Drainage layer for UNPLANTED viv?

[LadyWraith]

Sorry to keep expounding on the bioactive topic, but I can't for the life of me find this one particular bit of info. Everything I've been reading about the subject is in relation to planted vivs where a drainage layer is necessary. However, I'm not using plants in my terrestrial snake enclosures. Literally just dirt, leaf litter, bugs, and maybe some wood pieces. I'll refresh the leaf litter as it breaks down. I've read that springtails (which I plan on ordering and adding to the mix) require the drainage layer for breeding purposes. Is this correct? And if the drainage layer is needed, will belly heat (I use Flexwatt) still work through the layers (90°-ish hot spot)? I may just need to experiment with the belly heat thing if you fine people aren't sure.