Insulate Metal Roof Over Purlins

The system of installing metal roofing over the trusses or over purlins is typical.

Insulate metal roof over purlins.

When fiberglass batts are installed in unvented bays the batts allow moist indoor air to reach the cold steel roofing or sheathing. Roof wall new install over purlins. 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. Factory pre cut white vinyl faced fiber glass blankets are placed in between the metal roof purlins and held in place by steel strapping called banding screwed to the bottom of the purlin.

Stand off roof clips are fastened to the top of the purlins using self drilling fasteners and the metal roof panels are attached to the stand off clip creating slightly more space above the purlin. It gets more complicated when you look at adding the foam into the equation. The most common material used for an insulating metal roof is fiberglass batts or glass mineral wool. This shop will be insulated but mostly unheated except when i m working in there say 10 hours a week.

Use prodex 48 inch fast action 72 inch 10m white rustic reflective bubble reflective or foil fiberglass vinyl. Do all roofing projects require purlins. As long as the plywood under the shingle roof is in good condition this way can provide many benefits. Both materials make a great physical barrier between the interior building and the metal roof.

The batts are located side to side on the rafter of the roof. You ve got the metal the foam and the interaction between them to consider. 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. The purpose of the purlins is to provide a solid foundation for the metal roofing panels and trim to be screwed to.

One of the more popular methods of placing metal roofing on a home is to lay down purlins across the existing shingles. Fiberglass batts or glass mineral wool metal roof insulation. I was planning to install directly over 2x4 purlins which are mostly already installed. A thermal spacer block is typically recommended depending on the stand off distance and the amount of insulation draped over the purlins.

We do recommend it however. Apply double sided tape on the top of purlins helps keep the insulation from blowing in the wind. I am installing ribbed metal panels over a singlt slope roof on a new workshop. In this case simply lay the insulation between the purlins.

Your roof purlin spacing can vary but 5 on center and 8 inches in depth is common which is the available insulating area. This is by far the most common way to install a metal roof.