Why Sounding the Floor Is Unreliable?

This article published in Fire Engineering talks about, 'The methods and materials used in the construction industry are continually evolving. Over the years, we’ve seen some distinct and significant changes in residential construction. One of the most notable examples was the change from balloon-frame construction to platform construction. With regard to fire spread, balloon-frame construction provided vertical void spaces that extended from the basement to the attic. These vertical voids enable a fire in the basement to spread rapidly to the attic through the walls of the structure. In fact, from a size-up perspective, you may see smoke or fire from the attic, which might lead you to the mistaken conclusion that the origin of the fire was in the attic. If you knew that this was a neighborhood with balloon-frame construction, you would know to check the basement before heading up. This construction method was one of the reasons behind what became known as the lowest-level check during size-up and initial fireground operations.'