I finally broke a plastic lawn chair the other night. For what it's worth, the chair was old, and it wasn't quite my weight that broke it, I'm only 170. It was feeling sorta flimsy though, and if I sat back in the chair it started tilting back a bit. I forgot for a moment and leaned back to recline a little, and the chair started tilting back. I leaned forward quickly, but all that did was flip the chair back faster, so the chair flips and I land on top of it smashing it.
I don't think my weight really had so much to do with it because I didn't smash it just from sitting in it, but I suppose it might not have occurred to a smaller person, either.
6 months