How to Dry Lumber
I recently explained how I saved a couple thousand dollars buying lumber. When we moved from Georgia back to Idaho, it became necessary to figure out how to dry all this stuff.
Ultimately, there are several ways to dry lumber – air, kiln, solar, and even by boiling.
I opted to air dry mine, partly because of how large the boards are (10-11 ft long) and partly because I am now quite limited in yard space. Air drying is also one of the better options here in the West where the climate is quite dry already. If we stayed in the South, air drying takes much longer and is probably not as effective in removing enough water content as the other methods.
Air Drying Basics
1. Ensure the Base Is Level
The most important aspect when drying lumber, regardless of the method, is to make sure the wood is stacked flat. To do this, I laid down 6 large boards/ties (4x6x48″) and made sure each was level. This became my base on which to stack all of the lumber.
The base also serves another important purpose, and that is to keep the lumber off of the ground. If you skip this step, then you can count on at least the bottom layer of lumber being ruined by rot, insects, mold, etc.
2. Clean the Lumber Before Stacking
I learned this the hard way. When reading about drying wood, all of the places I read failed to mention you should clean the wood of sawdust before you stack. My wood, like most freshly sawed rough lumber, was packed with sawdust. So in other words, I ended up having to unstack and then re-stack the entire pile. And in case you were wondering, moving a 1,000 bf of green hardwood by hand is a lot of work. (Thanks again John for helping out…both the first time and then the second time.)
Why is it important to clean the lumber of sawdust? If you don’t, the sawdust could start molding, which will then stain the wood. The stains can seep deeply into the wood and ruin an entire stack of wood. Or, depending on how you look at it, morph your precious lumber into a pile of cheap dimensional firewood.
To remove my sawdust, I used a broom and a metal brush. It worked pretty good. Doing it over again, I probably would have started with a pressure washer. I tried a hose, but it lacked the pressure to remove the sawdust caked into the thousands of splinters on each of the boards. If you use water, just be sure to wait a few hours for all of the excess water to dry off before you stack the boards. If you don’t, then mold will grow on the top and bottom of each sticker, resulting in streak marks/stains on the lumber every couple of feet.
Which reminds me. I should mention that some sources, even the professional ones, claim you should water/sprinkle the lumber if you live in arid climates. The idea is that since it is so dry in some places, like SE Idaho, the moisture evaporates too quickly out of the wood causing it to crack and warp. Sounded reasonable. Unfortunately, it created an ideal laboratory for mold to grow at each sticker. Thankfully, I spotted the problem soon enough, and, sigh, had to break the pile down, fix the problem, and re-stack.
Oh, and thanks John for helping me again. (If you haven’t been counting, that was the third time John and I stacked the wood.)
Did I mention moving 1,000 bf of wet hardwood by hand is a lot of work?
3. Create Air Flow Between Layers
The next most important step is to stack the boards so that there is adequate air flow between each layer of wood. To do this, use stickers. Stickers are basically thin sticks, often in the size of 1x1x48″. Some people use fence lathe, which also works well. I decided against lathe, however, because I worried there was not enough of a gap. For my stickers, I went to the Do-It center and asked them for their scrap stickers (which come with every stack of lumber they buy). They happily obliged since it helped them clean up some of their lumber mess. The stickers were all 2x material, but that was not a big deal for me. What is important is ensuring all of the stickers are the same thickness.
The experts say you should stack the stickers anywhere from 2-3 ft apart. Doing it over again, I would go for about every 1 1/2 feet. I had few layers that sagged a little because the gap between stickers was too wide. It’s also important to keep the stickers lined up. In other words, the stickers on row 8 should be in line with the stickers in rows 7, 6, and so forth.
Again, it is crucial each layers of wood is stacked level or you will have bowed wood. If there is a sticker that is thicker than the rest, all board layers above will warp and not dry flat.
4. Paint the Ends
Painting the ends of the lumber helps slow down the drying process at the end (end grain) of the boards, which prevents checking (cracks or splitting). You will still see some checking, even having painted the ends, but not nearly as much as you would leaving the end grain bare. For a point of reference, my boards only had about 2-3 inches of checking on each end. For paint, I just used leftover latex. There are commercial waxes you can buy that supposedly work well. I found latex paint did a pretty good job.
Some sources also suggest painting the edges. That might have helped prevent a couple of my boards from buckling. Hard to know. For me, the extra work and paint just wasn’t worth it. I doubt painting the edges makes that much of a difference and may in fact hamper the drying process since there is less exposed grain to allow water evaporation. Hmm, that’s an interesting thought.
5. Waterproof the Pile
If you are stacking your lumber out in the open, you need to keep rain and snow from falling onto the pile. I placed a tarp over mine. Just make sure that you still allow for air flow. Don’t wrap the pile so tight that no wind or air can pass through the layers of wood. Some water still found its way into my pile. I was worried it stained the wood. Thankfully, the water stains were not too deep and all came off when I planed the wood.
6. Weigh It Down
Make sure the top layers have enough weight to keep the boards lying flat. I threw on some logs and also was careful to use my least valuable wood on the top layers. I wanted my most valuable wood near the middle and bottom to ensure there was enough weight above to hold the wood flat as it dried.
That’s it. By the end of the summer, my 1″ thick lumber was dry enough to use. Note: in humid climates, it may take you up to a year per inch of thickness to dry. The lumber turned out great. A few boards were twisted and became firewood. Overall, though, I had very positive results.
Update to Post [Dec ’08]: I had to re-stack the pile a fourth time. Once the wood dried, I pulled out the stickers and stacked the boards directly on top of each other. This is an important step to help further encourage the boards to stay level. At least the 1,000 bf of wood was not quite as heavy this time since it was dry. Thanks for the help, Carl! (John, I understand your desire to avoid my calls.)
A Mouse in the House
As an item of interest, a mouse decided the wood pile was an ideal place for his home. The little rodent made a nest in one of my layers…and then proceeded to crap throughout all other levels of the pile. At least the mouse wasn’t a poop-machine like a cow or something. That would have really made a mess out of my wood, which would have really stunk. Ha! Okay, pardon the pun and the dry humor today.
A Free Drying Guide
If you would like a more in-depth guide or want to learn other methods of drying, check out this free guide created by the USDA.