---
url: https://qsteelcad.com/en/turkey-light-steel-regulation-2027/differences-from-tbdy-2018
language: en
alternate: https://qsteelcad.com/hafif-celik-yonetmeligi/tbdy-2018-farklari
updated: 2026-11-06
publisher: RENMAE Teknoloji ve Yazılım LTD. ŞTİ.
---

# TBDY 2018 and the 2027 regulation compared

The main differences between the two texts, topic by topic, side by side with article numbers.

| Topic | TBDY 2018 Chapter 10 | 2027 regulation annex | Article |
| --- | --- | --- | --- |
| Design method | ASD (GKT) or LRFD (YDKT) | LRFD (YDKT) | Section 4.2 |
| Minimum yield stress | 235 MPa | 250 MPa; 220 MPa allowed for purlins, façade girts and non-load-bearing studs | Section 2 |
| Wall thickness range | 0.45 to 16 mm | 0.45 to 4 mm | Section 2 |
| DX51D to DX57D | No separate ban | Not used in load-bearing studs | Section 2 |
| Load-bearing stud wall thickness | At least 0.8 mm | At least 0.9 mm | Section 6 |
| Steel-sheet sheathed panel | 10.2.1.1 mentions OSB and plywood | Among High Ductility Level systems | Section 3 |
| Buildings above 10.5 m | No separate ratio | Demand/capacity in studs at most 0.90 | Section 6 |
| Bracing layout | Figure 10.2 example layouts | One continuous member between top and bottom track | Section 6 |
| Circular hole / web | < 0.70 | < 0.40 | Section 10.1 |
| Between holes, centre to centre | At most 600 mm | At least 600 mm | Section 10.1 |
| Galvanizing | Reference to a standard | At least 180 or 275 g/m² according to Annex 1 | Annex 1 |
| Wind lower limit | Not in the text | Basic speed 28 m/s, characteristic load not less than 0.5 kN/m² | Section 4.3 |
| Floor vibration | None | At least 8 Hz, span/depth at most 18 | Section 7.5 |
| If floor openings exceed 3% | Not in the text | Shell element model and load transfer mechanism | Section 7 |
| Temporary stability | No separate heading | Erection sequence and temporary bracing rule | Section 10.2 |
| Checklist | None | Table 10.1, eight headings | Section 10.3 |
| Fire design | None | Shown by test or by calculation | Section 11 |
| Modular and hybrid | None | 14 m limit, 10% rule | Section 12 |

The table is our own comparison of the two texts and shows the main differences. An article that is not listed here has not necessarily stayed the same.

> This page is an independent guide prepared by RENMAE. It is not the official text and does not replace legal or engineering advice. The binding text is the one published in the Official Gazette.