 |
|
The Icynene applied to the roof in this attic is part of making it an air-tight, conditioned space.
|
Toronto, Ont./March 14, 2006—It became evident during the hurricane season of 2005 that homeowners and insurers could benefit from new construction techniques designed to increase a home's resistance to wind and water damage. The year 2005 holds the record for the number of named Atlantic storms (27), obliterating the previous record of 21 in 1933.
In October, Icynene Inc., manufacturer of The Icynene Insulation System, initiated a study of hurricane wind effects to evaluate improved insulating practices that can protect homes and their occupants from water and moisture damage resulting from high winds similar to those experienced last season. The study, conducted by The Alan G. Davenport Wind Engineering Group at the University of Western Ontario, used a model home with reduced air infiltration rates similar to the rates that would be achieved had the home been insulated with Icynene insulation/air barrier system.
The model was a gable-roof house with the attic and living space scaled to maintain similar volume ratios to that of a full-scale home. Two of the tests conducted measured the performance of two different insulation applications with the purpose of determining which treatment would deliver better performance in strong winds. Wind climate models for Chicago and Miami were used during the tests. In the first scenario, a typical vented attic design was tested. Tests showed that wind, and the laterally driven rainwater carried with it, entered the attic through the soffit vent assemblies. In real life, these conditions can lead to a flooded attic, an increased risk of mold growth and rotting building materials.
Building science expert Joe Lstiburek of Building Science Corp. studied rainwater performance of residential assemblies in Central Florida during the 2004 hurricanes. In his report, Lstiburek suggests that "soffit geometries are currently not designed to address extreme wind-driven rain exposures." Many experts, including Lstiburek, recommend an unvented, conditioned attic design in order to eliminate rainwater entry, which is the basis of Icynene Inc.'s second test: All of the soffit vents were sealed, creating an unvented sealed attic assembly. With this approach, the attic becomes part of the conditioned space.
Tests uncovered that sealing the soffits eliminated rainwater and moisture ingress into the attic, which helps prevent moisture damage to the insulation and ceiling materials. Similarly, Lstiburek's study found that "this technology [unvented conditioned attic construction] has significant advantages in the Florida climate with respect to rainwater control, energy conservation, moisture and humidity control, wind uplift and fire performance over standard attic roof technology."
Icynene Inc. is one of the first insulation manufacturers to invest in third-party wind tunnel testing of its product's performance in an unvented conditioned attic assembly. Icynene is also one of the few insulation products that are approved for use in this type of application. A unique material property of Icynene is its ability to create a complete air-seal, thereby reducing airflow and accompanying moisture in and out of the building envelope. Because of Icynene's proven performance in unvented conditioned attics, the product has been the insulation of choice for high-profile demonstration projects that feature this design.
The International Code Council (ICC) recently approved amendments to its International Energy Conservation Code (IECC) and International Residential Code (IRC) that approve unvented conditioned attic assemblies, stipulating that an air-impermeable insulation can be applied directly to the underside/interior of the structural roof deck. With 2005 resulting in record insured property losses—much of it attributed to water damage—it's time for trade professionals to consider an alternative to the norm, starting with a high-performance insulation system that addresses moisture concerns.
Icynene notes that the conditioned attic is recommended for hot, humid climates, not for cold climates.
| 
)
