 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.

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