Also unfortunate -- your contractor's sealing efforts may have made the problem even worse, since it essentially eliminates dry-out for a slab...  

I still might pay a few thousand to seal up our loft into an additional bedroom.  

If so you might need to remove hardwood and baseboard, and paint subfloor will Kilz paint to seal in odor, then put down new wood floor.

Personal friend is a plumber and he uses a system of pressurizing the system and injecting liquid plastic to seal it all up - - 20 year warranttee.Here in our locale, slabs frequently crack due to soil expansion and when fixing one of these, we jack-hammer the interior and r/r all the plumbing at one time.

Sealing it will have to be done almost yearly he states.

They also suggested sealing the paint with something like Kilz.

The roof was replaced by the previous owner but, I don't believe the flashing for the skylight was replaced/sealed properly.

The roof was replaced by the previous owner but, I don't believe the flashing for the skylight was replaced/sealed properly.

So we can seal some wholesaling deals, and preferably agents that know the game of wholesaling.

Few salesmen will tell you this, but NEVER use a window cleaner containing ammonia - - it will destroy the seal on the frame-glass contact and let moisture between the panes which ruins the whole purpose of dual pane glass.