Guys, I'm sorry to back up on the conversation but this doesn't make sense.
Steph, if you get 30% from frequent misting, you're "normal" value should be 5% or less which is almost impossible. 30% is almost desert like!
The usual values for a house are 50%. If you live in a more humid region, this value is higher. I checked a few websites and seems that RH values for today and this time of year in Pennsylvania are around 80%.

There's a couple of hypothesis, whether your hygrometer is broke or you have the enclosure in an air conditioned room. If you don't have AC, before making any decision to switch to sterilites, try measuring with a different hygrometer.

Whichever is the result, if you still want to move to sterilites, a small word of advice: create an enclosure exactly like you would do and "use" it for a week without the snake just to make sure you don't get mold and fungus with that amount of ventilation. I got them in less than a week.

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Wish list: Blue Tongue Skinks and Uruplatus =)

I agree with Ricardo:check your humidity with a different hygrometer.
Also, what type of substrate are you using? Some hold humidity better than others.
If you have an aquarium with a screen top, try covering a lot of it with a couple of pieces of plexiglass. With a few different pieces, you can open up or close off more areas as needed.
If you decide to try sterilite boxes; don't put holes in the lid. I recommend putting 2-3 rows of small holes on the short sides of the box. Put them along the top edge of the unheated end and along the middle/bottom (above the substrate level) of the warm end. Because the warm air rises, it will have better air circulation this way. You can try it out without the snake inside for a while and see if you need more holes or not.
Here's an example with one of the baby boxes I'm planning to use:
The first pic shows the placement of holes on the top edge and the second shows where I put them on the lower end. (The holes are not as big as they seem on the pics!)




I hope that helps!

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Andrea

Thanks for the information and advice, Ricardo and Andrea... I am using a digital thermomter/hygrometer and it's new. It shows the temp for each side of the enclosure and the humidity reading. I have another one that I bought in advance for a new enclosure. I just opened it and tried it and it's reading the same... it shows "LO" when it reaches a humidity level less than 20%. I don't have the AC on this time of year. Any suggestions as to what other kind I should try??? I use paper towels as substrate. I know that's not good for holding humidity. I will give the plexiglass a try, Andrea. And if I try a serilite, I will "use" it for a week to make sure everything is ok. Thanks again!!!

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Steph
<t><
I am too blessed to be stressed! The shortest distance between a problem and a solution is the distance between your knees and the floor. The one who kneels to the Lord can stand up to anything!

1.0.0 Husband; 3.1.0 Children; 1.1.0 Corns; 0.1.0 BP; 1.0.0 C/BRB; 0.1.0 Rabbit

That's very weird. When you have sufficient ventilation, the humidity levels of the enclosure tend to normalize with room values. My geckos enclosure values go dropping to nearby 50% (or less due to heating) and my Bearded Dragon's enclosure needs some work to keep bellow 30% because it's always going up.

Can you take some readings around your house and exterior?

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Wish list: Blue Tongue Skinks and Uruplatus =)

Sorry forgot about substrate =)
You can try repti-bark alone or mixed with coco humus which should be much better retaining humidity. A large water bowl should help.

One thing that has worked nice for me is an area of pebbles on my gecko's enclosures. That allows me to mist that area heavily and less on the coco humus, water runs to the bottom of the enclosure and evaporates due to heating but in the meanwhile it keeps the humidity up without the bad smell of wet coco humus.

Also, take a look what theses guys did to raise the humidity level of their enclosures
http://www.thecarnivorousorchid.com/i/enclosuretips.htm

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Wish list: Blue Tongue Skinks and Uruplatus =)

The heating inside the enclosure could cause more drying than the surrounding room humidity.
If you have set your thermostat to lower the temperature at night, you should notice that the humidity is higher at night when the temps are a bit cooler.
I use humus bricks (disolved) as a substrate form my Rainbows and my BP and they do very well. My husband uses paper towels in the chondro enclosure and he can also keep the humidity levels nice and high. But in winter he's covered quite a few of the ventilation screens.

I think the problem is how much moist air you're losing out of the top of the tank.
Good luck!

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Andrea

Thanks so much, Ricardo & Andrea for your help. I've been playing with the pexiglass on the top of the aquarium along with dropping the temps at night to 75-80F. That seems to be helping quite a bit. I'm getting the humidity to 38%. With misting I'm able to get it to 50-60%. I will also try a different substrate - one that you've recommended. I really like the idea of the pebbles, Ricardo!!!

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Steph
<t><
I am too blessed to be stressed! The shortest distance between a problem and a solution is the distance between your knees and the floor. The one who kneels to the Lord can stand up to anything!

1.0.0 Husband; 3.1.0 Children; 1.1.0 Corns; 0.1.0 BP; 1.0.0 C/BRB; 0.1.0 Rabbit

You're welcome =)
If you feel that the screen won't rust (it shouldn't) you can also try to place a wet cloth instead of the plexiglass. Not only you'll be reducing ventilation but you're also introducing some humidity into the enclosure. If you add a drip system to keep the cloth wet, you can probably maintain a high level of humidity all time.

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Wish list: Blue Tongue Skinks and Uruplatus =)