Rigid Insulation At Unvented Roof

We agree that avoiding sheathing rot is critical and that air permeable insulation such as fiberglass or cellulose cannot be used alone.

Rigid insulation at unvented roof.

We re big fans of fine homebuilding. Figure 3 shows the potential for condensation of an unvented roof assembly in houston tx. 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. If you don t want to use sips or nailbase read this article tolearn the four basic approaches to insulating unvented roof assemblies.

Houston tx is located in a hot humid climate region. Ratio of r value between rigid insulation and batt insulation is climate dependent. Unvented roof assemblies should be insulated either with air impermeable insulation rigid foam or spray polyurethane foam or with a combination of foam and air permeable insulation. Foam free don t stay stuck in the sci finightmare of foam foam foam.

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. Rigid insulation used to control condensing surface temperatures rigid insulation installed above roof deck. In the most recent issue of fine homebuilding martin holladay wrote a piece on insulating unvented roof assemblies.