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 direct examination of an actual specimen from the questioned area. Use of this
method should be limited to areas with conditions suitable for decay. In taking
boring samples, it is important to use sharp tools. Dull tools tend to crush or
break wood fibers, which changes the appearance of samples. Inspectors should
carry extra bits in their supply of equipment because cutting edges are easily
damaged beyond practical field maintenance by striking hidden fasteners. Bored
holes may become avenues for decay unless properly treated. Following shav-
ings extraction. a wood preservative should be squirted or mopped into the hole
and the hole then plugged with a snug-fitting preservative-treated wood dowel.
2.2.2-C PROBING. Decay soon causes wood to become softer and to lose
its strength. If decay is suspected, the area should be probed with a pointed tool
and its resistance compared with that of obviously sound wood. Probing may
reveal the presence of decay by excessive softness or lack of resistance to probe
penetration. Early decay may also be detected by jabbing the probe into wood
and prying down. Sound wood usually breaks out in long splinters, and decayed
wood is brittle and breaks out in short pieces with abrupt across-grain breaks
(Fig. 2-3). Probe in areas where water is likely to have been absorbed or trap-
ped by wood such as end-grain or side-grain faces adjacent to joints, deep checks,
and adjacent to penetrating fasteners. In large members, particularly if preser-
vative treated, neither probing nor sounding are effective in detecting decay at
deep locations. For most critical appraisal of members likely to to develop hidden
decay. boring is necessary.
2.2.2-D MOISTURE CONTENT. Where excessive moisture in wood is
suspected. a moisture meter is used to determine moisture content. Pins of the
moisture meter must be driven to near the center of the wood member for accurate
determination. Specific instructions are included with individual meters.
2-7
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