myredracer wrote:
Some sub-floors are OSB and some are plywood. I would expect more potential trouble with OSB. Our TT has plywood which is one of the reasons we bought it. I wouldn't buy one with OSB.
I'm not really sure what exactly defines "ultra-lite". I think it's more of a marketing ploy to suck people into thinking their TV can handle the weight.
It's not always about a single material subfloor. Some mfgs. use a composite structure of luan or cheap plywood and foam. Although this type of sandwich construction has a lot of strength along it's shear face axis, it is hard to get real strength through the composite core axis. I would venture that the "spongy floor" complaints happen in high traffic areas, around the entry or in front of the sink cabinet.
FWIW, if your S&B house or apartment was built in the last 20 years, you'll probably find OSB is under your feet. OSB is rated at higher load and water resistance than interior plywood. Mostly true for roof sheathing, as well but depends on geography for that.
