found soft spot in floor

Thanks for the info westend.

I already ordered 3 rolls of the tape and a new ac seal. I hope it's the 14x14 one.

To clarify. If my floor is composite, foam sandwiched between 2 sheets of plywood, is that simply sitting on top of the floor joists with the lower layer of plywood fastened to the floor joists?

I think my trailer is simply OSB with regular fiberglass insulation. One of the exterior hatches has a seal problem and water has gotten inside. When I was trying to fix it, (adding thicker foam weather stripping) I pulled back the carpeting and I could see the subfloor was simply OSB with fiberglass insulation underneath. So I assume thats how the rest of the floor is.

I also assume R13 insulation is what I should purchase to replace the existing?

A few more questions.
When I remove the sections of flooring how bad is it if I leave the sections under the refrigerator and kitchen sink if there is deterioration on those panels. Assuming I find the source of the leak and stop it?

There is a wall for the bathroom. I am not sure if I will be able to remove the plywood subfloor from under those wall sill plates. I figured I would cut around it if I need to. Is that ok?

Thanks,
iso

Different Mfgs have different ways of installing the floor. A composite panel floor is typiclly attached in a few spots to frame brackets, it is usually not installed like a typical frame-built floor, i.e. attached on 16" centers into joists. You may have a more conventional floor with wooden floor joists and OSB installed as the floor sheathing. The latter is easier to repair.

The under floor insulation will be your call as to refitting the same, installing new, or upgrading to an extruded polystyrene foam board. The price of insulation is so cheap that any of the three or combination of, will serve for you. My suggestion is that you put as much in as possible. More insulation = more comfort and less heating and cooling costs.

You can certainly cut the floor at locations that are easy to reach with conventional tools. You can always add small wood blocking or joist ledgers into the floor when reassembling your work. Fortifying those areas with wood placed into the "sandwich" will only make the floor stronger.

I cut my single 5/8" plywood floor back 6" from the exterior walls in most locations. This allowed me to install foam board pieces underneath the wall plates and under that 6" of plywood floor. When reassembling, I installed a piece of lumber underneath the cut line to support both pieces of plywood, the one remaining (6") and the larger piece removed. In one area, where there was extensive wall rot and the plywood was non-existant under the wall plate, I chipped out the bad plywood, cut nails and screws in the way with sawzall and small grinder, slid the new plywood under the wall, and reattached through a sound wall plate.

FWIW, I spent two weeks, close to 80 hrs. cutting and fitting foam board into wall and ceiling cavities. No cavity was plumb or straight so each piece was measured and custom cut, also allowing for electrical boxes and wire runs. I saw pink spots for a few days, lol. The end result of my efforts was a trailer that is like no other when seated inside. There is very little exterior noise (if windows and doors are shut) and it takes quite a bit less heat or A/C to get comfortable. Insulation in trailers rules, the more you can get into the trailer and the precision that you use if using foam board, pays big dividends going forward.

Good luck on the floor, once you dive into it, you will understand what needs to be done.