Ironman 3 really hurt the image of Tony's suit durability. Didn't it get disassembled by a truck and him pushing it over at one point?
That's specific to the way the Mark 42 is designed, though. It joins together in pieces and parts and it's also supposed to be the one Tony designed after like two straight days without sleep, so it's not his most durable at all. Doesn't seem like he came up with anything to fuse the pieces together once it's assembled.
But presumably whatever new suits he designs after fully recovering from his nervous breakdown will be of higher quality.