Knight Wall Continuous Insulation Rainscreen

Knight Wall System's GI-Girt rainscreen supports a variety of cladding option and provides continuous insulation across the exterior of steel framed buildings. Photo: Knight Wall Systems.

Happy New Year! I am going to keep the following blog fairly simple, mainly because Knight Wall Systems is interesting enough to deserve a closer inspection, so look for a more thorough follow-up product review in the Environmental Building News.

First some context...rainscreens used in non-residential buildings are typically made up of a metal framework that holds cladding away from a building's exterior weather barrier. The cladding keeps rain away from the building, and the space between the cladding and weather barrier allows any moisture that creeps in to escape. But in steel-framed buildings, the penetrations that connect the rainscreen to the building's steel frame provide a thermal bridge that transfers heat through the insulation, significantly reducing the R-value of the wall assembly. The problem is serious enough that in most climate zones ASHRAE 90.1-2007 now requires a continuous insulation barrier in steel buildings to provide that thermal break. Knight Wall Systems introduced its standard rainscreen system in June of 2010. This  "drop-in" system incorporates all the framing components and cladding, which simplifies specifying and installing the product, according to the company. The brackets that hold the frame are available in two-, four-, and six-inch sizes to accommodate different thicknesses of exterior insulation, and if the wall is out of plumb--as in retrofit applications--it can be easily adjusted (without shims) using its Stoffix "self-leveling" mounting system. The Stoffix system has minimal thermal bridging where the bracket attaches to the wall but it is not a continuous insulation barrier. But Knight Wall's CI-Girt (CI, continuous insulation) rainscreen system is mounted on top of the rigid foam board insulation (again, two-, four, and six-inch attachment options are available). The Gi-Girt is attached by screwing it in through the insulation. There are no brackets, and virtually no thermal bridging. The CI-Girt system does not have the leveling feature of the Stoffix system, but it does have superior R-values. Note: mineral wool can be specified with the standard Knight Wall Stoffix system but is not dense enough to support the CI-Girt system.

The company claims that by eliminating the thermal bridging, the CI-Girt system can provide an effective R-value of 16.5 on an R-15-insulated exterior wall; whereas a standard wall assembly using the same insulation would only have an effective R-value of 8.5 because of thermal bridging through the penetrations. According to Harley Simonson, one of the founders of Knight Wall Systems, "The CI is the most energy-efficient system on the market today."

The company is currently creating an eight-inch support frame for one customer to accommodate even more insulation and Simonson said, "We are in the process of designing an R-60 wall, which is unheard of in the marketplace."

Cladding options for the Knight Wall System include Stonel thin brick panels, StoneSheets (thin sheets of stone fused to a honeycomb aluminum frame), stucco, tile, metal, and cement and composite panels. The company also offers Boston Valley Terra Cotta. Simonson said different claddings can be installed on the same mounting system so a building can have the look of stucco, metal, and stone on the same frame.

The Knight Wall CI-Girt looks like a versatile rainscreen system. I'll track down additional performance data, talk with those using the system, and provide more details for next month's EBN. Hope you all have a peaceful, prosperous, and safe New Year!

Knight Wall Systems

509-262-0104

http://www.knightwallsystems.com

info@knightwallsystems.com

See more on this product in the GreenSpec Guide

Brent Ehrlich is the products editor at BuildingGreen