Rigid Insulation At Unvented Roof

Houston tx is located in a hot humid climate region.

Rigid insulation at unvented roof.

Insulating unvented roof assemblies. The quest for greater energy efficiency in buildings has led to increasing interest and need for insulation improvements in hvac equipment more airtight construction new materials and assemblies. In the most recent issue of fine homebuilding martin holladay wrote a piece on insulating unvented roof assemblies. We agree that avoiding sheathing rot is critical and that air permeable insulation such as fiberglass or cellulose cannot be used alone.

Note that table r806 4 indicates the amount of insulation above the roof deck or air impermeable insulation below the roof deck required for condensation control assuming minimum required total insulation as indicated in section n1102 building thermal envelope. Rigid insulation used to control condensing surface temperatures rigid insulation installed above roof deck. Foam free don t stay stuck in the sci finightmare of foam foam foam. Figure 3 shows the potential for condensation of an unvented roof assembly in houston tx.

Ratio of r value between rigid insulation and batt insulation is climate dependent. We re big fans of fine homebuilding. This section outlines the conditions for unvented attic roof assemblies.