I understand the importance of relative humidity to wood. I live in southwest Idaho where humidity is never very high. The humidity currently is about 39% (in Feb.) and in the summer, it's in the 7% to 13% areas. My house is about a 100 years old & the subfloor is T&G red fir. I just brought home my new (unfinished) red oak floor last night (3/4" x 2-1/4"). Was wondering how long I should acclimate it to the house & fir subfloor, before laying it? From what I've read, I'm guessing about 5 to 7 days. Does anyone have any other thoughts on my situation?
Thanks, Deby

I'm not a pro by any stretch of the imagination, but testing with a moisture meter is really the only way to know for sure I believe. Also the subfloor and hardwood should usually vary no more than 4% of each other, 2% for exotics.

BTW, I'm a little confused about your summer humidity level; I would think the wood would be in that range, but not the air. Do you have a hygrometer in the room where you're installing the hardwood? I live on the "wet" coast, and it doesn't get very dry in the house even in the winter, usually 45-50% (but occasionally a little below 40), and in the summer it may go to 60% (we have forced air gas furnace/no A/C). Even if you lived in the desert, I doubt your humidity should be less than 25%. Maybe some one in the know will correct me on this.

The only way is a moisture meter. Humidity in our area is very low in winter 15-25%. Each home is different but we usually are safe installing at about 6% m/c. Again it depends on interior conditions as well. Time really doesn't matter, it is definitely what the meter says that is important.

Make sure you do at least 20 to 30 readings with the meter and average it out. You cannot tell by one or two readings. I'd install when it is in the median zone. Also HVAC has a large effect on the seasonal rh factor.