I whole heartily agree 23% is at least 1/2 of the humidity one should have in the home. I wouldn't be able to live in that dry of an environment. All wood based flooring products come with instructions for installation as well as the humidity levels that should be maintained for warranty purposes. 55% to 60% is the humidity level for wood products, flooring to furniture. With the AC on (if applicable) in the summer the RH should be maintained around 60%, without it can get as high as 99%. Even at 60% your RH is dropping 37%, of course the floor will cup, no doubt. Even if your vapour barrier above the concrete is not sealed 100% which is tough to do, the main contributor is that huge drop in RH in the building envelope. Control your relative humidity at 55% to 60% and I don't think you will see anymore cupping next winter. By the way the first thing we do when we open packages of flooring is throw out the warranty instructions for installation, to small to read anyway LOL. All wood flooring products including laminate have different acclimatization procedures. Was the flooring acclimatized if not rectifying the problem may to be to late. As brickeyee stated the original tree affects acclimatization. While I'm at it an FYI for all, the softwood products will be affected far more than hardwoods by moisture changes. That it why one will see more hardwood based antique furniture than pines, thus the huge prices some pine antiques demand. This post was edited by SouthernCanuck on Wed, Jan 9, 13 at 12:14

Thank you for your responses! I feel kind of desperate. To answer your replies... This is an older structure so we can assume there is no vapor barrier in place. When the problem first occured we removed some boards and found the concrete to be drier than the air's RH and wood (where it buckled)... We had one installer and the one supplier's rep that came out, they said prior to pulling up a buckled plank that they were willing to bet that there would be a large trace of water moisture underneath -- which was absolutely wrong. There was nothing and the concrete was tested immediately and shown to be dry (they did the testing)... using a moisture reading device that was driven into the top of the wood and concrete (separately). Interesting to hear about expansion, esp along the width of the engineered planks. How would you go about adding expansion joints?? Could they be added to the field?? Recall, this is a glue-down floor. The installer keeps saying "no" because it is tongue & groove... but what does that matter if it is glue down? Are there special saws for cutting expansion joints into a slab? Two of the open space rooms are large with almost 40 ft across the width (perpendicular to the direction of the planks).

We just had BR-111 brazillian cherry 5/16 installed on a slab. This was the first time this flooring company had installed 5/16 solid wood. The 2nd day after install floors started cupping just as pictured above. Some areas were worse then others. They sent out one of the flooring inspectors and he measured for moisture. Everything seemed fine and he could not figure out any moisture issues. The next day the owner came out. He brought out commercial dehummidifiers. He kept insisting it was moisture although no proof. My husband issisted on a qualified wood flooring inspector. He was to come the next day. The owner of the flooring place left. Less than 2 hours later he called on the phone and said he was sending some guys out to pull up all 1000 square feet of flooring in my whole downstairs. What was the problem??......... They had used the wrong glue. BR-111 rep said they had a new specific glue for this flooring on a slab. Flooring company had just assumed they could use glue that they usually used on all hardwood. The areas that were the worst were the areas that they had done the second day(thay were here 2 days laying floor) on the 2nd day they used a glue that was more like honey consistincy. These areas were really bad the flooring that was layed the first day did not look near as bad. If they had not changed glue the second day We may not have noticed. The other glue would not have shown the problem so drastically right away. it may have taken several weeks for the other areas to start cupping. This is the information that the certified inspector told the owner of the store. Needless to say he had 2 office personel out at my house tearing up 7500 worth of wood floor in there dress shirt, kakis, and dress shoes. They re-installed a couple of days ago with the glue from BR-111 and so far no problems. What a hassel it has been and I am installing a new kitchen.

I'm sorry, I didn't see that, yeah polystyrene is the foam i was talking about. It looks like you already have insulation. Capillary action is dragging water right under that whole floor. That looks like a damp corner outside where you have brick. So dumb I missed the water creeping right under your door threshold. Either you have a bad door pan or the door pan has no place to drain to. Either water is coming down the outside wall and going under the door, or water is pooling up in the brick patio and working it's way in. The solution to fix the patio surface is similar to a shower basin. If the flashing is all good around the door, you might need a little catch basin in the patio outside the door to shed water away from the door.