A fire in an informal settlement is not just another small building fire. It can be the first domino in a fast-moving neighborhood event, and the little details like the wall material, roof material, door location, even a light breeze, can decide what happens next. I’m joined by Dr. Sam Stevens from Kindling to unpack a massive FSRI funded experimental program carried out in South Africa that burned twenty different informal and humanitarian shelter types to measure real heat flux, flame extension, and fire spread potential. 

We start repeating the uncomfortable gap: humanitarian guidance often relies on rules of thumb like a universal separation distance and vague advice to “use fire-resistant materials,” with little experimental evidence behind it. Sam explains how Kindling built a global database of shelter designs and materials, then narrowed it down to common typologies spanning sheet metal, mud, timber, bamboo mats, split bamboo, thatch, and tarpaulin tents. We dig into the field-scale test setup, why wood cribs were chosen, and how external instrumentation like thin skin calorimeters helps quantify the heat transfer that drives structure-to-structure ignition. 

Then we get into what the burns actually show. Non-combustible shelters often behave like classic compartment fires where openings dominate, but even modest wind can push flames meters outward. Add combustible walls or roofs and the hazard shifts dramatically: some materials produce short, intense exposure windows while others sustain burning long enough to threaten neighbors at greater distances. The fully thatched shelter stands out for extreme radiant heat and duration, and our discussion on tarpaulin tents reveals why common fire test methods can produce reassuring ratings that still miss real-world behavior. 

If you care about informal settlement fire safety, humanitarian shelter design, fire engineering guidance, or modeling large outdoor fires in dense communities, this conversation gives you a data-driven foundation and a clear sense of what questions still need answering. 

Learn more about the project and watch their educational videos here: https://kindlingsafety.org/projects/large-scale-fire-experiments-for-humanitarian-shelters/

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The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.