I already replied to your e-mail, but I'll answer the question here as well.
Reflectix is an approved moisture barrier so I'm guessing it will work. Make sure to seal all the edges with foil tape and allow plenty of time for the adhesive on that tape. I don't think you'll need to seal it with anything else.
>>An 8' run was stupid. Why didn't anybody tell me?
When you first posted on this forum I was under the impression that the basic shell of the rack was already built. Did not seem worth mentioning it was too big at that point.
At any rate, let us know what your plan is with the remaining material and we can give you advice. No sense to rebuild it more than once.
Don't sweat it, it's happened to me...
I was in the process of building a unique rack design for venomous many years ago. About halfway into the project I realized the idea was horrible and scrapped it.
Part of the wood became a bearded dragon cage. I litteraly did not have to make one cut, even the frame for my false ceiling.
The secure door for the rack became the door for a hatchling rack.
The rest of the wood was used to built just a "normal" rack for the hots and all I had to build was a secure door that locked to the front.
What I'm getting at is that these things have a way of working themselves out.
-----
Current snakes:
0.2 Gonyosoma oxycephala - (Silver/Yellow)
3.3 Gonyosoma oxycephala - (Green)
2.1 Gonyosoma janseni - (Black)
3.3 Gonyosoma janseni - (Black & Tan)