First of all, all ends should be sealed with either a wax or paint coating to minimize checking. You need a flat base with support under the lumber and stickers between each layer. It needs to be covered on top but with air flow through the stack, either from natural wind or using a fan. The old guidance of 1 year per inch of thickness generally applies for air drying. A lot depends on your location, air flow, humidity, etc.

 

If it is white oak, 2 years is the rule here (Maryland). Red oak is more porous like a straw. Hard maple can take 2 years also.
After letting it air dry for 6-8 months and you you have a building that is fairly tight, that you can sticker the wood, with a dehumidifier, you may be able to reduce the time a lot. The slower you dry it, the more even it will dry and the less it will check. It is an interesting balance, if it gets wet - for example - and then dries, it will dry faster but it will check in days. If you put the wood with a dehumidifier too early, the wood may not dry thoroughly and crack. There is a whole science around this.

There is one thing that you want to be aware about air dried wood. Inspect the wood very carefully, air drying does not kill any critters that may be in the wood. Heating the wood to 120 (F) for a week after it has dried, is ideal.

 

The general rule I have always heard is 1 year plus 1 more year for every inch of thickness. However, from experience, I know that I can dry 1 inch walnut in about 18 months.

Part of the issue is when was it harvested. In the winter the natural moisture content of the wood is much lower than it is in the spring or summer. I think the perfect time to cut down a tree is January if you plan to air dry the wood.

 

I have a mill that air dries reasonably close by. He leaves the log to sit for a year or two before cutting, then lets it dry after cutting for a couple of years. The last red oak I got from him earlier this summer, he had dated 1996. I had a mill that kiln dried and he would cut first and air dry for a year and then put into the kiln (120 (F)) for up to 30 days. I would say the you are very accurate about when you cut a live tree. A good moisture meter is required. When I get lumber it is between 8-12 % MC. After sitting in shop, it is 1-2% MC at the highest.

 

There is a member on another forum that sells plans for a DIY wood kiln. I can't attest to how well it functions, but it may be something worth looking into. If interested PM me and I will point you in the right direction. (I won't post it here because I don't want to advertise his business, or another forum here…)

 

Thanks to all for the info and suggestions.

 

I have a solar kiln patterned after #1 here: http://www.woodweb.com/knowledge_base/Solar_Kiln_Designs_2.html and it's awesome. Cost next to nothing to build and will dry 2" wet wood in a month or two depending on ambient temperature and sunlight hours.

 

Here is a link to that LJ member's plans

http://cgi.ebay.com/Wood-Dryng-Kiln-Plans_W0QQitemZ280576277263QQcategoryZ84011QQcmdZViewItemQQ_trksidZp4340.m263QQ_trkparmsZalgo%3DSIC%26its%3DI%252BC%26itu%3DUCI%252BIA%252BUA%252BFICS%252BUFI%26otn%3D10%26pmod%3D280563062560%26ps%3D63%26clkid%3D4948850380591198384

 

Air drying wood.

The one inch per year rule is flat wrong. I have been kiln drying wood for 9 years. In ambient temperatures (>70 average in day) 4/4 Red Oak can dry to 14-15% MC in 60-90 days. 8/4 can take longer.

White Oak is a bear to dry and should be stickered properly, OUT OF DIRECT SUNLIGHT (shed) and with good air flow to have a good chance of properly drying.

Here is the Forestry service handbook for air drying lumber..

An example given it can take 70-200 days depending upon the time of year it is stacked. for Northern Red Oak.

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr121.pdf

Dr Wengert is a contributor to this paper as well as an authority at Woodweb.

 

Thank you, I will bookmark this. The times that I quote have worked for me. White oak has a membrane, so to speak, within the grain that makes the wood almost waterproof. This makes it just as hard to remove the moisture.

There are some commercial dehumidifiers that will work nicely in a homemade kiln. Some have heat as well. A word of note, If you dry wood too fast, especially for thicker stock, you can create a situation where the ends are dry and the center isn't. Moisture works a little like a rubber band, when it is moving, it tends to pull other moisture with it, if the band snaps, the remaining stays put. The same happens when you heat the wood, it changes. When a part of the wood gets down to a certain level of dry, it is less likely to move water - in or out.
Sometimes slow - if you can wait - is good. The slower you dry wood, the less the checking - unless it is under stresses from bends and twists.

 

There's some pretty good information here:
http://www.ehow.com/how_5624934_air-dry-lumber.html