Figure 1-2. Slope of Grain. (Slope of grain (A) is indicated by a ratio of
vertical to horizontal distance, such as 1 in 10. Slope of grain (B) is
evident from checks. The member at the left has a slope of grain much
steeper than allowed by structural grades. Slope of grain in the member at
the right is low enough to be accepted by some structural grades.)
not be used for structural purposes at all. There are, however, some factors that
may be kept in mind.
Moisture content is usually not an important condition factor where wood
is protected from rain and not exposed to unusually high humidities. Much old
lumber, which has been protected, is at a more or less uniformly low moisture
content. Further, large structural wood members have about the same design
values whether green or dry. Indirectly, a high moisture content is an unfavorable
factor in that it indicates that the member has been subjected to hazards of decay
or other deterioration.