Procut Portable Sawmills in Prince George, BC

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.

Logs

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 cheap.
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.

Stacking Lumber

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 get it.
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.

Air Drying Lumber

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 to it.

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.

Regards
Allan at Procut

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PROCUT Portable Sawmills
2468 McBride Crescent
Prince George, B.C. Canada V2M 2A1
Phone: 1-250-562-6422 or Contact Us


   
 

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