Acclimatize
Siding
 |
One of the most
stable softwoods, Western Red Cedar is nevertheless
a natural material and it responds to the
environment. Cedar siding can swell or shrink
as it gains or loses moisture to reach equilibrium
with the moisture content of the surrounding
air. Ensuring that the moisture content of
cedar siding is at equilibrium before it is
installed will minimize movement later on.
Recommended moisture content for sidings used
in various regions of the country are given
in Table 1. |
On the job site, keep the wood dry. Stack siding
off the ground and under cover. If the wood is to
be stored over damp ground or new concrete, place
a moisture barrier under the siding. Siding should
be 4" to 6" above the ground with air
circulating freely around and throughout the stack.
Acclimatization time varies with the moisture content
of the siding. The following procedures are suggested
for different siding specifications.
Kiln Dried Clears
 These have been dried at the mill to 12-15%
moisture content. They are the most ready-to-use
of all siding products. If the siding has not been
wetted prior to arrival on the job site it may be
applied upon arrival except in the Southwest where
3 to 5 days of well ventilated storage is generally
required. If the siding has been wetted it must
be separated and allowed to dry thoroughly before
installing.
Dry Knotty Sidings
Knotty sidings are air or kiln dried to less
than 19% moisture content. Stack the siding on evenly
spaced, vertically aligned stickers (Figure 1) in
a dry storage area for 7-10 days. More time may
be required in damp or humid conditions.
 Green (Unseasoned) Sidings
Unseasoned or green sidings have not been
dried prior to delivery and require a longer time
to acclimatize than seasoned sidings. Separate
the siding with vertically aligned stickers (Figure
1) and store in a well ventilated dry location
for a minimum of 30 days or longer in damp or
humid conditions. If specifying unseasoned siding,
patterns such as channel, bevel and board-and-batten
are recommended since these allow for shrinkage.
Narrower widths are also recommended since these
move less overall than wider widths.
Table 1. Recommended Moisture
Content for Siding Installation
| Most Areas |
Dry, Southwest States |
Damp, Warm Southeastern Coastal
Areas |
| Average |
Individual Pieces |
Average |
Individual Pieces |
Average |
Individual Pieces |
| 12% |
9-14% |
9% |
7-12% |
12% |
9-14% |
1. To calculate average, test 10% or more of pieces.
2. Source: Wood Handbook 1987. |
