Rigid Foam Under Metal Roof On Purlins

Purlins are 2 by 4 feet and are installed much like metal roofing.

Rigid foam under metal roof on purlins. This foam can be used on either the outside or the inside of the sheathing. I have a 90 year old stone cottage in portland oregon. 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. Will that be a concern with metal roofing.

I know that most roofs have ventilation under them to prevent overheating of the roofing material. 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. 4 of polyiso under 4 of eps all above the original roof sheathing. They give added support to the roof and also provide a nailing surface for the end panels and drip edge.

This is different from the normal roll up type of insulation as it comes in panels rather than paper covered fiberglass. Avoids nails or screws which could penetrate the metal roof and cause leaks. 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. Use rigid foam insulation to cover wider spans of roof sheathing between joists.

Insulating with spray foam insulation. 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. They are installed on top of the roof rafters with a felt underlayment or vapor barrier installed on top.

The best material for use with metal roof insulation is in the form of foam batting. We live in zone 5 suburb of chicago and are hopefully about to put rigid foam above the roof sheathing on just the northeast roof portion of our roof. In this insulation approach rigid foam insulation board is used to achieve the sought after energy performance. Plywood sheathing then roofing felt than 1 5 rigid foam metal roofing.

This will provide an air space above the foam insulation to improve ventilation on the underside of the metal roofing. Cut each sheet to the desired size using a utility knife then fasten it in place using staples or adhesive. Commonly these use metal deck panels over the roof structure thus supporting the insulation and a vapor retardant material on top of the deck.