my boyfriend and i built it together, its actually a lot bigger than it looks. we made it out of plywood, which we now know was a mistake, so i had to cover it with picnic table cloths, which is why your getting a view from the top... on the top is a big peice of plywood (we took it off so i could cover it with a table cloth) im not sure if i would go this route again with an enclosure, BUT it gives my big girl something to roam around with
How many square feet? With some info, someone here may be able to estimate how much more heating you'll need. Covering it can help with both heat and humidity. I like CHEs, but I've heard that black light bulbs are much more efficient. Personally, I like to use a larger amount of smaller wattage CHEs to get more control over the gradient, as you can only lower a high wattage CHE to a certain height before it is too hot (ie. going up in wattage doesn't help much because you won't get much larger of a heat gradient out of it). I switch mine around depending on the time of year...when the house is warmer in summer, just the lights are enough, but most months of the year I also need the CHEs.
I wonder how long until she wrecks the nice stuff you put in lol? A picnic table cloth may not be sturdy enough long term...I'd go for pond liner (black plastic, seasonal), very heavy duty shower curtain liner (clear), or shower pan liner (gray plastic, thicker than pond liner I think, which they will cut for you at home improvement stores). Is the plywood just an issue with humidity, or aesthetics? Yes, you do need a liner with any sort of wood when using moist substrate, but for aesthetics, painting the plywood could help. You would have to let it air for quite awhile though, so of course that means a move for the tort. Good luck!
Yes it could, but personally I'm not a fan of any type of heating from underneath, for many reasons. A lot of people are moving towards the waterproof heat tape though. Some simpler ways to get more bang for your heating buck are raising the enclosure height (higher ambient room temp as heat rises) and to cover parts of the enclosure (also great for humidity).