Installing A Metal Roof Over Purlins

Run a tape measure from end to end along the rafters of the roof to determine how many purlins will be needed.

Installing a metal roof over purlins.

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. In this installation the vapor barrier is installed on the side of the insulation nearest the interior of the building. How to install metal roof purlins step 1. This is by far the most common way to install a metal roof.

This method is used for trusses designed to be closer together from 2 on center up to a maximum of 5 on center. 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. Snap a chalk line horizontally across the roof two feet down from the top.

Lay the starter row of metal shingles at the drip edge and affix to the roof with metal roofing nails. Most metal shingles will be attached to the roof using metal shingle. The topic we want to discuss today is the purlin installation. 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.

Lay the first purlin at the ridge of. It should overlap the edge of the gutter if you have them. 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. 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.

The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to. As long as the plywood under the shingle roof is in good condition this way can provide many benefits.