Thermally Broken Cladding Attachment Systems

Rain screens provide virtually limitless design options for building façades while controlling moisture and reducing energy consumption

Knight Wall Systems manufactures versatile, ventilated rain screen façade attachment systems that accommodate a wide array of cladding options. Knight offers several attachment solutions and multiple rails for different insulation assemblies: the award-winning CI-System and HCI-System, which pair a drop-in facade attachment with rigid exterior foam insulation, enabling ASHRAE 90.1-compliant continuous insulation; the ultra-sustainable MFI-System and ultra-simple ThermaZee, which both utilize mineral fiber insulation. Knight prides itself on having inventory of all standard rain screen components in stock at all times, ensuring short lead times.

Industry Insights

The Definition: (per IECC 2021 and ASHRAE Standard 90.1-2019)

Continuous Insulation (ci): Insulation that is continuous across all structural members without thermal bridges other than fasteners and service openings. 

The Model Code Requirement: (per IECC 2021 Tables C402.1.3 & C402.1.4)

The minimum prescriptive R-Value Method (Table C402.1.3) requirements of the energy code for Climate Zones 5 & 6 requires Continuous Insulation (ci) for almost all above grade opaque wall types.  Assembly U-Factors must be calculated using a corrected R-Value for steel stud wall assemblies, effectively requiring continuous insulation in the assembly to meet the required assembly U-Factor.

The Massachusetts Stretch Energy Code Requirement: (per Section C402.7 Derating and Thermal Bridges)

In addition to pre-calculated assembly U-Factors, C-Factors, or F-Factors outlined in ASHRAE 90.1 Appendix A, vertical envelope performance shall also take into account the effect of thermal bridges.  Installed vertical wall continuous insulation shall be derated using either prescriptive, reference or modelled derating.  For modelled derating for Knight Wall attachment systems please contact Christopher Armstrong at carmstrong@pacerepresentatives.com.

The Challenge:

The thermal performance requirements of our building enclosures has increased significantly in the last 20 years. Increased performance requirements have outpaced readily available and understood solutions.  As a result, the actual thermal resistance of many opaque wall systems currently used does not achieve its intended thermal performance and sometimes does not even meet the minimum requirements of the energy code.   Many commonly used opaque wall systems achieve only 40-80% of their nominally rated thermal performance.

The Solution:

Engineered, thermally broken cladding attachment systems can support meeting the definition of Continuous Insulation and can provide up to 98% thermal effectiveness for continuous insulation solutions.  Make sure to work with a cladding attachment manufacturer that has comprehensive system thermal modeling to minimize derating under the Massachusetts Stretch Energy Code.

Click here for NFPA 285 & IECC compliant wall assembly Basis of Designs (BODs) for Climate Zones 5

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