After 32 years living in a 'company' house built in 1927, we have discovered all the first floor hardwood flooring has been laid in the SAME direction as the underlayment flooring(which appears to be 8" fir with a couple of grooves running its length in the middle).

This winter, for the first time ever, we had used the small woodstove in the cellar almost continuously during the two coldest months. Now, there are gaps in the hardwood flooring, running the length of the flooring at four-board intervals, in all the first floor rooms. We already know this is the result of the changes in humidity, and we are hoping(against hope), with the onset of more humid weather, the hardwood floors will return to their original condition. HOWEVER, how can we keep this from happening again? From the cellar, we do have access to the underlayment side of the flooring above.