Tech Talk: Building Fire Safety in Wildland-Urban Interface Zones

The Wildland–Urban Interface (WUI) is a zone of transition between wilderness and land developed by human activity – an area where a built environment meets or intermingles with a natural environment. Human settlements in the WUI are at a greater risk of catastrophic wildfires.

The definition for WUI Zones speaks to the ever-present danger to structures, that have been built adjacent to wildland that’s covered with highly flammable under and overgrowth.  Sadly, over the last decade, there have been too many examples of structures, and even whole communities, consumed by wildland fires.  With past and recent wildland fires as actual evidence of the fire risk to structures becoming fire-involved, the Building Codes – ICC International Codes, California Building Code, Los Angeles Building Code, Washington State Building Code and others - have reacted by establishing in their building codes, fire resistive measures that are intended to reduce the fire risk to structures constructed in designated WUI Zones.  These required Building Code fire resistive measures depend on the severity within the WUI Zone – designated as either moderate, high or extreme hazard.

In general, these WUI Zone Building Code fire resistive measures, include constructing the structure to be protected from fire involvement in a wildland fire event, by using a combination of an underlying code-compliant non-combustible sheathing to the exterior surfaces of the structure before the installation of exterior wall, soffit and roof cladding materials and systems.  The wall, soffit, and roofing cladding materials may also be non-combustible, but may not be required to be used in moderate hazard WUI Zones.   The WUI Zone Building Codes site numerous fire test standards, such as ASTM E 119/UL 263, ASTM E 108/UL 790, and ASTM E 84/UL 723 as tests for building materials and systems that provide evidence for code compliance for use in WUI Zones.

Premier SIPS have been extensively tested under the aforementioned fire standards required to comply with the multiple WUI Zone building codes and thus has been granted recognition to all WUI Zone requirements by ICC Evaluation Services.  Premier SIPS’ ERS-4524 contains language that shows compliance with the California Building Codes, the Los Angeles Building Codes, and the broader national scope, International Wildland Urban Interface Code.  Both residential and commercial structures can be constructed with Premier SIPS, meeting WUI Zone requirements.

Learn more about SIPs and Fire Performance here.