All cutting and boring of holes should be done prior to preservative treatment. Cutting into the wood in any way after
treatment will frequently expose the untreated interior of the
timber and permit ready access to decay fungi or insects.
In some cases, wood structures can be designed so that
all cutting and framing is done before treatment. Railroad
companies have followed this practice and have found it
not only practical but economical. Many wood- preserving
plants are equipped to carry on such operations as the adzing and boring of crossties; gaining, roofing, and boring of
poles; and framing of material for bridges and specialized
structures, such as water tanks and barges.
Treatment of the wood with preservative oils results in little
or no dimensional change. With waterborne preservatives,
however, some change in the size and shape of the wood
may occur even though the wood is re dried to the moisture
content it had before treatment. If precision fitting is necessary, the wood is cut and framed before treatment to its
approximate final dimensions to allow for slight surfacing,
trimming, and reaming of bolt holes. Grooves and bolt holes
for timber connectors are cut before treatment and can be
reamed out if necessary after treatment.