Installing A Metal Roof Over Purlins

How to install metal roof purlins step 1.

Installing a metal roof over purlins.

Work up from the initial row starting at the lower corner in a diagonal pattern staggering the shingles to prevent gaps. Lay the first purlin at the ridge of. This is by far the most common way to install a metal roof. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.

It should overlap the edge of the gutter if you have them. 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. In this installation the vapor barrier is installed on the side of the insulation nearest the interior of the building. Lay the starter row of metal shingles at the drip edge and affix to the roof with metal roofing nails.

The most common method employed is laying the purlin flat typically a 2 4 and nailing to the truss with two 20d galvanized ring shank nails. Purlins are non pressure treated 1 x 4 x 12 lumber that is installed on to the roof in a specific layout pattern and screw pattern. This method is used for trusses designed to be closer together from 2 on center up to a maximum of 5 on center. As long as the plywood under the shingle roof is in good condition this way can provide many benefits.

Most metal shingles will be attached to the roof using metal shingle. Run a tape measure from end to end along the rafters of the roof to determine how many purlins will be needed. Snap a chalk line horizontally across the roof two feet down from the top. Set the second.

Use your 1 1 4 in 3 2 cm nails to secure the flashing to the subroof. You need to check the installation instructions from the manufacturer depending on whether the purlins firring strips are 1x or 2x material and how wide thickness metal gage of roofing steel or aluminum type of seams design wind and snow loading whether designed to be walked on or not etc i have seen it vary from as little as 4 inches clear gap between firring strips on lightweight aluminum to as much as 4 feet on very heavy gage steel standing seam roofing commonly around 1 2.