Drying time for green wood?

[Joe Shinall]

Ok, so I have a lead on a guy that is selling green wood for .55 a board foot. He is a trucker and drives up to West Virginia and buys trees, brings them back and has a bandsaw mill and cuts to dimensions. So I'm picking up some cherry, maple, chestnut, and white oak from him next week. He is cutting into 1" and 2" thicknesses.

Question is, how long does it need to dry when stacked? I've heard a year for every inch. Is this true and does it dry faster with fans on each end constantly on?

[Scott T Smith]

Ok, so I have a lead on a guy that is selling green wood for .55 a board foot. He is a trucker and drives up to West Virginia and buys trees, brings them back and has a bandsaw mill and cuts to dimensions. So I'm picking up some cherry, maple, chestnut, and white oak from him next week. He is cutting into 1" and 2" thicknesses.

Question is, how long does it need to dry when stacked? I've heard a year for every inch. Is this true and does it dry faster with fans on each end constantly on?

Joe, do yourself a favor and pick up a copy of Dr. Gene Wengert's "Drying Hardwood Lumber". There is much more to drying than can be covered in a few paragraphs.

Drying rates vary depending upon species and thickness. The "1 year per inch" rule is not accurate.

You can easily damage the wood during the drying process, and too much airflow (above 350 fpm or so) will probably damage it, at least in the early drying stages (above 35% MC).

Your miller needs to either treat the ends of the logs with a high quality end sealer (such as Anchor Seal Classic) before transporting them, or plan on cutting off 5" or so of the ends of the logs after transport and before milling. The reason why is the airflow past the ends of the logs will be in excess of 5300 fpm during the trip from WVA to GA - well in excess of 350 fpm! The checking that starts during this time will continue on through your boards, much as a crack in glass will extend itself.

Also do a search on the archives here for drying related info.

[Joe Shinall]

Scott, he does user anchor seal on the ends before transport. It's good to hear you say that, because I didn't know that was needed until he said it and then that solidifies it. I'll pick up that book and see what I can find.

Can you recommend a good moisture meter by chance(reasonable cost but still good)?

[Howard Acheson]

Initial dry should be outdoors with the wood stacked and stickerred. The stack should start 8-12 inches off the ground with a plastic tarp under the stack. Position it so that air can blow through the stack without hinderence. Put a cover on top to keep rain off it. Get a moisture meter. When the moisture gets down to 18-20% EMC move the stack indoors but be sure that air can move through the stack.

The time is a variable that depends on the relative humidity, species of wood, thickness of wood and air movement. Wood dries faster in the summer typically. Total time could be 6-12 months per inch.

[Joe Shinall]

Howard, pardon my ignorance, haven't really dealt with a lot of green wood. But what do you mean by stickered?

[Joe Shinall]

I just downloaded and read about 2 chapters of the Drying Hardwood Lumber...Wow! I feel like I need to be a rocket scientist to read this!

Ok, so I have a shed that's a lumber storage. It's 16 x 20. It is not insulated so it is pretty much the same temp inside as it is outside. I also have windows that I leave open most of the time to allow airflow in. Is this a good place to stack it or do I really need to find a place outside to stack it initially?

Edit: Nevermind, just looked up stickering wood and got the explanation. Didn't know that was called stickering, but it's what I do with all my stacks. Learn a new word every day.

[Dave MacArthur]

Well THIS is going to be an adventure! ;) Lead the way, Joe, and ask all the questions. There surely is a TON of info and skill in drying wood and producing lumber--I've read enough threads on this to know that at least. I've been thinking about acquiring trunks from storm damaged trees around here for a while, so it will be a worthwhile thing for me to follow your adventure. Please do keep posting how it turns out, especially any mistakes and painful parts--remember, there are a lot of lumber-wannabees like myself counting on you to sacrifice yourself for the cause ;)

I do read all the threads I see on milling logs, drying boards, dealing with checking, dealing with insects, solar kilns, air drying, etc. It's interesting stuff, despite having never done it myself. If you do a search using Scott T. Smith as the author, Scott has written some quite extensive posts on all these topics, and I've found his answers to be informative and well considered.

Erm... I'll admit I have two mesquite logs about 5' long laying in my side yard, waiting for the day I'm ready to take on slicing them. By now, having sustained 2 summers in Phoenix on the 140F gravel, they're probably 1% MC, and also likely infested and sterilized about 40 times by now. I tell myself that in the worst case, they'll make excellent chips for my smoker and steak cooking.
Good luck!

[Dennis Ford]

This is a great thread. One thing to be aware of; drying wood in Phoenix and drying wood in Savannah have one thing in common (wood). Virtually everything else will be different. In East Texas, the humidity tends to be high and it is important to have plenty of airflow initially to prevent mold/mildew from staining the wood. Once the free water is almost gone, the drying rate should be slower to prevent cracking. In a dryer climate, mold will be less of a problem but drying too fast and cracks will be more of a problem.

[Howard Acheson]

>>>> Ok, so I have a shed that's a lumber storage. It's 16 x 20. It is not insulated so it is pretty much the same temp inside as it is outside. I also have windows that I leave open most of the time to allow airflow in. Is this a good place to stack it or do I really need to find a place outside to stack it initially?

