Hello,
I have many questions about our new maple hardwood floors? They were installed in late June, a few days after being delivered to our home. Weeks after installation several pieces had to be replaced due to cracks but I continued to see more when the sunlight shined on them. The installer felt there were too many cracks and now cupping. High humidity levels were suspected. The manufacturer's salesman measured the humidity of the wood and the ceiling beneath the floor in the 5 foot concrete crawlspace and is sending an independent inspector to evaluate the situation.

We reside in Delaware. We keep our AC between 72 and 73 degrees but the humidity levels in the house are around 60%, sometimes a little higher or lower. What is baffling to us is that we have had hardwood floors over the years and humidity was never mentioned? Some regions in the country did not even have AC and I'm certain the humidity was more than 60% on many days and there were never any problems with the wood flooring?

Must humidity levels always be measured before wood floors are installed or even considered?

Is 60% humidity too high?

What causes a hard wood like maple to crack?

Thank you

How and where was the wood acclimated? Was it dry at the time of installation?

The boxes of wood were stacked on the floor inside the house for 2 -3 days before they started to install them. Is the question about the wood being dry?
The weather was extremely hot during the install. We left town for a about 9 days the day after the floors were completed but we left the AC on 76 degrees. We were not monitoring the humidity level at that time but later this summer the humidity meter registered around 60% at 72-73 degrees.

So the HVAC was not on during installation? If so then you crank up err down the AC and now your shocking and stressing out the wood. Prolly no one even pinned the wood and subfloor to start with. AC is a de-humidifier.
Unless the wood is local you don't have any idea what the moisture content is at install, it coulda been to dry in which case a couple days in a box won't do anything at all acclimation wise cept for temperature.

Sorry if I missed this but is it solid wood or engineered hard wood? That might be what made a difference in other places not being as susceptible. I also grew up in a house with solid wood floors and they had no issues with all kinds of elements.we are in hell now with the engineered.

Granted engineered is a more complicated process than just milling out solid but it is made to weather the greater fluctuations in ambient temp and rh if it is made correctly. Mine is a 30 year old bruce 3/8 3 ply and has not had any delamination, just cracks. But then the cracks here are caused by low rh, which is not a manufacturing issue, only delam is. You can also get cracks from excessive movement, dry cupping ect. Crawl spaces are notorious wet spaces that can wreak havoc on floors.

you seeing cupping now because you are drying out the top of the board with the heat and the bottom is being kept higher moisture because its over a craw space. either humidify the interior or dry out the crawlspace. you have to have a balance above and below should be similar.

Is this the case for all hardwood floors? I'm noticing some cupping on my floors as well, which are over a crawlspace. It's not severe, but still a bit noticeable. Would additional insulation under the floor help? My crawlspace is quite large, drying it out could be a major pain.

Insulation controls heat transfer. The first thing to do is control the air transfer by sealing the penetrations between the crawl space and first floor. If the crawl space has a dirt floor then that should be covered with sheets of poly that extend up the walls. If the crawlspace has excessive moisture it will eventually do harm to framing in addition to your hardwood floors.

Yes all wood floors should be kept at normal r/h ( 40 t0 50%) year round for optimal performance. Too dry and your floor will contract, too humid and you floors will expand. Too much of either is not good. Most people dont think about that a single piece of floor can have different moisture content as you move through the piece. Cupped floors will often read 12% on one side (the one closest to the source of moisture) and 5 or 6 on the other side.

Thanks - do you know how much is "too much" moisture?