most large timbers will improve the preservative treatment. In addition
many timbers will contain a pith center which results in deep radial season-
ing checks from the surface to the center. These checks often penetrate
past the treated zone.
220.127.116.11 Inspection Procedures.
Visual. The visual inspection of heavy timbers is similar to that for other
wood products. External evidence of decay includes features such as
fruiting bodies, abnormal surface shrinkage, such as localized depressions
or sunken faces on wood surfaces, loose joints, abnormal deflections,
crushing, cracking, etc., and insect activity. Remember, carpenter ants and
termites prefer damp wood.
Other visual evidence such as water marks from periodic wetting, rust
stains, especially if from wood-penetrating fasteners or hardward, and plant
growth such as moss or other vegetation, especially in cracks or crevices,
indicates that existing conditions are, or have been, conducive to decay.
Detecting Decay. Decay in heavy timbers is detected in much the same way
as previously described for wood poles. The "pick test" or probing can be
used to detect surface decay. Sounding by an experienced inspector may
provide some estimate of the potential for internal decay. Boring or coring
is used to estimate the extent of internal decay.
18.104.22.168 Remedial Treatments. Remedial treatments may be
either external or internal. External treatments include the elimination of
sources of moisture wetting the wood, and flooding the surface of critical
areas with an acceptable preservative. Pentachlorophenol has traditionally
been used for treating wood surfaces. New preservative emulsions have
some use because they can concentrate larger quantities of toxic preserv-
atives within a localized area.
For interior treatment of timbers, pressure injection of one of the water
borne preservative pastes, or borate or flouride rods in holes bored in the
timbers is effective. Application of liquid preservatives without pressure
can also be effective, but penetration is primarily along the grain of the
wood. The fumigants, vapam and chloropicrin, have been shown to be
effective in controlling decay in horizontal members. Boron and Fluoride
rods have also been shown to effectively control decay in large dimension
products such as poles and timbers.