---
url: https://qsteelcad.com/en/blog/modular-and-hybrid-light-steel-buildings
language: en
alternate: https://qsteelcad.com/blog/moduler-hibrit-hafif-celik-yapilar
updated: 2026-11-06
publisher: RENMAE Teknoloji ve Yazılım LTD. ŞTİ.
---

# Modular and hybrid light steel buildings: the 14 metre limit and the 10% rule

The new regulation defines modular and hybrid buildings for the first time. How high can you go with modules alone, and which rule applies in a hybrid building? A summary of Section 12 is in this article.

## Short answer

Under Section 12 of the 2027 light steel regulation, systems carried by modules alone are limited to 14 metres; taller buildings need a reinforced concrete or steel rigid core. In a hybrid building, if the light steel carries more than 10% of the lateral load, it is designed under this regulation as High Ductility Level.

## Key points

- In a system carried by modules alone, building height is at most 14 metres.
- Taller buildings must have a reinforced concrete or steel rigid core.
- The module joint is checked for shear and axial force together (Equation 12.1.1).
- In a hybrid building the limit is 10%: if light steel carries more than that share of the lateral load, this regulation applies.
- The light steel track is anchored to suit the reinforced concrete core wall.

Modular and hybrid buildings are the fastest-growing uses of light steel, but in Turkey they had no definition at regulation level. Section 12 changes that. Because Article 2 of the regulation lists its scope as prefabricated, hybrid, modular and on-site profile construction, this section applies directly.

## How is a modular building defined?

Modular buildings are systems formed by assembling volumetric units prefabricated in a factory on the site, making up the whole or a certain part of the structure. The load-bearing system inside a module can consist of cold-formed members with C, Z and U sections that meet the cross-section requirements of Section 3, together with structural steel members.

## How is the module joint calculated?

Where module members are connected externally, the joint is designed according to the bolted connection provisions of Section 8.3. The shear force acting on each joint is calculated by dividing the total shear force on the storey concerned by the number of joints, taking into account the shear force caused by eccentricity. The overturning moment enters the axial force demand.

Equation 12.1.1:

```
V joint / (0.5 · Vd,joint) + P joint / (0.5 · Pd,joint) ≤ 1
```

It is verified that the joints stay within elastic limits under design loads. If the joint is made with an internal connection mechanism, the capacity is determined with a detailed finite element model. Where modelling cannot be done, the demand levels of the connection are verified by experimental methods.

## How high can you go with modules?

Section 12.1.5 sets a clear limit: in systems carried by modules alone, building height is permitted up to 14 metres at most. For taller buildings a reinforced concrete or steel rigid core is mandatory. The whole modular system is made stable against lateral loads internally or by joining module groups, and TBDY is taken into account for P-δ and P-Δ effects.

| Topic | Rule |
| --- | --- |
| Structural behaviour | Designed to behave at High Ductility Level |
| R and D values | Selected in accordance with TBDY provisions |
| Transfer between modules | Structurally continuous and safe connection systems |
| Fire | Section 11 in each module; tested gaskets and insulation at joint surfaces |
| Quality control | Carried out at factory dispatch and documented |
| Transport | Lifting points are calculated in advance and shown on the site plan |

## What is a hybrid building?

Hybrid buildings are systems in which cold-formed steel members work integrated with reinforced concrete, hot-rolled steel or timber systems, so that more than one construction technology is used structurally. If the light steel part consists of modules, the structural system is still classified as hybrid.

## How does the 10% rule work?

| Lateral load carried by the light steel | Result |
| --- | --- |
| At most 10% | The system type (BYS), R and D values are selected according to the relevant section of TBDY; design is made for the part that carries the lateral load |
| More than 10% | Light steel load-bearing systems are designed under this regulation; the system is designed as High Ductility Level |

The regulation requires the load flow to be shown in the calculations and the resulting forces to be transferred to the lateral load resisting system. The diaphragm action and the stiffness contribution of the panels are also included in the calculation.

## What to watch at the interface

- Deformation, displacement and cracking risk arising from stiffness differences are taken into account.
- Connection elements at reinforced concrete to steel and steel to steel transition zones ensure the continuity of the load transfer path.
- The capacity of shear screws, bolts, anchors, welded connections and connection plates is shown by calculation.
- If there is a reinforced concrete core, the light steel track member is anchored to suit the core wall.
- Floor or frame beams are designed to connect to this track member.
- All details are shown clearly in the architectural and structural projects.

Read next: [Lateral load path in a light steel building: from roof to foundation, step by step](https://qsteelcad.com/en/blog/lateral-load-path-roof-to-foundation)

## How is QSteelCAD used in modular production?

QSteelCAD builds the panel, the truss and the production file. It does not calculate the module joint, the core anchorage or the hybrid system. In modular production, wall and ceiling panels can be kept in the same model; the calculation of joints belongs to the project engineer.

## Frequently asked

### How many storeys can a modular light steel building have?

The regulation gives a height limit, not a storey count: in a system carried by modules alone, the building height is at most 14 metres. Taller buildings must have a rigid core.

### Is adding a light steel storey to a reinforced concrete building hybrid?

If more than one construction technology is used structurally together, the definition corresponds to a hybrid system. For an addition to an existing building, the existing structure must also be assessed; this decision belongs to the project engineer.

### Is there a quality control requirement for a module factory?

Yes. Section 12.1.7 requires production and quality control to be carried out at factory dispatch and documented.

## Related solutions

- [Create architecture from plan](https://qsteelcad.com/en/solutions/plan-to-architecture)