Here is one thing I have done that has also raised the humidity in the at the plant level. I bought some clay orchid pots, the kind with lots of slits on the sides, and filled them with sphagnum moss. I soaked them in a bucket of water for about an hour and placed them with the orchids. I group four orchids around one "humidity pot" . I water these pots as needed to keep the sphagnum wet. You can see the moisture on the outside of the pots. This also allows me to have nicely soaked sphagnum at a moments notice if I need it. The only drawback is that they take up space that could be devoted to more orchids.
The whole set up is on grids above pebble trays.
I have found that the humidity about two feet above my growing table is 40%,the humidity at the level of the plants is closer to 50%. Now if I can only find a way to get it to 60% without using plastic drapes or a humidifier I'd be happy.
Judy