Horrible Floor Joisting
I sure wish I would have taken a picture of what I discovered. I may at some point go back in there to take a picture of what I had to repair.
My floor was soft in a 2013 Sierra 31FK which has NEVER had a leak and is in immaculate condition, nothing has every been spilled on the floor. After cutting my belly pan and removing the insulation barrier, it was obvious that the manufacture had done a few things wrong.
1. Cut vent hole in area which the tongue and grove existed without using any support.
2. The wood floor joist was not connected all the way across and served zero purpose..
Due to the bad floor joist location and construction the tongue and groove broke over a period of time making the floor even more spongy in that area of the floor.
I was able to fix this issue by attaching a metal bracket to the metal crossbar members, thus giving the unconnected wooden joist something to lay on.
I also placed a 1 inch by 1.5 inch strip of wood under the floor seam (tongue and groove) and screwed along both sides of the seams. BE VERY CAREFUL doing this, so not to go up through your floor. I measured the thickness of both the flooring and the 1inch strip and was careful not to sink the screw very far into the support strip.
This has resolved my issue and allowed my OCD to focus on something else for a while.
I will also ad that I was rather happy to see the type of wood used on the Sierra 31FK in comparison to the floor type I had in my old 2009 Flagstaff. Real wood vs Cardboard/foam.
A picture would say a thousand words and I don't want to go back in there to take it. Depending on the interest in my response, I may do so anyways.
Love and Light!