air drying lumber on garage wall rack?

Make sure you keep it well away from a cement floor or wall and air has to flow through the boards

Yes, you should have something on it to help keep it flat. It will take years and years to get it dry. If you ever plan to have it be furniture quality, it needs to be dried to 6-8% moisture content. That comes from kiln drying it. If you don’t kiln dry, best you’ll likely get is 12%. Something to think about. It would be disappointing to have a project go bad later.

Ufortunately, that’s one of the toughest ways to dry lumber. Enclosed buildings trap humidity. Years and years ago I stacked some green pressure treated pine in my garage because I wouldn’t be able to get to the deck project for a couple weeks or so. When I uncovered the middle of the pile it had mold all over it.

Air flow is the key, allowing the off-gassed moisture to dissapate. Although it mainly applies to larger stacks, you have to rotate the inner and outer sections of the pile to keep the drying at an average rate. And weight for flatness.

As far as 6-8% MC from air dried lumber, Arizona is about the only place you can get there by only air drying. Here in MN I’ve seen it get as low as 10% outside.

Are you air-drying it to preserve the color? I do that with walnut or cherry since they have the greatest color variance in air dry vs. only kiln dry. But even then I take it as low as I can get it outside then kiln it for the last few %. Stuuf like oak, maple, etc. – it doesn’t make much difference.

Martin, see my air drying fixture in my projects http://lumberjocks.com/projects/8342
With the proper setup and air movement you can do better than 12%.

-- Phil in British Columbia

Phil – I didn’t see that before. An absolutely great idea! Solves all the problems.

You can get air-dried if you wait, at least in Northern CA. I am about to put down a floor of black acacia which has been cut & stickered a bit over a couple of years, and it’s about 8% or so. It was dried & stickered in the house (I set the stack in the kitchen over a vent with weight on it, and built tunnels through the stack to push the hot air through it for two winters). B/c it was a year down at 1” thick when it went into the house, it didn’t crack or anything and it’s now ready to be put down.