Just for the heck of it I took the hygrometer to the basement last night. We have a 3,000 fully finished (wall to wall carpeted) basement. 10 yr old house. No air was on in the house (it was cool outside) and it was a wet evening with sporadic rain. External humidity was 85-95% based on our electronic weather gauge (hubby's hobby).
The RH in the middle of the basement was between 55 and 61% based on a number of readings over several hours (it went up and down).
Is this too high? It didn't feel bad down there. Carpet doesn't smell. It was reading 50% on the first floor at the same time.
Wondering if a dehumidifier is necessary for just maintenance reasons and if so would it be ok to put it in the furnance room in the basement (with the door open) since that is where the drain from the sump pit is at).