Should I re-stack this batch of drying elm lumber (pic)?

In March -- approximately 3 months ago -- I had a small elm log milled into lumber. Recognizing that elm is notoriously difficult to dry without it twisting into pretzels, I still took on this project knowing that I'd likely loose a large percentage of it to warping/cupping/twisting/etc... as it dried.

(As an aside: this photo I found when considering the project and I googled "milling elm into lumber" gave me nightmares: https://wunderwoods.files.wordpress....pg?w=300&h=199)

But I had access to the tree for free and it was only around $60 to mill it, so I still went for it, and I'm glad I did. I had a couple of 9/4 slabs milled (bottom of the stack); most of the rest is 5/4, and a couple of odd thickness boards are mixed in higher up on the stack.

It is stacked in my dry basement. By dry, I mean the air is conditioned well -- in the winter, it is remarkably dry down there with the forced-air heating desiccating the air nicely; in the summer, the AC and a maxed out dehumidifier keep the relative humidity remarkably low. I realize it still has another year+ to dry before it'll be useable for anything. Two box fans circulate the air 24/7.

In the first week or so, when the wood was still sopping wet, before I had the fans set up, a little mildew showed up on the ends of the boards -- stuck beneath the dried anchorseal and the end of the board. But that was quickly stopped with better air circulation (and the moisture content rapidly dropped). But the length of the boards remain fungi- and mildew-free. I routinely inspect for any signs of bug infestation (none seen) and other problems. All seems good so far.

Except for one thing: these boards are cupping and warping as anticipated. This is leading me to wonder if I should be doing anything to mitigate this movement.

You can see the entire stack here. It is stickered with 3/4" thick, 1" wide pine stickers. The bottom is a foundation of cement block. A dozen more cement blocks are stacked across the top to add some weight.

So the question is: Should I dismantle this stack and attempt to re-stack it in some other manner to mitigate further movement, or has this ship already sailed and I should just let it ride, as-is?

This is a wide view of the stack:
Attachment 387832

This is the end view of the stack. The day I stacked it, the boards were all beautifully flat, horizontal, and parallel. As you can see, the entire stack is listing to the right ... and that list has slowly grown more steep every day.
Attachment 387833

Another view of the end of the stack:
Attachment 387836

As you can see in this close-up view, it isn't simple cupping along the growth rings that is causing this listing...it is some funky rippling that is indicative of drying elm:
Attachment 387834

You can see where the boards have separated from the stickers where they are warped ... all boards were in full contact with every sticker on Day 1. Now, not so much.

I don't think you will gain anything by restacking at this point. The mildew surprises me. What was the RH in the space when that happened? What is the wood's current moisture content?

Probably just needed more weight on the pile.

I think the ship has sailed make sure you get the moisture content right and hopefully you have left them thick enough to get the thickness you want with the plainer. You can always rip them at the peak of the cup to flatten them out but that has the downside of a gluing job or narrow boards.

Thank you all for the replies -- confirmation of what I already was thinking.

Silly me, I thought ~500 pounds of concrete block would be enough to keep this stack somewhat flat, but looking back, I knew elm was risky, and this just proved that fear correct.

When I first put the stack in this location, it was a few hours after it was milled and the wood was sopping wet. It coincided with a period of the early spring when we got some relatively warm weather, thus the heat wasn't running very often, nor was it warm enough for AC, so the furnace just wasn't circulating air very much...and I didn't have any fans on the stack. A week later, when I saw the mildew on the ends, it was effectively 'trapped' between the anchorseal that was coating the ends and the soaking wet wood. I immediately set a couple of fans on the stack, adjusted the furnace thermostat to keep the fan on 24/7, and did a better job monitoring the RH in the basement (and keeping it low). That intervention appears to have stopped the mildew in its tracks. The staining remains on those ends, but the moisture content is way down now.

I have a surface moisture reader (no probes) and it was reading in excess of 35% for the first couple of weeks; now it reads anywhere from 15-23%, depending on the thickness of the board that I'm measuring.

I think the majority of the movement is done, as the listing seems to have slowed, but I know some more might still result.

I'm relieved I wasn't already set on using this wood for certain projects, since it is becoming a bit unfriendly, but I'm still curious to see what I can do with it down the road.

This has been a remarkably different experience from the walnut that I had milled last year and stacked in my basement and garage; that wood has dried beautifully flat with ease!

Personally I would restack it.

Wood does not start shrinking until it dries below FSP (fiber saturation point), which is around 30%. So the recent movement is indicating that many of your boards have dried lower than that, which is to be expected.

It appears that your stack is too close to the back wall for proper air circulation. The rule here is that the minimum space between a green lumber stack and a wall to one side is equal to or greater than the sum total of all of your sticker thickness. Thus, if you have 20 layers of 3/4” stickers, your stack should be at least 15” away from the side wall.

The optimum weight per square foot to place on top of a stack of elm to keep it flat is around 250 psf.

Quote:

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Originally Posted by Scott T Smith

Personally I would restack it.

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So if you were to restack it, would you basically pull out each board, flip some so that the cupping and warping alternates through the stack, with one layer attempting to 'offset' the next layer, and so on, in an effort to regain some sort of level, straight stack?

Quote:

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Originally Posted by Jay Michaels

So if you were to restack it, would you basically pull out each board, flip some so that the cupping and warping alternates through the stack, with one layer attempting to 'offset' the next layer, and so on, in an effort to regain some sort of level, straight stack?

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Yes, that would be a good approach.