With any wood installation, the interior of your home, needs to be kept at a fairly constant temperature, and humidity. Failure to do so, will reek havoc on any wood you install.
have been warned about large humidity variations there
Ya, so what?:lol:
That is outside, not inside where HVAC systems are suppose to be installed and operating.
What did they do before HVAC?
They dealt with gaps in the winter, because most wood floors were only installed during the summers and high humidity.
If they installed it in the winter, gaps were left on purpose for the swelling of the wood during the summer, so buckling would be reduced.