Products & Services

Slim Floor

CoSFB – Composite Slim-Floor Beam

The CoSFB (= Composite Slim-Floor Beam), a new development from ArcelorMittal, combines the advantages of composite design with traditional slim-floor construction. The connection between in-situ concrete and the hot rolled steel section is assured by concrete dowels. These dowels are openings in the web of the steel section, penetrated by reinforced concrete. Thanks to this innovative shear connection the composite action is assured without an increase of the construction height! Due to the composite action the stiffness and robustness of the structure is significantly be increased. In addition CoSFB fulfills the requirements for fire resistance classes R60 and R90 (R120) without any passive fire protection. CoSFB is an economic solution for sustainable construction.

Typical application range of CoSFB is beam span from 8m up to 14m, with a construction height of only 40cm and a beam distance up to 10m. CoSFB fits perfectly to the demands of modern architecture to long spans.

German Technical Approval



Design aid brochure of bauforumstahl
ArcelorMittal Europe–Long Products is awarded by the German Steel Construction Industry for the development of “CoSFB”, an innovative concrete dowel technology
CoSFB animation with Cofraplus 220 (mp4)

SlimFloor Construction

Developed and offered by the ArcelorMittal group, the “Slim Floor” system is a fast, innovative and economical solution which marries cellular concrete slabs with built-in steel beams.

The secret of the design is a special kind of girder with a lower flange which is wider than the upper flange. This arrangement makes it possible place the floor slabs directly onto the lower flange of the beam, the beam is integrated into the slab.

Created to eliminate beam downstands at the level of the floor slabs, this reliable and economic prefabricated component unit gives the architect new scope for imagination and guaranteed economy for working spans of up to 14 metres.
The reduced height of the slabs and the advantage of a considerable degree of fire resistance make for maximum freedom in creativity.

The “Slim Floor” construction optimizes the effective volume of the building and offers a number of advantages.

Floor thickness reduction:

This concept leads to a total floor thickness between 20 cm and 40 cm. The clear height can be increased, extra floors can be added or the total height of the building can be

reduced. This degree of flexibility allows great freedom in the design of the façade and the roof and savings can be made.

Incorporating under-floor technical equipment:

The integration of the beams makes it easier to build in under-floor technical equipment (air-conditioning, piping, electrical and IT networks…) and simplify the fitting of false ceilings.

Freedom in ground floor design:

The structural characteristics of the components – up to 8m beam span of non- composite beams and up to 14m beam span for composite beams and 14m span for the slab – open work spaces can be created. Due to the absence of intermediate columns, the area can easily be re-organized and adapted to future esthetic and functional needs.

Built-in fire resistance:

The integration of the upper flange and the web of the beams in the slab provide structural protection which meets most regulatory requirements, no additional fire protection is needed.

Light structures:

The steel structure is composed of elements which are all always lighter than structural elements made of concrete. ArcelorMittal offers a wide range of innovative light slab solutions, e.g. Cofradal® and Cofraplus®220.

Easy to build:

The fast and simple assembly of the prefabricated components is almost entirely unaffected by atmospheric conditions. This makes it easier to meet site deadlines and to reduce construction costs.

Competitive pricing:

The weight of the steel beam per square meter is generally from 15 to 25kg/m2. This low material consumption leads to very competitive prices throughout the whole span range covered by the system.

Sustainable construction:

The steel structure is 100% recyclable and reduces the number of transports to the job site and the building site disturbances.

There are three types of Slim- Floor Beams:

A plate is welded under a hot rolled section. The SFB manufacturing costs are lower than for an IFB, but the height heff is the height of the chosen hot rolled section and can not be adjusted. This solution is perfectly appropriate for small scale standard projects where materials are immediately available.
IFB Type A
A lower plate is welded onto a section cut at the web. The distance bp has to be determined in accordance with the specific requirements of the slab elements.
IFB Type B
As for type A, a plate is welded onto a section cut at the web. But for type B the plate is replacing now the upper flange Type B beams are suitable for small spans.
Slim Floor Brochure is available in our library