@Dillon Seal, I'm confused regarding the HML's requirement.

Our contractor was fastidious about sealing off rooms and taping unused doors, but we still found several rooms full of dust.

We agreed that I needed to remove the damaged portion of the house and seal off the remainder in order to bring the property into compliance until I am ready to rebuild.    

Agent/Lender/Appraiser/buyer maybe, but not seller.So they sealed the deal and went to closing, who knows what happened after that exactly but the closing date kept moving out month after month, the deal never closed. 

We would probably be able to finance the initial purchase, but would need to have the two units we are not living in cash flowing ASAP.As far as we can see it will need LBP remediation (in Alabama you can seal it and paint over it) so probably $6k in total for both units to be rented, and an air system in place.

So the owner may end up having improper restoration work done, doesn't smoke seal necessary areas properly, then when a renovation company comes in and finishes the work, come next hot summer season, the smell of smoke comes back). - If they look like they might consider selling, you have to start looking for restoration companies that also renovate who guarantee their work so you can figure out the cost. 

The RE talk will soften her up but the the magic tricks will really seal the deal. 

FLEX-SEAL!". 

Underneath most exterior doors is a rubber seal that contacts the threshold.

However, they clearly didn't seal up the hole in the kitchen when they were done.