Why would you build anything (apart from a garden shed) that had a life-span of 50 years?
My pub that I sold 5 years ago was at least 450 years old..
Also sold a house in Yorkshire at the same time which is now 105 years old...all perfectly good buildings...
Still trying to find the age of my current property.... but has to be over 80...and with care, and some work, will last a helluva lot longer!