11. Structural failure in a roof may be due to
A. the presence of a vapor barrier between the attic floor and the ceiling below.
B. too little span between supporting members.
C. cuts made in rafters or trusses for addition of components such as stairways and fans.
*D. use of dried wood for structural members.
KD or Kiln Dried wood is premium material, unlikely to be the cause.
You are the inspector, the builders fear you because you may find their shortcuts.
To determine the correct answer, we need to understand what structural failure in a roof entails. Structural failure refers to the collapse or failure of the structural elements that support the roof, such as beams, trusses, or rafters.
Option A, the presence of a vapor barrier between the attic floor and the ceiling below, does not directly contribute to structural failure. A vapor barrier is designed to prevent moisture from passing through and may be important for insulation purposes, but it typically does not impact the structural integrity of the roof.
Option B suggests that too little span between supporting members could be a cause of roof structural failure. This implies that there is not enough distance or support between the structural elements, which could lead to excessive loads on the individual members and potential failure. While this can contribute to structural failure, it is not the best answer as there can be other factors involved.
Option C suggests that cuts made in rafters or trusses for the addition of components such as stairways and fans could cause structural failure. This is a valid consideration because any modification to the original structural elements, especially if not properly done, can weaken the roof's overall strength and stability. This option could be a contributing factor to structural failure.
Option D states that the use of dried wood for structural members can contribute to structural failure. This is the correct answer because dried wood is more prone to shrinkage and strength loss compared to properly treated or engineered lumber. Dry wood can become more brittle over time, potentially affecting its load-bearing capacity and leading to structural failure.
In conclusion, the correct answer to the question is D. The use of dried wood for structural members can contribute to roof structural failure.