That picture was my original build..I have since modified it after researching info on keeping the humidity up.
Adding sphagmum moss as and underlayment and closing the top of the enclosure with glass keeps the humidity at 80-85%. It was a rough time fighting to keep it up, but now, I have a handle on it.
Will post a pic of the re-done setup which includes a 2x4 glass terrarium added onto the wooden enclosure.