Another approach advocated by Joseph Lstiburek of the Building Science Corporation, is to leave a dead air space at the top of the joist cavity with insulation filling the remainder of the cavity and a 1.5+ layer of hardboard insulation spanning the underside of the joists.

The underside of the pier and beam house had more than a foot of water in places.

It is hot on the underside and top as well.

The glass shelves - some are OK some are embedded into a plastic frame, and the plastic frame cracked on the under side.

You can buy bombs & spray.The bagged furniture can be sprayed (pull off all the cushions & get the underside, too), sealed back up & left to "cook". 

Finally, I'd plant some very nice hedges to screen the underside of the upper deck.

Or the underside of your house?

Another trick if you use rolled formica countertops is to completely varnish the undersides and edges of the sink cut-out in case any water infiltrates the sink rim etc.Pergo type products are garbage when they get wet.

If anything to fill the gaps, backing can be placed on the underside of the sheathing via the attic and then strips of existing material ie CDX, OSB, 1x6 ect. can be ripped to place and installed.What type of shingles are existing on the roof? 

Sure enough, He did not install the back splash as high as I asked him to (it was supposed to go right up to the under side of the shelves) and he somehow managed to install two different size brackets so the shelf on the right of the vent hood is shorter than the one on the left.