Well after getting the metallic pop sounds from stopping in the master bedroom by silver duct tapping the seams of the floor heat register we are now getting very annoying (and cheap sounding!) creaking of the alum. floor structure.
I started digging in and noticed the floor doesn't make full contact with the joists in all spots. Also, the builder seemed to have gotten most of the floor decking adhesive EVERYWHERE except on the joist to quiet the floor.
I pulled up the carpet in the bedroom and found they shot a total of 6 ring nails to hold the decking - 3 of which missed.... So I found #8 self tapping taper head screws and inserted 20 of them in the 6'x4' section (mine all hit, it's called a chaulk line). This seemed to help but it was still there in a 2'x2' section.
I inspected underneath and found that the angle brackets used to make the joist framework were assembled with a small #6 self tapping metal screw. After checking with my socket set everyone of them nearly 1/3 are stripped and 1/2 were hand right.
Right now I have pulled all the bad ones and replaces with #10 self tapping metal screws and they seem to be helping. Also, I have added (2) extra fastener's at each bracket.
I have a nasty feeling the remainder of the coach I can't see was built with the same lack of atttention and cheap (and small) fastener's. I sure hope the same percentage aren't stripped and/or loose as they were in the bedroom/pass-thru area or this thing is gonna shake loose......