This would seal up the floor if you are going to rent it out again and allow pets.  

That was the type of man my father was, you are just there for each other, no questions.I had a big project list that started with sanding down the hardwood floors and sealing them.

If so, the ridge may very well be the culprit... either because it is sealed so tightly (not uncommon with SIPS panels) that all the vapor collects at the ridge area with no place to go.  

Make sure asbestos is encapsulated, such as sealed with paint.

What is needed to complete:-Additional painting and touchup painting of walls, trim, and blinds-Repairs to oak wood flooring, plus sanding, sealing, and clear-coating the entire floor-Laying marble tile around a fireplace-Installing a sink in a granite countertop, including cutting the holes, etc.

In general, is it best to seal grout in a rental property or not?

When the bats are out foraging at night or have migrated south for the winter, seal up the places where they can enter.

Mice cannot be a problem if they can't get in, and unless the tenants are leaving something open to invite them in, there is/must be some entry point in your house - and once mice identify an entry point, it is open season until you seal that point. 

it is worth a try to tsp, rinse, then kilz (I would use old school oil based with respirator) or shellac seal the walls..

I seldom make a move without one or more attorney's seal of approval.