AIR DRYING LUMBER
|First I will make a mention here that this is
a very simple, easy way and only applies to drying lumber for
the 1 man sawmill or homeowner sawmill, it will not include
all the formula’s etc, just the basics for you.The water
or moisture content (MC) in lumber or logs is significant and
can be 100% in the lumber or log. So how dry should it be to
use. An average percentage to use is around 20% or less if
the lumber is too be used outside (optimum is 15%) and if the
lumber is going to used inside, then around 9% is normal. A
moisture meter probe is a really good item to have but these
can be expensive.
|It is advisable to mill logs as soon as
possible after the tree has been felled. If this is not possible
and the log is going to sit for a while then you should coat the
end of the log (both ends) with a sealer to slow the
drying process down. You can use a regular grey aluminized patching roof sealer
which is available at just about any hardware or home
building supply store. This is soft, thick, and comes in 1
gallon cans and you can use a brush to apply. I have found
there is not too much difference between the proper lumber
/ log sealers (expensive) and the roof sealer, which is very
If the logs are going to sit for quite a while before you mill them into lumber
then it is advisable to take a strip of bark off the full length of the log (about
2” wide) at 3 equal spaces around the log. This allows the moisture to
escape from the log more evenly and not just out of the ends of the log.
The sealer acts like a barrier so the moisture can escape through the strips
taken off the log.
Not coating the ends and just leaving the log then the moisture will travel along
the grain of the log and will escape mostly out of the ends of the log. This
will produce far more checks, splits in the log and depending on the species
of tree these splits can be quite long into the log.
Air Drying Lumber
|Depending on the thickness of the lumber and
where you live, weather and time of the year, it will take
anywhere from 6 weeks to 4 months. Most lumber is in the 1” to
2” thickness and the time above applies to thicknesses.
Drying cants, timbers, posts will take considerably longer.You
must stack the lumber correctly, this is imperative if you
want good grade lumber to use. If you do not take the time
to stack the lumber correctly, then you are going to loose
a fair amount to warping, checks, splits etc., you must also
coat both ends of the boards with a sealer.
You must pick a place to stack the lumber
that is as flat as possible and you must cover the ground
with plastic, tarp or plywood etc. You do not need to do
this if there is enough air circulation under the stack.
The start of the lumber stack should be at least 1ft of the
ground, 2ft is better. You can make the base out of old railroad
ties,, concrete blocks or slab of 2 sides of a tree on Procut,
use anything at all that is square and you can get up to
1ft to 2ft high. This base MUST be level and even with each
other, the flatter you get it, the straighter the lumber.
If the base is not even the lumber will dry with the contour
of the base, so it must be as flat and straight as you can
Lay down 3 separate pieces the length of the longest lumber you are going to
cut. These main supports should be separated about 3 feet apart. Across the main
supports lay more supports at 2 foot spacing and this is what your lumber is
going to be placed on. Once this is done just make sure the cross supports are
all even with each other.
Now you are ready to stack your lumber.
You should have lots of sticker sticks handy.
These are just 1” x 2” and they should be dry
lumber sticks. Lay a first row of stickers on top of the
cross supports, lay a course of lumber on these
sticks. The lumber should be separated by at least 1” gap
between each piece, then lay stickers across the top of
this course of lumber. Make sure each sticker is on top
of the previous stickers so there is always support throughout
the pile. Each course of lumber should have the ends supported
at all times with sticker sticks. Using lumber that is
all the same length is nearly a necessity as each sticker
should be on top of the one below. If you are going to
mix in shorter pieces then make sure they are butt ended
and the ends are still supported with stickers. Make sure
there is a 1” gap between all the sides of the lumber
on every course you lay and again, make sure there are
stickers at the very ends of all lumber and each sticker
is on top of the one below. See drawing.
You can go up as high as is comfortable to
load the lumber. I have found that 5ft is about as high as
you should go. 4ft is better because if you try to go too
high it makes it really hard to lay the lumber without disturbing
the stickers that you have placed. If you have help
then it does make it easier to go higher on the stack. The
stack can also be as wide as the base supports. Once you
get to the top of the stack. Lay thicker stickers across
the last lumber course and if possible wider than the stack.
The very last thing then is to cover the stack of lumber
with plywood, tin roofing etc and weight this cover down
with concrete blocks, old steel, anything that has weight
Try to get this weight to sit on top of the last stickers
underneath. This will prevent the top layers of lumber
from warping. You should also try to get this top
cover so it is longer than the ends of the lumber. You
can lay plywood or a small tarp over then ends of the lumber,
just make sure there is lots of room here. Using plywood
is good because you can just lean against the top of the
stack. You are doing this to prevent the rain and sun getting
in direct contact with the ends of the lumber. There is
nothing worse than direct sun on the ends of the lumber
as this draws out the moisture faster in the ends of the
lumber and they dry out faster creating cracks warps etc.,
in the ends of the boards.
The next is a tedious job but it will slow down the drying
process in the ends of the lumber, you should coat
the ends of the lumber with the sealer or roof coating. This
does take a little time to do and is the correct way, but
I have found it is o.k. to just cut the lumber longer than
needed, then trim off the ends to the correct length you
need after drying.
So you may wonder how much is in a stack of lumber so you
know how many bases to make.
4ft high x 6ft wide - 2” x 4” lumber
18 high ( 1 board over 4ft ) x 14 wide - 252 pieces
4ft high x 6ft wide - 2” x 6” lumber
18 high ( 1 board over 4ft ) x 10 wide - 180 pieces.
So now you have your lumber stacked, there is a gap
between the sides of all the lumber, there is a gap between
the each course of lumber and this allows a free flow
of air throughout the pile.So this may seem a long winded
explanation on just how to dry lumber, but it is better to
do it properly and have a good grade of lumber to use, all
nice and straight, no warps or splits etc.
Allan at Procut
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