For my Tour Master, under the carpet is carpet pad followed by "Seamless Structurewood Floor Decking laminated to the Steel Floor Structure" As I read the diagrams, this Steel structure had foam insulation laid into the cavities and there is a galvanized steel sheet under it all.
I will try to attach an image from the factory brochure...sorry that did not work.
Look on page 16 of this link:
https://library.rvusa.com/brochure/2...rMasterWeb.pdf
Your Sun Voyager may of course have a different construction...
Chuck