A guy at the lumber yard in Tacoma told me to quit stacking my 2x4s flat on the concrete
I had a whole bunk of 2x4 studs sitting flat on my garage slab for about 3 weeks while I framed out a shed. A guy named Dale at the yard in Tacoma asked where I was storing them and when I said flat on the floor he just shook his head. He said the bottom boards wick moisture straight out of the concrete and I'd end up with crowned and twisted lumber, turns out he was right, 6 of my bottom row were bowed bad enough I couldn't use them for plates. Now I sticker them on scraps and keep them off the slab. Anyone else lose a whole layer like that or am I the only one who didn't know?
Used to figure concrete was dry so who cares. Lost a whole bottom row same way you did. Now I keep everything up on scrap 2x4s and never had the problem again.