We read the remotes and the underside meters every 3-4 months and check them against each other.

You could add mineral wool or batt insul to the underside of the floor to catch the should.  

You can use blown insulation or you can get a 2 lbs. closed cell polyurethane froth pack from Foam it Green spray foam insulation and spray the underside of the roof.

Hellomy Brrrr house spends high utility bills($400 per month in Easten canada) and I'm thinking putting 2 inch foam insulation under siding when i install new siding.

Most dramatic, as a plumber was working in the basement correcting the furnace vent, the brick underside of the fireplace hearth came crashing down.

Fire-resistance-rated wall assemblies shall extend to and be tight against the exterior walls; and shall extend from the foundation, through the attic space and to the underside of the roof deck.

I would also consider closed cell foam insulation on the joists and underside of the subfloor.

I'm not sure what their capabilities are, but if they can bore some blind-holes on either side of the crack, they can probably tie both sides of the table together with clamping hardware (all on the underside of the table).

But, I don't like to seal the underside of decking.Don

Environmental moisture vapor, within the air or being released from the ground, can easily collect on the underside of flooring.