Southern Pine lumber 2" and less in
thickness must be dried to a maximum moisture content of 19%
before it can be grade marked for structural use, so no further
seasoning is required prior to installation. For best performance,
however, all wood products should be protected from the elements
at the job site and properly acclimated if necessary.
In-Service Moisture Content
Wood-frame buildings perform best when the framing lumber at
enclosure is as close as possible to the moisture content it
will finally reach in service. The final in-service moisture
content of lumber in the building varies with the geographic
region and with location in the structure. Floor joists over
a crawl space may reach seasonal moisture contents in excess
of 14%. Roof trusses and rafters, on the other hand, may dry
below 6%.
Storage and Protection of Materials
Wood is a hygroscopic material that absorbs and releases moisture,
equalizing itself with surrounding conditions. Wood products
should be protected from the weather at the building site. They
should be unloaded and stored in a dry place, not in wet or
muddy areas. They should be elevated on stringers, not in direct
contact with the ground. Wood products stored in an open area
should be covered with a material that will give protection
from the elements, but be porous enough to allow moisture to
escape. Polyethylene or similar nonporous covers may trap moisture.
Wood products should be protected at the building site.
Acclimation of Finish Materials
Interior finish lumber, such as flooring and paneling, must
be protected from moisture and properly acclimated indoors prior
to installation. Exterior finish lumber, such as siding and
porch flooring, should also be protected from moisture and allowed
to properly acclimate outdoors prior to installation.
