Looking back at most structures, about 70% of well-maintained structures will last for between 100–120 years with modern methods. For every 10 years beyond that you’ll lose about 10% of the remaining.
For average maintained structures only about 50% make it to 100 years with the same 10% loss each additional 10 years.
Poorly maintained structures become shacks in 30 years or less.
Abandoned structures become shacks from 6 months to 5 years depending on the climate.
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