Rigid Foam Under Metal Roof On Purlins

Will that be a concern with metal roofing.

Rigid foam under metal roof on purlins.

Use rigid foam insulation to cover wider spans of roof sheathing between joists. 4 of polyiso under 4 of eps all above the original roof sheathing. Basically speaking ignoring sub insulated roofs which are a special case with rigid foam board insulation directly under the metal roofing the roofing needs proper support to be able to handle snow ice loads wind loads and walking on during installation cleaning and maintenance. In this insulation approach rigid foam insulation board is used to achieve the sought after energy performance.

Avoids nails or screws which could penetrate the metal roof and cause leaks. Plywood sheathing then roofing felt than 1 5 rigid foam metal roofing. Then a second layer of plywood sheathing and asphalt shingles following the steps explained in this article. 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.

Purlins are 2 by 4 feet and are installed much like metal roofing. It is possible to insulate from below as you suggest with rigid polystyrene insulation. I know that most roofs have ventilation under them to prevent overheating of the roofing material. This is different from the normal roll up type of insulation as it comes in panels rather than paper covered fiberglass.

This foam can be used on either the outside or the inside of the sheathing. Cut each sheet to the desired size using a utility knife then fasten it in place using staples or adhesive. First nail 1x2s to the rafter sides up against the roof strapping. They give added support to the roof and also provide a nailing surface for the end panels and drip edge.

Commonly these use metal deck panels over the roof structure thus supporting the insulation and a vapor retardant material on top of the deck. I have a 90 year old stone cottage in portland oregon. The best material for use with metal roof insulation is in the form of foam batting. Insulating with spray foam insulation.

They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top. I am getting ready to put a metal roof on my house it presently has 1 layer of shingles on a 6 12 pitch and iam in florida i am think of putting r foil under 1 x 4s battens or the styrofoam boards between the battens and also a solar attic fan w elec option and the metal will be a light color from douglas metal roofing does this sound like a. Metal roof purlins are installed horizontally under metal roofs.