I will be airdrying my lumber any advice out there

[jldoss1]

Im looking into different mills and when i get started i'll prob. airdry. I was wondering if any of yall have any tips on how you do it, lenght of time, how you stack and strip. Oh and i will be stacking outside is this a suitable way to go about it. I know thats how the oldtimers use to do it.There are'nt any codes to worry about here in rural arkansas, but i still want a good quality product in the end.

[Dan_Shade]

I have this on my website, and provide to folks when I do a job for them, I've put it on the forum before (I actually copied it from another post:   https://forestryforum.com/board/index.php/topic,37703.0.html )

Typically, for air drying lumber, it takes one year per inch of thickness for the wood to dry to a usable state. In the Mid-Atlantic region, wood will air dry to approximately 12-14% if properly stacked and sticked.  Lumber over 2" thick is difficult to dry, and may develop specific drying defects.

It is best to have the lumber stack as level and flat as possible.  Variations in the stack will translate to the lumber in the pile, if the stack is not flat, the wood in the pile will dry warped.  Stickers should be aligned on top of each other in the stack and be placed 18-24 inches apart.  The stack should be well supported with blocks to combat the beams sagging from the weight of the lumber.  The bottom of the lumber stack should also be elevated 12-16" off of the ground, to keep weeds and animal impacts to the pile at a minimum.  The platform should be constructed as long as the longest lumber is, and stack width is best when 4 to 6 feet wide. 

The pile should be weighted down and the top covered.  Covering the sides of the stack with a tarp will result in moldy lumber.  Air must be able to move through the stack.  Lumber should be stacked and sticked within 24 hours of being sawn to avoid mold problems.  Mold develops quickly during Spring and Summer on pine wood.  A light mixture of bleach sprayed on the wood stack helps inhibit mold growth, but mold may still develop if it is warm out.

Wood stacks should be left in an open, but shaded area where airflow is not inhibited.  Direct Sunlight may cause drying defects. 

Lumber losses due to material degradation (warp, check, stain, etc.) can be expected while drying.

Additional information can be obtained from the USDA Forest Products Laboratory, General Technical Report FPL-GTR-117


Also, check out this link:  https://forestryforum.com/board/index.php/topic,48182.0.html

[eastberkshirecustoms]

I think there's another new thread on here discussing air drying, you might also want to check that out for the answers you seek.

[WDH]

Depending on species, stack width is key.  Oak, walnut and cherry are forgiving.  Maple and yellow poplar are not.  If your stack is too wide, there is not enough air flow for some species like maple, yellow poplar, and pecan.  Your will lumber will get gray stain (an enzymatic reaction that stains the wood in ugly gray splotches) or like especially with yellow poplar, the outside of the lumber can turn almost black with mold and mildew.  Pine can also stain, mold, and mildew if not enough air is moving thru the stack.  Four foot wide is the maximum for these stain prone species.  If in doubt, keep it to four feet.  Wider is OK with oak since it needs to dry slow anyway, is not prone to stain, mold, or mildew.  However, like was mentioned before, do not go above six feet in width.

Unrestricted air flow is key.  Do not stack next to a wall.  All that water leaving has to have somewhere to go and get away or it will be your enemy.  The stack has to be under a shelter or have some type of roof covering over it, even if it is just tin.  Leave a space between the top layer and the roof.  Remember, the evaporated water has to have somewhere to go. 

[tcsmpsi]

Good for you on the codes.   Lets us that do yet have that freedom, work to keep and nurture it.

My primary drying is done in the wood/mill shed.  (I reckon there ain't no 'too big' for one of those)  It is well open, but mold/mildew is pervasive in these parts.  I use fans to control the airflow (more,less, up, down, etc.) depending on circumstance/wood.  Sometimes, there may be multiple species in a stack.   My primary stack is 5' wide, sits on posts and beams (permanent) about 16" off the ground.   About 6' above the beams is about all I can reasonably stack, and still weight as well.  That is used for my bulk of SYP.   Always some other specialty stacks going on, and some SYP overflow, from time to time.  Control of the air with the SYP, it can be dried and stacked quicker, without causing it any 'grief'.    ;D

The big, tall stack on the right is my primary drying rack.



