Soft floor in dove tail loading ramp in 21G

[Sureshot]

My loading ramp (dove tail, not door) has gotten soft where I load a golf cart. Spot is approx 12-15" wide on both sides where tires run. It is covered with a thin rubber, but I can not tell what the "support" is made of. Curious if anyone has experienced this and might know what "holds" everything up. Is it a safety concern driving where it is obviously sagging?? Is it safe to load or is it going to fall through!!

 

[Hoopy Frood]

Mine failed in our previous toyhauler. The water had leaked in from the air vent in the wall. It wasn't sealed well enough and over a period of 6-7 years had wicked enough water down to ruin about half the floor, and all of the wall down from the vent. Not a Grand Design.

Repaired it all with plywood. Still solid when we sold it a few years later. But the ramp door was getting spongy.

 

[Sureshot]

Thanks Hoopy. I haven't taken everything loose from the bottom yet. Curious as to what material was used for support under the rubber mat.
I thought it might be plywood, but how it's sagging I think not. Maybe some kind of composite? My bifold glass door has also come out of the top pivot pin because the base cup it sits in has also sunken in. Needs to be shimmed up to raise it back in place.

 

[Hoopy Frood]

Yeah, mine was definitely not plywood, that's what I replaced it with, but it was some kind of luan, OSB, or particle board. When it got wet, it just came apart. Lighter than plywood, but doesn't stand up to water at all. FWIW, the same thing happened to the bedroom slide floor. Water wicked down from inadequately sealed seams and it just disintegrated.