Q: One visitor asked, "We had a very uneven slab when we started building our home and put 80% hardwoods in the home. The concrete company floated the downstairs extensively and then put the black tar stuff and plywood down before installing our nail down hardwoods which are red oak. It has been 10 months and it is very cold outside (below freezing for a week now) the floors are crackling all over the house and it sounds like ice breaking on a frozen pond or wood popping on an open fire. What does this mean and why is it happening and should we be worried?"
Your floors are reacting to the change in environment/temperature. They have not yet been through a complete cycle of climate change. It is said that it takes a year or 2 for wood floors to become fully accustomed to the home in which they are installed. I suspect with the cold temperatures, the tongue and groove joints are changing slightly and as they pull away slightly from their original position, it can make this cracking sound. Especially if the milling of the joints is very snug. I would suggest going to Radio Shack and purchasing a hygrometer. Very inexpensive device that will give you a digital readout of the temperature and relative humidity in the room it is placed. Place it on your basement floor and leave it for half an hour and see what your readings are. Try to keep the temperatures to near 70 F. at least, and the humidity between 30-40%. I wouldn't be concerned about these noises just yet, unless you start to see noticeable physical signs of change, such as large gaps opening up, or boards starting to cup (raised board edges indicate expansion and a moisture problem). A couple of years ago I noticed rather large gaps in a few spots on my 70 year old oak strip. I had never seen such large gaps in this floor. I got the humidifier running and the gaps closed.
I have heard of this situation a few times before, but have never heard of any catastrophes from it.
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