Soft spot in floor

[Rjpetr65]

I have an 04 Sunseeker that has a soft spot about the size of a grapefruit near the bathroom in the living area. No leaks that I can see from anywhere. Perhaps the previous owner had some sort of leak.

Any suggestions for an easy and long term fix? Although I suppose that “easy and long term” is sort of an oxymoron like jumbo shrimp!

I really don’t want to start cutting out pierces of flooring if it’s not necessary.

Thanks
Rich

[Surveyor Mike]

If there's no apparent leak I guess it's coming from the bottom. You could probably put some Automotive grade flat sheet metal spanning the hole for rigidity underneath the linoleum or carpet glued to the subfloor. Same on the bottom side once you remove the black tar paper like barrier to see better. Good luck