Home Safety Foundation Study

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The Home Safety Foundation in cooperation with the Virginia Department of Forestry performed a two-year study of Wildland Urban Interface (WUI) initiated structure fires.  The study was funded by the National Institute of Standards and Technology (NIST), Fire Research Division.

Although there were several pathways for fire spread from the WUI to structures the predominant path was through a ground cover of leaves.  On-site documentation of the fires revealed  that a leaf layer only several inches deep on the ground was sufficient to ignite structures.

REPORT ABSTRACT

This report documents twenty-one structures that were ignited or significantly damaged by burning wildland vegetation in Virginia over a two-year period starting in 2015.  The structures included all of those that would have been lost except for the intervention of local fire departments or the Virginia Department of Forestry to suppress the fires.  The objective of the study was to supply data to NIST from WUI fire sites where structures were ignited including incident date, structure location, type of wildland vegetation that spread fire to the structure, and the first material ignited. Most of the incidents involved storage or utility buildings that were typically located away from residences where landscaped ground cover abutted a forested area on private property. Many of the structures ignited had wood or wood based exterior finish materials. Exterior finishes were burned and, in many cases burned through allowing fire to spread to the interior. In most cases, the fire was spread to the structure through leaves on the ground.  In those incidents, ground leaf and tree litter cover sufficient to spread fire and ignite the structures was estimated to be between 8 cm and 13 cm (3 in and 5 in) deep. Video from the 2016 Chalet Village WUI community fire (near Gatlinburg, Tennessee) showed that the same ignition mechanism played a role in the ignition of structures in that community.