"Dirty Cobwebs" or Soot Webs
When inspecting a home or business after the property has experienced a fire damage, owners sometimes mistake soot webs as being "dirty cobwebs". During a fire, smoke particles cling together like magnets forming a chain of soot. The chain will stick to areas that tend to be cooler such as along the outside edges and corners of the ceiling.
In this particular situation, a faulty dehumidifier in the basement of a ranch home caught fire. Smoke and soot effected not only the basement level but traveled thru the floor joists, walls and the HVAC system filling the home with a layer of soot.
As you can see in the before picture, smoke particles stuck together forming soot webs in the floor joists. SERVPRO of Holland/W. Ottawa Co. uses specialized equipment and techniques to remove smoke and soot from ceilings, walls and other surfaces.