For initial drying, outdoors is best. You need a good flow of air through the stack. It will give you the most consistent drying. Slow, consistent drying is necessary to prevent damage to the wood.

As I said above, temperature is not as important as RH. In fact, unless you know what you are doing high temperatures can cause problems in the wood. Personally, I never advise putting wet lumber in an uninsulated attic. It can cause checking, splitting and case hardening. Oak is particular susceptible to drying problems.

[Joe Shinall]

Ok Howard, I like the info you're giving me. So if I setup a stack like you said, about 8-10 inches off the ground and stickered, when I cover it, do I just cover the top or do I cover the whole pile?

I would assume to cover the whole pile all the way around but that makes it where air flow cannot get around. Can I set up a tent with both ends open that covers a few feet over the edges so the angle rain doesn't hit the boards? Would that be sufficient for outdoor drying?

[John TenEyck]

Your stickered stack should look something like this. DO NOT cover the sides or ends, just put a piece of corrugated or similar on top. Put stickers under that, as well, so that air can flow across the top layer. Make the stack somewhere where it isn't directly exposed to a lot of sun but has good airflow. The stack in the photo is under a few shade trees, under an open shed would be ideal. Air drying wood in Savannah sounds like an exercise in patience with your high humidity, but clearly it can be done 'cause some beautiful furniture has been made there over the past couple hundred years. I live in NY, and a stack like the one shown will air dry to around 12 - 14% MC by Fall if I mill it in the Spring. After that, I bring it in and dry it in a dehumidification kiln I made, from plans several years ago in FWW. With it, I can dry about 275 BF in a load down to about 8% MC in less than 3 weeks, for a cost of about $20.

Any quality moisture meter is better than none. I have a Mini-Ligno that meets my needs and seems accurate within 1 - 2%, which is good enough for me.

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[Joe Shinall]

John, that's a nice stack you got there. I am thinking I'm gonna build a makeshift "carport" design so there's a cover on top but not draped over the ends or sides. The humidity is a huge factor here, and so is the rain. If I didn't cover it with a piece of corrugated metal like you did, the wind and rain would just keep it soaked. I wouldn't mind if I had trees like you do but I have none in my yard.

Thanks for the picture, and do you happen to still have those plans for that dehumidifcation kiln? Or know where I could find them?

[Danny Hamsley]

I can air dry cherry, walnut, yellow poplar, and maple in about 4 - 5 months in Central Georgia down to about 15% moisture content. It would take a little longer if the wood was sawn and stacked in early summer, but even so, it will dry faster than you think. Oak, on the other hand, has to be dried slowly, and the higher humidity will allow this. It takes 6 - 9 months for red oak to air dry here, almost twice as long as the cherry and walnut. White oak dries even slower taking about 9 - 10 months. I cut and stacked some 4/4 and 8/4 quartersawn white oak on Jan 1, 2010. In Jan 2011, the 4/4 was about 14% but the 8/4 was still 20 - 22% after one year. But, it dried very nicely with no checking or splits, which is the goal!

Do not put a fan on any oak. That would lead to drying rate that is too fast, and bad things will happen in oak, particularly white oak. Low and slow is the way to go. Many other species like the walnut, cherry, maple, and yellow poplar can stand drying rates twice as high as the oak. The "Drying Hardwood Lumber" should have charts on maximum daily moisture loss that each species can tolerate. If you will be drying a good bit of wood, a good moisture meter is a must. I have a Wagoner pinless meter that works great, but it is about $400, so that may be more than you want to spend. You can get a decent pin meter like a Delmhorst for about $150. I have a Delmhorst J-Lite, but I find the pins to be aggravating.

If you head over this way near Perry, GA and need some wood, send me a PM!

[John TenEyck]

Joe, the plans for the kiln are in FWW #91, with a correction for the wiring diagram in #98. Here's a link to a few photos of the one I built from these plans. //https://picasaweb.google.com/JohnTenEyck54/Drier?feat=directlink (https://picasaweb.google.com/JohnTenEyck54/Drier?feat=directlink) Cost was about $300, since I already had a dehumidifier and a big squirrel cage fan. It's in a corner of my basement shop. Other than taking up valuable space it's great. Very little noise; no smell whatsoever since it's in a sealed box and the only thing coming out is water. The controls are all automatic - just measure the water removed daily and adjust the humidistat accordingly to stay on the drying curve. I've dried over 3000 bf with it to date. And since the temp. is only 110 deg, walnut looks just like air dried. The only negative is that it won't dry up the sap pockets in pine, since the temp. isn't high enough. But I don't use pine anyway, so it's no issue to me. Anyway, if you've got the space and have a source for getting green or partially dried lumber, this drier is a good option to get kiln dried lumber. Happy to answer any questions if you go forward.

[Joe Shinall]

Danny, glad to know you are dealing with about the same humidity as I am and having good results. And I will definitely get with you if I happen to go near Perry. Im always needing more stock! I won't be doing much oak. Mainly cherry, mahogany, chestnut, and maple.

