I've seen 1950's built "crackerjack box" houses framed with <i>good</i> red oak 2x4, on solid foundations, which would have to be burned to knock them down today.<p>I've seen 2005 era McMansion grade houses already warped and open too far to be considered repairable. They were livable for about 10 years, 14 if you could tolerate leaks. Framed with knotty fir 2x2 and structural duct tape.<p>It depends on the house. Its a lot easier to get away with building and selling absolute crap, the last two decades. There <i>have been</i> good houses built recently but the incentives all align the other way.