Hard to tell for sure without a close look, but the roofing / waterproofing material looks like TPO, a single-ply roofing membrance. It is not made for direct traffic, so appears someone has installe ... read more
The best move would be to simply make sure the existing vapor barrier product is installed properly (flush to ceiling below) and add blown insulation over top to to get the best R value and at the lea ... read more