Our house was built in 1860. Basement is 5 ' tall, encapsulated with spray-on insulation over field granite walls, fire retardant over insulation, and 6 mil poly with tape over dirt floor. Great sump system with battery backup/charger, and drains feeding to sump pit. All works perfect ...... but just a little damp from condensation. Furnace with exposed and updated piping keeps it toasty when fall/winter hits here in Maine. Use this space for storage and utilities only (furnace, panel, plumbing, etc).
So I placed a standing dehumidifier in basement, direct feed into sump pit. Humidity was 70% at start, and easily have it down to 55% now (digital readout on dehumidifier).
But when I look up at floor supports running across ceiling of basement, the logs are all original (1860), some of which even have bark on them ! These timbers have seen 155 years of humidity ...... and I don't want to disrupt them if they have already lasted since the Civil War. Proper supports and joists have been added over last 100 years, so structurally very sound.
Any thoughts on the appropriate humidity level to shoot for ? TC Hafford Basement Systems recommends 55%, but that is with a more modern structure with processed lumbar. The basement "feels" great at 55% humidity now, and it is easy to keep there (and there is no condensation anywhere.)
Am I doing damage to the old timbers in some way ????