I am not sure the golden rod really does reduce the humidity,as it only raises the temp inside by a degree at the most.
I gather it works by raising the dewpiont of the metal as mentioned above.
Regardless,I have a dehumidifyer in the basement and keep the whole lot at around 50%.
It remains cool year round.
My understanding is large sudden swings in both temp and RH are the things to avoid for both timber and metal.
I also have a small extractor fan on a timer to slowly turn over the air in the room,mold will not grow if there is air movement I am told,although it probably wouldnt below 60%RH anyway.
