Due to new energy code requirements, continuous insulation (CI) has become a critical component in many framed wall assemblies. One of the big challenges the new CI requirement presents is how to address thermal bridging. Different CI guidelines, such as the 2015 International Residential Code (IRC), the 2015 International Energy Conservation Code (IECC) and ASHRAE 90.1, along with a growing list of product choices complicates the issue, especially for builders unfamiliar with CI.
Green building consultant Carl Seville of SK Collaborative of Decatur, Ga. says: “The 2015 IECC requires CI for thermal and moisture management in exterior wall cavities using the prescriptive path in climate zones 6 and above. In a typical wood-framed wall with exterior CI, thermal bridging occurs at each stud, plate, and header, reducing the effective overall R-value of the wall well below the rated value of the cavity insulation. CI eliminates thermal bridging by improving the overall efficiency of the wall higher than the rated value of the cavity insulation.”
All-In-One Envelope Sheathing
Today a growing number of builders have identified a CI method that helps streamline the house wrapping process while solving thermal bridging in a single structural system.
The all-in-one structural panel system, called ZIP System R-Sheathing, consists of a water-resistive barrier and polyisocyanurate foam insulation layer manufactured onto the engineered wood panel that’s sealed with a high-performance acrylic adhesive tape system. The multi-layer wall system is engineered to save construction steps by combining weather, air, and heat resistance in the exterior envelope with enhanced drainage plane properties.
Code Compliant
ICC-ES Report, ESR-3373, verifies the sheathing system’s code compliance as a structural panel with integrated moisture, air, and thermal protection. Insulation performance can be modulated through a variety of panel thicknesses, ranging from 1-inch (R-value 3.6) to 2-1/2 inches (R-value 12.6). The report also details the product’s capability in resisting transverse and lateral loadings. These design values are also verified in ER-0482 for high seismic controlled regions. ZIP System R-sheathing can be used in intermittent braced wall panel construction under the 2015, 2012 and 2009 IRC and engineered lateral shear resistance designs under the 2015, 2012 and 2009 IBC.
Builder response to ZIP System R-Sheathing method has been positive. Andrew Johnson, co-founder of Jadee Construction, Arkansas’ only full-service construction and restoration contractor, says “You apply the tape and you’re done. It’s very simple and easy.”
Faster Installation
Eliminating the usual sequence in the exterior wall assembly steps can be helpful to builders looking for ways to cut construction time.
Seville says the system “… is significantly simpler and less costly than installing multiple layers of OSB and foam to achieve the same results. Eliminating a separate weather barrier also reduces installation costs.”
