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 of a musty. moldy smell, though indicative of conditions favorable to decay.
does not necessarily indicate the presence of decay.
The presence of fruiting bodies (Fig. 1-6) or "mushrooms;" indicates that
decay is present in members where the bodies occur. Fruiting bodies may appear
at any stage of deterioration.
When decay has reached an advanced stage, it is usually quite easy to decide
if the deterioration in a member is due to decay. especially if fungal growths
(fruiting bodies) are present. There may be localized depression or sunken faces
(Fig. 2-2) over decay pockets which extend close to the surface of the member.
Many times advanced stages of attack are accompanied by shrinking of the wood
and appearance of cracking in cubical patterns. Evidence of retained moisture
over a period of time, especially at the junction of timbers. often indicates attack.
A number of conditions provide visual evidence of possible decay. Area
exhibiting these conditions should be inspected carefully. Evidence of water.
such as watermarks, indicate areas which may be or may have been at a high
moisture content and thus should be investigated. Rust stains on wood surfaces
show possible excessive wetting, particularly if the source of the iron is a wood-
penetrating fastener. Appreciable growth of moss or other vegetation on wood
surfaces or in checks or cracks is evidence of potentially hazardous wetting.
Special attention should be paid to wood adjacent to water-trapping areas such
as within joints where end-grain surfaces occur and at interfaces between
members.
Damage by wood-boring insects is described in 1.2.3a.
2.2.1-C INSECT.
2.2.2 INTERIOR INVESTIGATION.
2.2.2-A SOUNDING. Sounding is accomplished by rapping on the out-
side surface of a member with a hammer. If the hammer does not rebound or
produces a dull or hollow sound, deterioration probably exists. This method
requires considerable experience and can be considered truly diagnostic only
where decay is relatively severe and, in large members. extends to areas near
the surface. Wood members suspected of containing internal decay. as a result
of sounding. must usually be bored to verify the diagnosis.
Sounding can also be used to detect loose connectors. Rapping on a bolt
head will produce a clear, solid ring if the connector is tight. A loose connector
will produce a hollow sound with more vibration than a tight one. Experience
is also necessary to effectively evaluate these sounds.
2.2.2-B BORING. Boring is the most dependable and widely used techni-
que for detecting internal decay. This method has the advantage of permitting
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