Rigid Foam Board Under Metal Roof

Insulating a metal shed roof with rigid foam can be done one of three ways by laying the board prior to applying the roof by removing the existing roof and installing new foam board or by insulating the existing metal roof from the inside.

Rigid foam board under metal roof.

Use rigid foam insulation to cover wider spans of roof sheathing between joists. It can lie down perfectly under the metal roofing without having to deal with the hassle. Insulating with spray foam insulation. Rigid foam boards come in different material compositions varying thicknesses and different insulating r value properties.

It is not the normal insulation type that can be rolled up. Spray foam generally outperforms batt and blanket but loose fill and rigid board are good options too. You can always install this foam on the inside and outside of the sheath. Rigid board made from fiberglass would be the best option for roofs and basements as the high insulation rating allows it to insulate the home better than say loose fill or batt and blanket.

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. Install it anywhere from the roof to the foundation. Avoids nails or screws which could penetrate the metal roof and cause leaks. It can be touted that foam batting material is the best one to pair with metal roof insulation.

Cut each sheet to the desired size using a utility knife then fasten it in place using staples or adhesive. You can even place it under the foundation slab. Fiberglass is also one of the preferred materials for metal and steel buildings and homes.