How to use mirrors in basement?

Our home is newly built and the attic is well built with good strong flooring over most of it and a light switch and wall socket. But the fiber glass insullation on the rest of the attic floor and sides is not covered at all. I want to cover the fiber glass with a vapor cover without ruining or damaging the insullation. The reason I want to cover the exposed insullation is so I could store my christmas ornaments in the attic since there is room and a flooring. But I would like to be able to breath when I do so. The space is adequate and well lighted. I would also like to sweep and spray to keep spiders out so they don't take over. Does this sound like a good plan? Or would you not do it if you were me?

Hey Guys, my basement is currently unfinished and there is also a crawl space attached to the basement that is under the family room. This crawl space is about 5ft high and is vented to the outside with 2 vents. It just has a stone floor right now. My intentions are to finish the basement and I would like to use the crawl space as storage. How do I finish off this crawl space so I can close off the vents? My idea is to lay plastic over the stone and then build a wooden floor over the plastic and stone, seal the vents and insulate the walls. Will this work or should I do something different?? Thanks in advance!