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Wood with readily apparent decay should not be used as a primary struc-
tural member or where strength requirements are high. At the same time, if only
moderate strength is required and if decay is clearly localized, the piece of lumber
may have some value, but must be evaluated by a professional.
Deterioration from heat or chemical attack is hard to appraise. inquiry into
the service history of the structure may uncover some helpful information. If
there is evidence of any considerable effect from this cause, it will be safer not
to use the lumber. For example, timber that has been in close proximity to steam-
heating pipes may become brown and crumbly, an indication of strength loss.
1.2.2 CONDITIONS OF USE. The way wood is used in a building has
a major effect on the maintenance required and the potential for problems of
deterioration. Wood is affected by exposure to excessive moisture, high
temperatures. or excessive structural loads. The age of the building or the time
period over which the wood has been exposed to these conditions is also impor-
tant. The exposure of structural wood to the elements as a result of design features
or inadequate maintenance can also be a contributing factor to deterioration.
LOADING. Normal operations carried on in a building can contribute to
deteriorating of wood, especially if the function was not considered in the original
design. Any operation that involves a lot of water (Fig. 1-3) or steam (Fig. 1-4)
increases the potential for the wood to be at a high moisture content and for
consequent decay or possibly insect problems. Some examples are shower rooms,
swimming pools. and laundries. The high humidity resulting from these opera-
tions may cause condensation on cold surfaces with resultant wetting of the wood.
Problems may also develop where water contacts wood or where steam from
driers or steam lines is close to wood members. Various manufacturing or pro-
cessing operations may also introduce excessive moisture to the inside of the
building. Although adequate ventilation may have been included in the design,
these high moisture situations should alert the inspector to a greater potential
for decay than in a building that is consistently dry.
Most trusses and arches are designed to support only normal roof loads.
Additional loads may overstress structural members. particularly if these are
applied over a long period of time. Examples of such loads are mechanical equip-
ment such as air conditioners or elevator motors, antennas or other communica-
tion equipment mounted on the roof, hoists hanging from the lower chords of
trusses. or other heavy items stored by hanging them from trusses or arches.
Some of these loads can be applied temporarily without ill effects, but can cause
serious problems over a long time period. A description of any unusual loading
and the time over which it has occurred should be noted in the inspection report.

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