Vinyl Storage

Help. I'm running out of space to store my records. I'm planning to put them in my basement now (in Ikea Kallax organizers). The temp is fairly consistent around 70 degrees F). The interior cinder block walls are painted and carpeting is laid down.
I am concerned, however, about possible damage by humidity although it doesn't really feel that humid. Should I be okay with this? Would a dehumidifier be beneficial in this case? Or is that just a waste of money?
It would have to be really humid to have any effect on the outer jackets or sleeves. The only concern I would have is flooding, a friend of mine just had a bunch of his albums get soaked. The vinyl was fine but the jackets are toast, maybe toast is a bad choice. But ruined is accurate. 
Does the basement have a sump pump? If not, maybe raising the shelves up on 4x4s could help prevent flood damage. 
Just put a portable dehumidifier in the room and set it to run automatically and have zero worries. Keep the albums 12 to 18 inches or so off the floor . (cinder blocks)
You have to be vigilant to keep mould from getting in the cardstock of the sleeves, and the paper inner sleeves then migrating into the grooves. I have over 8000 stored in the basement and have for a couple decades like this with out issue. It doesn’t have to be really humid as posted above. Its the CONSTANT accumulation over time that makes things musty/mouldy quick. Cheap dehumidifier is pretty inexpensive insurance and up off the floor will save from the rare and off chance of a foot of water in your basement should you not have a sump pump or it fails to start. Many people never check them and just assume they are in working order.