Covering Floors?

Hi Adam,
We’ve traced the flea issue to the upper level of our house, which has hardwood floors with somewhat large gaps where debris collects and we believe the remnants of the last tenant’s flea problem is still festering. We’ve tried vacuuming this repeatedly, spreading DE, and freezing them out but are still seeing emerging adults. Because I’m pregnant, we don’t want to use any chemicals. Since moving in, our pets have not had access to this area and continue to be kept off this floor. As we ride out the rest of whatever’s hatching, we were wondering about using construction grade floor paper to cover the floors (the stuff builders use to protect floors during construction) and sealing every seam and edge from wall to wall and corner to corner upstairs. Do you think this is a crazy idea for riding out the rest of the infestation? We’re hoping they’d continue to hatch but be kept under the paper and eventually starve. We could leave the paper sealed up for months to make sure everything has emerged. We just can’t take the thought of continuing to find fleas on us and carrying them into our bed after our newborn arrives. Thoughts?