Thanks John, I really like that and think I may be building one of those or a solar kiln. I've done a lot of research on solar kilns today and I have most of the lumber in 2x4's laying around and I have the perfect spot for it. I think that may be the route to go. It at least looks fun to try. I probably will do the dehumidification kiln as well for smaller stuff.

Anyone ever built a solar kiln?

[Howard Acheson]

John TenEyck has answered your questions. Follow his advise an you will have a good shot at ending up with nice, useable wood.

[Danny Hamsley]

I am going to build a solar kiln as well.

[Cody Colston]

Anyone ever built a solar kiln?

I'm building one that is almost finished. I still need to build a plenum, install the fan and stain the outside. I sized mine to hold 300 bft. A solar kiln is about as fool-proof as wood drying gets because the wood is "conditioned" every night as the temperature drops and the humidity rises. It's also a great place to store lumber while keeping it at a low MC.

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I based mine loosely on the one from American Woodworker Magazine http://americanwoodworker.com/blogs/projects/archive/2009/09/29/solar-kiln.aspx

The critical element is sizing the solar panels to the kiln capacity...1 sq ft of solar panel for every 10 bft of lumber capacity. The angle of the roof is based on the latitude where you live plus up to 10 degrees to help during winter drying.

In addition to Dr. Wengert's "Drying Hardwood Lumber", Bruce Hoadley's "Understanding Wood" is also a valuable source of wood knowledge. There is an incredible amount of misinformation regarding wood characteristics on woodworking forums and those two publications will correct most of it.

Dr. Wengert is also the in-house expert at the WOODWEB "sawing and drying" forum. He will generally answer any questions posted there and will also respond to e-mails. In addition, there is a ton of info from him in the "Knowledge Base" there. It's become a regular reference library for me.

[Joe Shinall]

Thanks guys for all your help. I have really got some good info and have gotten down the right path to being able to start doing my own lumber.

Cody, that is precisely the setup I was looking at. I saw how alot of different ones have the roof lift off but I don't have the luxury of having someone around to help me take the roof off so was going to make it hinge like yours as well as the front. What type of panels are those on the roof. Are they just clear corrugated plastic panels that you can buy at big box stores?

What type of plywood did you use on the outside and inside and how thick is it?

[Cody Colston]

I got the solar panels at Home Depot. They had two types of clear, corrugated panels and these are supposedly UV resistant. (Sun-Tuf Panels?)They were around $29 each for 12' long panels. (I cut them in 6' lengths for my kiln).

The outside sheathing on my kiln is 3/8" beaded plywood. I intended to get T1-11 plywood but the stack didn't look like very good quality. The stack above looked better so I got sheets from it, not realizing it was beaded siding. When I got it to the truck and realized what I had, I kept it rather than go through the hassle of swapping it out.

The inside sheathing is 1/2" PT plywood and all of the framing is PT lumber. For the floor, I used two layers of 1/2" PT plywood with a layer of 4 mil plastic in between. There's R-13 insulation under the floor and in the walls. I'll also staple a layer of clear plastic to the underside of the roof framing to create a dead air space there.

I haven't totaled up the cost but it will probably be around $1500 by the time I'm finished. My kiln is 4' x 11' outside dimension with a 41" high front wall and a 7' high rear wall. I can dry 10' long boards.

[Scott T Smith]

Scott, he does user anchor seal on the ends before transport. It's good to hear you say that, because I didn't know that was needed until he said it and then that solidifies it. I'll pick up that book and see what I can find.

Can you recommend a good moisture meter by chance(reasonable cost but still good)?


Joe, there are several quality meters. Most kiln operators use Delmhorst meters, and I like my Merlin pinless meter too. Lignomat and Wagner meters have a good reputation too.

You will find that meter accuracy varies above the fiber saturation point of lumber (around 32%); at the higher MC%'s the only really accurate way to measure MC% is to weigh the boards. However, this is not really required for a hobby dryer.

In addition to Dr. Wengerts book, the USDA has a host of manuals available for free (download); but they can be tenacious reading at times.

Howard is spot on regarding not putting green wood in an attic. Once it dry's down to 25% or less, it is safe to do so.

Re solar kilns, there are a lot of plans available, and these are a great way to go. If you want to dry in larger batches (1200 bd ft or so), the plans by Virginia Tech are generally considered to be the ones to have. Virginia Tech also offers a short course in drying lumber with a solar kiln, and if you're going to seriously pursue drying I would highly recommend the course, even if you build the smaller FWW based solar kiln.

[Joe Shinall]

Thank you Cody. That is just about what I had in mind and sounds like a great way to go. That is pretty much the size I was looking at too. Thank you for your help.

Thanks Scott, I did see the Virginia Tech write up and was very impressed by what they built. I am going to keep on reading up on this before I start, but I am pretty sold on this solar kiln idea.

[Cody Colston]

Joe,

I also framed in four vent openings in the rear wall of my kiln but they are covered up with the interior sheathing. I'll drill holes in the corners from the outside and saw the sheathing out on the inside then cover with screen wire. The vents are used to regulate the heat and humidity although they can be kept closed. It just takes a bit longer to dry a stack.