Installing A Metal Roof Over Purlins

This method is used for trusses designed to be closer together from 2 on center up to a maximum of 5 on center.

Installing a metal roof over purlins.

How to install metal roof purlins step 1. 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. 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. Lay the starter row of metal shingles at the drip edge and affix to the roof with metal roofing nails.

Lay the first purlin at the ridge of. 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. Use your 1 1 4 in 3 2 cm nails to secure the flashing to the subroof. Work up from the initial row starting at the lower corner in a diagonal pattern staggering the shingles to prevent gaps.

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. This is by far the most common way to install a metal roof. 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.

The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. 3 install 1x4 purlins down over the shingles before installing the metal roof the third way to install a metal roof over shingles is by applying 1x4 purlins over the shingle roof. 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.

The edging or eave flashing consists of metal strips that are used to cover the perimeter of the roof. It should overlap the edge of the gutter if you have them.