repair of soft floor in motorhome

[E_Johnsen]

Need to repair soft floor in an older Bounder. How thick does the plywood need to be? Can I cut out the old floor or should I attach the new wood to the original floor? Have heard that I may need to add more floor joists. Any other suggestions would be appreciated?
Thanks

[Boband4]

You have to cut out the damaged wood, plus a little more. You cut back to where there is support, or you have to add a support. It can be difficult figuring out how to attach the additional support. My flooring was 5/8" OSB.

[E_Johnsen]

I have purchased the motorhome recently. The reason for the damage was that they did not have covers over the fan vents. That will solve any more water damage.

[gbopp]

Did you fix the leak that caused the soft floor?
How large of an area needs replaced?
Don't put the new wood over the old floor. Remove the damaged wood.

[Dakota98]

That sounds to me like putting a band-aid on a major wound.