What type of insulation may be installed above the roof sheathing?

Installing insulation above the roof sheathing is an important practice to improve thermal performance and prevent heat loss. Insulation board is specifically designed for this purpose because it provides rigid support and can be installed directly on top of the roof sheathing, creating a continuous layer of insulation. This helps to minimize thermal bridging and improves the energy efficiency of the roof system.

Insulation board typically comes in various thicknesses and can often have protective facings that enhance moisture resistance, making it suitable for an exposed environment above the roof sheathing. Its rigidity also allows it to withstand various environmental conditions without significant deformation or settling.

Fiberglass rolls, while commonly used in other areas of a building, are not typically installed above sheathing due to their flexibility and potential for air gaps. They are better suited for installation between rafters or joists.

A vapor barrier’s primary function is to control moisture movement rather than provide thermal insulation, so it does not serve the same purpose as insulation board. Reflective foil is used in conjunction with other types of insulation to enhance thermal performance but is not installed directly above the roof sheathing and does not provide insulation on its own.

Therefore, insulation board is the most appropriate choice for installation above the roof sheathing, as it effectively maintains thermal