Abstract: An energy-conserving roof structure for use in construction of low-slope fs comprising two layers of permeable insulation and a layer of non-permeable insulation sandwiched between a pair of water vapor impermeable layers. The non-permeable insulation layer is placed to provide channels through which water will flow to roof drains. Closeable vents are provided adjacent the roof drains for venting water and water vapor. When the vents are closed the water vapor impermeable layers form a water vapor impermeable envelope around the insulation layers. Auxiliary vents are provided for venting the insulation layers to the ambient atmosphere at locations remote from the roof drains. By opening the vents when low-humidity conditions are present and closing the vents when high-humidity conditions are present moisture in the insulation layer is kept to a minimum, thereby maintaining the insulation layers at their highest thermal efficiency.

Abstract: An energy-conserving roof structure for use in construction of low-slope roofs comprising two layers of permeable insulation and a layer of non-permeable insulation sandwiched between a pair of water vapor impermeable layers. The non-permeable insulation layer is placed to provide channels through which water will flow to roof drains. Closeable vents are provided adjacent the roof drains for venting water and water vapor. When the vents are closed the water vapor impermeable layers form a water vapor impermeable envelope around the insulation layers. Auxiliary vents are provided for venting the insulation layers to the ambient atmosphere at locations remote from the roof drains. By opening the vents when low-humidity conditions are present and closing the vents when high-humidity conditions are present moisture in the insulation layer is kept to a minimum, thereby maintaining the insulation layers at their highest thermal efficiency.