The integrated flaw beams (THQ) specialist

Steel construction framework illustrating load-bearing structural design.

Form meets function

What are integrated flaw beams?

Integrated flaw beams (THQ) are steel beams with a wide, hat-shaped profile that sets them apart from traditional I- or H-beams. This unique geometry provides increased strength and stiffness, making THQ beams ideal for carrying heavy loads across long spans. They are commonly used in bridges, industrial halls, roof structures, and other heavy-duty applications where high load capacity is essential. Their efficient design also makes them well-suited for demanding sectors such as petrochemicals, shipbuilding, and transport infrastructure.

The benefits of this floor system compared to traditional solutions

In recent years, integrated steel beams have become increasingly common, especially in multi-storey construction. By integrating the beams into the floor structure, a nearly flat floor surface is achieved, enhancing both structural efficiency and usable space.

Compact construction height

The distinctive shape of the integrated flaw beam allows for a low floor build-up, reducing overall building height and delivering cost savings on façade and wall materials.

Space for installations

Pipes, cables, and ventilation systems can be easily placed within the floor build-up without the need for additional support structures.

Efficient material use

Thanks to its optimized profile, steel is applied exactly where it is structurally needed - reducing weight without compromising strength.

Quick installation

The prefabricated steel and concrete elements are easy to place, significantly shortening construction time and minimizing the risk of installation errors.

High fire resistance

The integration of steel and concrete offers inherent fire resistance while reducing the need for additional fire protection, lowering overall costs.

Low maintenance and design costs

The structural simplicity and standardization of THQ beams enable a predictable, cost-efficient design process.

Factory-applied fire-resistant coating (up to 120 min)

We apply fire-resistant coatings directly in our facility, allowing us to increase the standard fire resistance from 30 minutes up to 120 minutes.

Customization possible

STM Group produces integrated flaw beams fully tailored to your project - calculated, manufactured, and finished to your exact specifications.

Integrated flaw beams showing optimized steel–concrete interaction.

Close up of integrated flaw beam showing optimized steel concrete interaction.

From design to delivery

STM Group oversees every project from calculation to final delivery. Our engineers design and optimize integrated flaw beams in the Netherlands, while production takes place in our state-of-the-art facility in Slovakia. With automated processes, strict quality control, and in-house transport, we ensure precision, flexibility, and reliable delivery at every stage.

Design

Our engineers calculate and optimise hat beams entirely in-house. Using Tekla and other advanced 2D and 3D software, we model every structure in full detail, enabling faster coordination and maximum accuracy. We provide all structural calculations required for building authorities, as well as any detailed calculations needed for your project. Efficient, precise and fully aligned with the design requirements.

Design and calculation are carried out in Tekla Structures to ensure maximum accuracy and a fully coordinated 3D model.

Engineering

Based on the structural calculations, we develop the hat beams fully to workshop level. We import the digital floor supplier’s model and ensure a seamless connection between steel and concrete. All engineering is carried out in the Netherlands by experienced designers and structural engineers, ensuring smooth communication and consistent quality throughout every stage.

Our engineering is performed entirely in-house, giving us full control over accuracy, coordination and delivery reliability.

Production

The production of our hat beams takes place in our modern facility in Slovakia, where flexibility, quality and delivery reliability are central. All beams can be supplied with a 3.1.b certificate on request. STM Group produces all three hat beam types: THQ, IFB and SFB.

Our production is EN 1090-2 EXC3 certified, ensuring the highest standards of safety and structural performance.

Coating

After production, the beams are automatically blasted to SA 2½ quality using a Gietart blasting machine. They are then coated with a two-component zinc phosphate primer from Zandleven Coatings. The beams can be supplied with a 1-layer (80 μm) or 2-layer (120 μm) factory finish, applied either on the visible side or as a full coating. Standard RAL colours are RAL 7016 (Anthracite Grey) and RAL 7030 (Stone Grey), with additional colours available on request.

We offer C5-M/FP120 coating systems for maximum durability and protection in demanding environments.

Delivery

We handle the transport of our hat beams from Slovakia with our own trucks, all equipped with track-and-trace systems so customers can monitor the location and expected arrival time of their delivery at any moment. Profiles up to 18 metres can be transported without issues, transfers or delays. This allows STM Group to guarantee reliable delivery and full control over the entire logistics process.

We offer cost-effective pricing and short lead times, ensuring efficient logistics from start to finish.

The three hat beam types offered by STM Group

Depending on the structural requirements, we supply a range of hat-beam profiles and dimensions.

An integrated flaw beam with excellent interaction between the steel bottom plate and the concrete compression layer, commonly used for long spans where construction height is limited.

DOWNLOAD THQ tables

Slim floor beams (SFB) combine prefabricated steel and concrete elements to create a flat floor structure, enabling efficient site logistics and shorter construction times.

DOWNLOAD SFB tables

Integrated flat ceiling beams (IFB) are slim-profile beams with favorable installation depth and efficient material distribution, designed to carry loads both across the span and over supports.

DOWNLOAD IFB tables

For each hat beam type, you can download the technical data in Excel format. These files include all relevant section and strength properties for design, calculation, and verification.

Explanation of the table data in Excel

m⁺: cross-section class under positive bending moment (in the span).
m⁻: cross-section class under negative bending moment (above an intermediate support).
Iy: second moment of area (moment of inertia).
Wel: elastic section modulus.
Wpl: plastic section modulus.
My;u: design value of the ultimate positive bending moment about the y-axis.
- If m⁺ = 1 or 2, My;u is based on Wpl × fy (fy = 355 N/mm²).
- If m⁺ = 3, My;u is based on Wel × fy.
- Because of transverse bending effects in the bottom plate, it is recommended to apply a reduction to My;u. The reduction depends on the selected profile and is typically less than 10%.
Vz;u: design value of the ultimate shear force.

My;u and Vz;u can be used for the design of simply supported beams. For continuous beams, these values may be applied to design the cross-section in the span. For final verification calculations and the full design of continuous beams, reference is made to the publications of Bouwen met Staal.
‍
Source: Bouwen met Staal

‍

Portrait of STM Group directors representing experience and reliability in steel construction.

Reliable partner in steel

STM as a trusted producer of integrated flaw beams

With over 30 years of experience in hat beam production, we deliver precise, custom-made components from our automated facility in Slovakia. Thanks to advanced welding techniques and strict quality controls, we meet the highest certification standards - ensuring consistent, high-quality results from design through completion.

request a quote

Frequently asked questions

What is the delivery time?

The delivery time is typically 5 to 6 weeks after receiving the final drawings, depending on the project’s complexity and the type of coating. We are happy to coordinate this with you.

Up to what length can you transport?

We can transport beams up to 24 meters. Within our standard transport options, however, there is a length limit of 14.6 meters. Transport for lengths above 14.6 meters is arranged on request.

What is your standard steel grade?

Our standard steel grade is S355J2G3. Other material grades can be supplied on request, depending on your project specifications.

Do you provide coating as well?

We offer several coating options, including our standard treatment in which all steel components are fully blasted (SA 2½) and finished with a single-layer Baril coating of 60 µm. The standard colour is SB723 (Light grey), with corrosion class CC1/CC2, suitable for indoor environments and offering a durability of 5 to 15 years.

We can also apply fire-resistant coatings or arrange thermal galvanisation if required, depending on the specific needs of your project.

Get in touch

Building strong structures together

Contact our specialists for advice or a tailored calculation. You will receive a quote within 24 hours.

request a quote