help with ventilation in cage!!!

[burmeselover15]

so yesterday i went and got some melamine from home depot and had them cut it for me. i decided that 7ft10in was ok just 2 extra inches taken off and now the size of the enclsoure is going to be 94in.x30in.x24in. so the plexiglass i had would fit perfectly into the slats for the sliding glass doors. well know im stuck and dont know how much ventilation to have since this is my first time building a enclosure. i know it needs to be little but enough. im just wondering what u guys would suggest on how much ventilation. the ventilation is going on the back walls so yea. thanks ")

[Icicle]

For my Boa I have a hole cut out right in the top with a window screen covering it. it is 20" long by 10.5" wide.
And my house is 6' wide by 18" wide by 16" high and It been keeping my humidity around 70-85%

[razeraze]

I use floor vents so I can close them.