Insulating A Roof With Rigid Foam

Rigid insulation layers exterior to existing roof sheathing must provide sufficient thermal insulation r value to control condensation risk see climate specific guidance.

Insulating a roof with rigid foam.

A continuous layer of rigid foam insulation in wall and roof assemblies leads to lower energy consumption an environmental plus to be sure. Nail it around the edges with roofing nails. 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.

Eps is by far the most versatile of the three rigid insulation options. Install rigid insulation board in multiple layers with joints offset vertically and horizontally between adjacent layers. But one thing that some builders don t like is the high global warming potential of some blowing agents used to make the foam. It can be applied on the roof floor and walls and it s most widely used in structural insulated panels and insulated concrete forms.

Insulated roof assemblies can be vented or unvented. 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. 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.