Somewhat off-topic anecdote on this: my father in law designed a very rough draft of "blueprints" for his parents new house in rural China (Xinjiang) using MS Paint, local labourers built it in a few months and it's still standing 10 years later!
I would expect a house to last 100 years. A family member once bought a house that is over 400 years old (and still standing).
Then again, construction and houses are way more expensive in Europe/Germany. They're planning to tear down and rebuild my old high school from scratch, current estimate: 85 million euros total.
http://www.monomoy.edu/page.cfm?p=931
(A regional high school school for about 700 students, 168,000 square feet)