Rigid Insulation At Unvented Roof

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.

Rigid insulation at unvented roof.

Figure 3 shows the potential for condensation of an unvented roof assembly in houston tx. Houston tx is located in a hot humid climate region. We re big fans of fine homebuilding. Senior engineer manager at icynene john broniek makes the case for the unvented attic assembly and why insulating the underside of the roof makes sense.

We agree that avoiding sheathing rot is critical and that air permeable insulation such as fiberglass or cellulose cannot be used alone. This section outlines the conditions for unvented attic roof assemblies. Insulating unvented roof assemblies. Ratio of r value between rigid insulation and batt insulation is climate dependent.

In the most recent issue of fine homebuilding martin holladay wrote a piece on insulating unvented roof assemblies. If you don t want to use sips or nailbase read this article tolearn the four basic approaches to insulating unvented roof assemblies. Rigid insulation used to control condensing surface temperatures rigid insulation installed above roof deck.