Earthquakes and Urban Transformation
Building Age and Earthquake Codes
The differences between the 1975, 1998, 2007 and 2018 earthquake codes, construction supervision after 1999, and what building age means for earthquake safety.
2 min read
One of the most important factors determining a building's earthquake safety is which building-code period and inspection regime it was built under. Building age alone is not a sufficient measure, but it offers a strong clue about the code period.
Code periods
| Period | Key characteristics |
|---|---|
| Before 1975 | Modern earthquake calculation limited; the riskiest part of the building stock |
| 1975 to 1997 | The 1975 earthquake code; weak implementation and supervision |
| 1998 to 2006 | The 1998 code; supervision tightened after the 1999 earthquakes |
| 2007 to 2018 | The 2007 Regulation on Buildings to Be Built in Earthquake Zones |
| After 2018 | Turkish Building Earthquake Code (TBDY 2018); performance-based design, more detailed ground conditions |
Why is 1999 a turning point?
After the 1999 Marmara earthquakes, the construction-supervision system was established and material and workmanship inspection was tightened. This is why buildings built after 2000 generally have a better supervision record on average. But a supervision record does not guarantee that any individual building is safe.
What to look at besides age
- Soil class and the soil survey report
- The layout of the load-bearing system (soft story, short column, irregularities)
- Later renovations, such as interventions that cut into columns
- Maintenance condition, corrosion and moisture
- How well the building's height and number of floors match its load-bearing system
This content is for general information only and is not a substitute for legal, financial or tax advice. Rates, amounts and legislation can change over time. Confirm current information with the relevant authority or a professional before proceeding with a transaction.