 

[WDH]

I use a box fan blowing alongside the stack (not directly into it) for a couple of weeks for maple and pecan to make sure that the air has a little movement to prevent gray stain.  The gray stain happens very early on in the drying process if the humidity gets too high and stays too high for too long. 

No fan for oak as it cannot be dried too fast or it will check and honeycomb on you.  Walnut and cherry, you can just stack it in the proper place and just forget about it.

[slider]

what about syp ? how long would you keep a fan going it in the summer time.i don't get much mold problems in the winter.i use bleach in the summer but it is a pain to apply.probably need to invest in a moisture meter  .i am speaking of wood under a shed.   thanks  al

[GAB]

To: jldoss1
When I stack lumber I place at least 2 layers of plastic on the ground to prevent the moisture from affecting the lumber in the lower portion of the stack.  I use pieces of ag bags that my brother uses to pack feed in in the summer.
Also, avoid using freshly sawed material for stickers as wet stickers will generally sticker stain the lumber.  The depth of the sticker stain will vary depending on species, moisture content of the stickers, environmental conditions, etc.
The covering over the pile should overhang by quite a bit to protect the lumber from wind driver rain and/or snow.
GAB

[tcsmpsi]

Slider, I keep the fans on the syp until it is dry, in the summer down here.   Generally speaking, 3 to 4 weeks. 

[cutterboy]

Perhaps drying lumber in the South is more difficult than up here in the North because of the heat and humidity. I think Dan Shade and WDH have given good advice. I have only had a mold problem once in ten years of drying lumber. That was in a stack of white pine sawed in the summer and only a dozen boards were affected. However, there are always a few boards in every stack that will bow, twist, or cup.

tcsmpsi, you have a great place for drying lumber. Nice and open but under cover.

jldoss1, Don't be nervous or worried about air drying lumber. Use your common sense and the basic advice you've got here and you will do fine.

[rbarshaw]

I also use a fan blowing directly into the stack for SYP.

[WDH]

In the big pine mills, green SYP is dried to 19% moisture in 24 hours.  Yes, that is 24 hours  .  So a fan on the stack will only speed drying.  You have to be much more careful with hardwood and especially oak and especially white oak.  You will ruin it if you try to dry too fast.

There are tables for the maximum amount of moisture loss/day that a species can tolerate.

[tcsmpsi]

Down here in the thickets, mold/mildew starts to grow on spit before it hits the ground.   :D 

WDH is right about the oaks.  I won't even think of using them for anything until they've set 3-4 yrs.  Sometimes I will put them on the lower parts of other stacks, and fan the upper levels. 

The next add-ons to the 'shed' are already planned out, cutterboy.   ;D   

Still, it amazes me as to how much mold/mildew can grow down here overnight on freshly milled syp.  Maybe I can find a market and harvest it.   :D

[Meadows Miller]

Yeah we are down to 10 to 12hrs for a 43000bft chamber of 2x material in the Hi temp kilns running at upto 250deg  Dad built his own 6800bft Direct gas fired kiln in about 86 using bricks a solid back wall with rows of bricks on edge with the holes providing the cross flow in the heat tunnels down each side as the outside wall was timber frame with shiplap boards on the outside and cement sheet lining the tunnel and a 7' single fan which has to be even as you will get uneven drying otherwise it use to do a charge of 2x in 18 to 20 hrs running at 210deg it was a dang good kiln and went for years not bad on a $12000 build cost I intend on building our own one day as it was a dang good kiln    ;) ;D 8)

With the air drying try not to make your packs any more wider than 4' hights not an issue what I have done is put two rows about 1' apart in the center then what happens there is it creates a flue like draw convection current apart from the fact the air is moving downwards as wet air is heavier than dry  ;) Fans help but you need to get even flow as Airspeed is king with drying pine the more dry air you have moving across the charge the more water your pulling out thats why I use full inch sticks when im doing stuff like that its only when im trying to cram as much as I can into a Kiln where i become verry tight with my stick thickness case every extra bft per charge you can fit in sves drying costs and increases production per charge  ;)

I hope this helps

Regards Chris