Lab Experiments Simulate House-to-House Fire Spread

The experiments were conducted July 19 at the NIST Large Fire Facility. The tests, along with additional tests conducted on July 27 with more fire-resistant structures, are part of a program to develop computer models for predicting the spread of fire in residential communities.

As land prices continue to rise, homes are being built closer together, many without fire-resistant materials. Building officials need information about the rate of fire spread in communities under various house spacing, construction methods and materials, and weather conditions. Fire departments also have to understand the time required for fire spread from one house to another in order to provide adequate response.

Each experiment conducted at NIST involved two 16-foot structures clad in vinyl siding that simulated neighboring houses. The outside walls for each structure included windows. In the July 19 test, typical home furnishings were ignited in one “home” and the fire spread was recorded, along with heat release rates and other data. In less than five minutes, flames shattered the window of the home with the original fire, spread across the gap, and ignited the exterior of the second structure.

The July 27 experiment measured the effects of a fire-resistant barrier in the exterior wall. Flames from the first structure again reached the second in about four minutes, but this time, the gypsum barrier prevented the fire from significantly damaging the simulated home.

NIST plans to summarize its results once an analysis of the tests is complete. Officials considering house separation regulations and/or the inclusion of fire-resistant barriers on exterior walls should find such fire spread data useful.