This time of year with the heat running the house the interior air dries out, which makes keeping the humidity high in a tank even harder. I've been fighting chapped hands for a few weeks since the relative humidity in the non-herp parts of the house are under 10%.
I have my boas and pythons in a separate bedroom with the door closed since the rest of the house is fairly cool; between the heaters for the enclosures and a small chest freezer it stays toasty in there.
I also run an air filter/sanitizer in that room 24/7 with an 8-oz deli cup full of water set so the moving air from the air sanitizer flows across it. It increases the humidity in the room, but not so much that mold is a problem. Call it a poor man's humidifier but it does work.