Design practices in framed wall construction rely largely on exterior insulation to comply with current energy codes and continuous insulation requirements. New challenges accompany this paradigm shift, including implications for NFPA285 compliant wall assemblies, tolerance to wetting events, and the continuity of thermal layers. This presentation examines the performance of exterior insulation in response to the demanding conditions found in
modern rainscreens and masonry veneer cavities. Particular emphasis is placed on NFPA285 compliance, thermal bridging, moisture transport, and the effects of wind-washing in ventilated rainscreens. These advanced perspectives will empower professionals to design, specify, install, & achieve the benefits of exterior insulation while avoiding its unintended consequences.

Learning Objectives:

1. Understand current building code requirements and testing methodologies for fire propagation and smoke development. Given assembly testing following the Grenfell tragedy, attendees will better understand fire propagation in relation to actual material properties and performance.
2.  Review material properties governing moisture and air performance as they pertain to conditions encountered in rainscreens and masonry veneers so as to best understand the performance characteristics of insulation specification choices.
3.  Understand conditions that pose unique challenges, including multiple drain planes, drainage efficiencies, increased water absorption, and water vapor transmission. Recognize risks associated with exterior insulation when used in combination with cavity insulation, interior vapor retarders, and low-perm water-resistive barriers.
4.  Understand the effects of wind-washing and convective heat loss in modern rainscreen systems. Identify and prevent conditions that jeopardize the thermal insulation layer, which may in turn affect moisture transfer and overall wall performance.

Lance Williams

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