Hi,

Would someone please explain to me, how does a 3/4" solid maple hardwood expand if its nailed down every few inches using 2" cleats to a 3/4" OSB subfloor ?

I did create enough room for expansion and allowed the wood to acclimate. At least 1/2" (as i raised the drywall via cutting it and hiding the raise by my removed and re-installed baseboard) just about everywhere, except for a small couple of places, where i was unable to do so. (example stairs)

Also at what force will it expand ? Say for example it hits some drywall, which will be much softer than the hardwood itself, would it not dig in, rather than buckle the floor ?

Anyway just trying to understand the ins and out of expansion.

Wood expands and contracts due to changes in its moisture content. This is related to the changes in the relative humidity. Wood expands and contracts across its width and neglibily along it length. The expansion gap that is parallel to the flooring is there to protect walls, pipes, etc. Which could be damaged if there was severe expansion. If wood wants to expand it will.

Understand wood expands. But if its nailed, what's it going to do ? buckle on itself at the first plank next to its side? Cos that's not going anywhere in a hurry.

Never had wood flooring before, so trying to understand how exactly its going to expand on itself... My AC will remain on at all times at 77, unless it breaks down, in which case i'll be getting the techs out ASAP to fix.

The only real outage i could be subjected too, would be a Hurricane and major outage of a week or so, (which has actually happened back in 2005 Wilma) Power was out for a good week. Would a week of being out of power enough to ruin a floor in a humid climate ?

Before wood flooring is installed it should be acclimated to the midrange of the moisture content for the geographical location where it is being installed. This is done so that the floor will neither expand too much in the humid season or contract too much in the dry season. If you maintain a constant humidity level within the house year round and have acclimated the flooring to a moisture content that is in equilibrium with this humidity level then the floor should neither expand or contract. If the floor was really dry and had a low moisture content when it was installed then it would expand as it takes on moisture. If the floor had a high moisture content when it was installed then it would shrink as it looses moisture. The expansion and contraction don't happen instantly....it would take some time for the dimensional change to occur. If the humidity was elevated for a long period of time or if the floor got flooded the boards in the center of the room would expand against and buckle upward as they pushed against each other. The boards around the perimeter would expand toward the expansion gap. Just as acclimation does not happen in a specific time period and is a factor of the wood's moisture content when brought in and the household's relative humidity, the time it would take for wood at a certain moisture content to buckle with a spike in humidity is not specific either.