Someone from my previous church reached out to me regarding their hardwood floor coming up after a recent install in their downstair's den. No signs of water, but humidity is high. Not much info below, but any guesses from those of you that do this for a living? I can ask her for more details if needed.

"Joe, do you know where I could have a piece of manufactured hardwood analyze/tested? The glue used for installation needs to be tested also. The floor came up after being installed on a concrete foundation. There is a lot of humidity, but no water has been visible. ______ _______ installed it. He has done my whole house over years. It was all hardwood. It look fine. This concrete issue is different. He wants to blame the humidity, which is high. It was fine with carpet for years. No problems, no mold, nothing."

Humidity CAN do it...i ain't know professional so maybe someone else will chime in with other thoughts...

Was the concrete sealed when he had carpet on it? I would assume yes if he had no moisture issues. If he didn’t take up the sealer it’s possible the glue is coming up because it can’t adhere to the sealer.

Could be moisture, wrong glue, wrong trowel (didn't leave enough glue). Your friend may need to get a sales rep for the hardwood manufacturer to look at it. The store that sold them the wood can set it up.

is the wood coming apart with the glue holding the bottom of the boards down? But the top surface is coming up. If so the install sounds ok but product is failing. If the boards weren’t allowed to sit in the room of install for a few days before install that can cause extensive expansion and contraction. Those flooring glues can also set real fast with higher humidity levels and form a skin that won’t adhere if too many rows are troweled down before the boards are placed.. They draw moisture from the air to cure.

This is all information contained in the instructions on the glue or in the wood packets if it’s engineered wood.

Is it a glue down engineered hardwood or a bamboo? I've seen problems from installers not using enough or right glue for the job. Installer could have used glue that had frozen prior to installation. Never ,never, never put hardwood or laminate in a basement. Tons of better and cheaper options than wood.

This is neither here nor there now, but she should have used a floating floor if she wanted a wood type flooring.

The thing about hardwood (Or any wood for that matter) and concrete, regardless of moisture, is that you have totally different rates of thermal expansion and you are trying to glue one to the other. So as temperature varies, then the two bonded pieces are constantly trying to break that bond formed by the glue.

Personally, I would never try to bond wood to concrete. I would have used a floating floor over a moisture barrier or build a wood sub floor that floated over a moisture barrier and then attached the hardwood floor over that.

There are several things that could have happened.
1. Moisture acted as a bond breaker or didn't allow glue to properly cure. Typically this happens on new concrete or if there is some specific water intrusion. But it can occur on existing slabs if there is a water issue under the slab and improper vapor barrier. I assume certain sealers or other materials could also cause a bond break.
2. Installation errors on glue application
3. Glue flashed over before wood was set in place which will result in flooring that delaminates from the slab.
4. A bad batch of product. A very large home builder has 30+ homes in Liberty Park where wood floors are coming off of slabs. 4 different installers but same glue. This is current for 2019.
2, 3, and 4 can all manifest together in my experience.

The wood that has popped up...is the glue adhered to the wood or the slab the most? Or the same? That answer will tell a great deal.

I can get you a name for a testing lab that was used in the Liberty Park issues. Also there are concrete moisture tests that I or other flooring people can run...test for vapor coming up thru the slab.

Humidity...what is the level? Any idea why it's high? Any wall leaks in basement...downstairs den?

Not enough details here to really tell, but it could be as simple as poor slab prep before the glue was put down.

Basement and hardwood = no bueno

Is it the traditional 3/4" stuff?