2007 Gulfsfream Conquest Floor problem

I'd think this varies by manufacturer, but...

Our Jayco Class C has a frame of rectangular (about 1"x2") steel, welded in a grid pattern. So in Michael's picture above, there would be lengthwise pieces spanning those crosswise beams. Styrofoam insulation inside the rectangles formed by the steel. OSB used as flooring on top, and a sheet metal skin across the bottom. Look up from the bottom and you see galvanized sheet metal. Then inside, the vinyl floor covering is on top of the OSB. I don't think the OSB is much thicker than 7/16" or maybe 1/2".

Stud Finder is an interesting thought. If I thought I could cut the floor and put an access hatch over the in-tank fuel pump, I just might. But I would not want to cut the floor and find I was right over steel framing, or worse, here a lengthwise and crosswise frame joined.

Moved to Tech Issues forum from DIY.

I don't know about your MH, but we had a spongy spot on the floor of our 2006 HTT. It had an aluminum frame with not quite 16" centers, I think it was more like 14". On HTTs, the floors are designed as one piece and compression fit together for rigidity. Not sure if that is the same with Class C MHs or not. Under the vinyl flooring was a thin layer of luan glued to the Styrofoam that is snuggly fit between the framing and then another layer of luan under it.

When I repaired our floor, I pulled back all the vinyl as far as I could and peeled up all the totally rotted wood. Then pulled up the Styrofoam. The luan under it seemed mostly dry. It appeared it was wet at one time, but it wasn't rotted, so I left it. I put new Styrofoam between the framing and then put 1/8' oak plywood on top of that.

Below are photos of the damaged area and the start of the repair.

-Michael

Took a stud finder to the floor to mark it out before I start cutting. I'll post lots of pics for the next guy that had to do this, didn't find many on here.

Also, it feels like the joists are 36" apart, surely not.