Insulating A Roof With Rigid Foam

Insulated roof assemblies can be vented or unvented.

Insulating a roof with rigid foam.

Install rigid insulation board in multiple layers with joints offset vertically and horizontally between adjacent layers. Rigid insulation layers exterior to existing roof sheathing must provide sufficient thermal insulation r value to control condensation risk see climate specific guidance. A continuous layer of rigid foam insulation in wall and roof assemblies leads to lower energy consumption an environmental plus to be sure. Start at the bottom of the roof and place the first piece of rigid foam insulation against the metal flashing starting at the center line.

It can be applied on the roof floor and walls and it s most widely used in structural insulated panels and insulated concrete forms. Eps is also the most inexpensive of the three types of rigid foam insulation while also meeting the required building and energy codes. Rigid foam boards come in different material compositions varying thicknesses and different insulating r value properties. There are lots of different ways to insulate this type of roof but one of the best methods calls for the installation of rigid foam insulation above the roof sheathing.

But one thing that some builders don t like is the high global warming potential of some blowing agents used to make the foam. 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. There are at least two good reasons why this approach makes more sense than installing the insulation under the roof sheathing.