When people think of the incredible destruction caused by the 1906 San Francisco earthquake, they typically think of buildings crumbling to the ground from the tremors and aftershocks. In reality, the greater damage was done by the hundreds of fires that broke out across the entire Bay Area.
With many water lines broken, there was little the San Francisco Fire Department could do to contain the destructive blazes. Fortunately, many of the city blocks contained rows of houses built of naturally fire resistant redwood lumber.
Most trees have resins, a highly flammable substance that contributes to the rapid spread of wildfires in both forest and urban settings. Instead of resins, redwood has tannins, a naturally occurring substance that is significantly less flammable and makes redwood naturally fire resistant.
In fact, when the dust had settled and the final embers went out after that horrific natural disaster, P.H. Shaughnessy, Chief Engineer of the San Francisco Fire Department wrote in his official report, “…if the exterior finish of these buildings had not been of redwood lumber, I am satisfied that the area of the burned district would have been greatly extended.”