Structure Separation Experiments Phase 1

These experiments were conducted during the first phase of project designed to assess structure-to-structure fire spread for structures in the Wildland-Urban Interface (WUI). The experiments focused on quantifying thermal exposures from auxiliary structures, e.g., sheds. The effects of shed sizes, construction materials, fuel loading, and separation distance on the ignition of primary structures (residential dwellings) with no wind have been studied and reported. Preliminary structure separation experiments using natural gas burners and an instrumented target structure were conducted to optimize instrumentation and experimental design for shed burn experiments. Full-scale fire experiments were conducted in which various sizes and types of sheds were used to generate typical radiative and convective heat exposures. In addition, indoor shed burn experiments with a target structure were conducted to assess target performance against exposures from varying sheds (construction, size, fuel loading) and separation distances. All experiments were performed without an artificially generated wind field. The exposures quantified in this study demonstrate that any auxiliary structures made from combustible materials can pose a significant fire hazard when placed next to the primary structure. For non-combustible source structures, the shed orientation with respect to the primary structure and the size of the door opening are critical factors. The findings from this study can provide technical input for national, state, and local building codes to alleviate fire spread from auxiliary structures within WUI communities.