Rigid Foam Under Metal Roof On Purlins

If you want to be sure talk to your roofer or the manufacturer of the roofing panels.

Rigid foam under metal roof on purlins.

This is different from the normal roll up type of insulation as it comes in panels rather than paper covered fiberglass. First nail 1x2s to the rafter sides up against the roof strapping. Rigid board composite systems. As far as i know standing seam metal roofing can t be installed on rigid foam.

Use rigid foam insulation to cover wider spans of roof sheathing between joists. I would seal the eps against the purlins with a high grade permanently flexible caulk or spray foam insulation. The best material for use with metal roof insulation is in the form of foam batting. 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.

The rigid board material costs roughly 23 cents per square foot. Further insulation may be added by the use of high r foam boards placed beneath the purlins. Avoids nails or screws which could penetrate the metal roof and cause leaks. Oh i forgot to mention purlins are best placed 24 inches on center to fit with the most common insulation width and insulation between purlins should be unfaced.

It will help you to eliminate problems that may come when the house becomes extremely cold in the winter and terribly hot in the summer. It is possible to insulate from below as you suggest with rigid polystyrene insulation. Insulating with spray foam insulation. Cut each sheet to the desired size using a utility knife then fasten it in place using staples or adhesive.

This will provide an air space above the foam insulation to improve ventilation on the underside of the metal roofing. This foam can be used on either the outside or the inside of the sheathing. However code requires them to be covered with a fire barrier on the inhabited side. Polyurethane spray foam metal roof insulation in order to add moisture barrier under metal roof you can spray the undersides of the roof by using a thick layer of polyurethane spray foam.

The solution i have in mind is to cut 2 foot wide strips of 1 2 thick foil poly faced eps to fit between the purlins 1 2 below the metal roofing.