I want to be able to get around my attic without having to balance on the joists. I am thinking of nailing 1x4's on top of the joists (and therefore above the fiberglass insulation batts) with an inch between each 1x4. I was also thinking of putting plastic sheets down above the insulation and under the 1x4's to reduce air flow from the house into the attic. I will seal all the obvious air leaks around fixtures, plumbing, vents, etc as well.
My question is: does installing plastic sheets above the insulation pose any condensation risk?
Thanks in advance.