Old Fracture or New Fracture?

Posted by in Simple Forensic Methods, Wood | May 04, 2020

Roof framing that has been exposed to a substantial weight of ice and snow exhibits fractures (see the featured photograph).  Were the fractures caused by the recent accumulation of ice and snow?  How can the history (age) of a wood member fracture be determined?

When previously encased wood material is exposed is appears clean and exhibits a natural wood color.  After the newly exposed surface is subjected to air, direct sunshine, and/or moisture, the color of the surface slowly changes.  The change in color is more visible as time progresses.  When the exposed surface becomes wet or damp, the surface can become stained and/or decayed.  When the exposed surface is subjected to air movement it often accumulates dust and/or debris.

The degree of the color change, the staining, the decay, and/or the accumulations of dust or debris can give insight into how long the wood surface has been exposed.  These phenomena are helpful in determining whether a fracture occurred relatively recently or it has been present for years. 

For example, the fracture seen in the ridge board on the featured photograph is due to the excessive dropping of the ridge board, but did it occur over the past six months?  A closer examination of the cracking discloses the darkening (discoloration of the natural color) of the exposed surface and a heavy accumulation of dust (Figures 1 and 2).  Conclusion: this particular fracture did not occur during the past six months as proposed. 

Figure 1 Fracture in ridge board.
Figure 2 Fracture in ridge board exhibits discoloration (loss of natural color) and heavy dirt accumulation.

Additional information corroborates this conclusion: the newer vertical member fastened to the nearby rafter indicates that it was noticed by someone who added a permanent shore long before the snow storm (see the feature photograph).