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0. Technical guide to composite slabs: design, calculation, components and installation

This Technical Guide to composite slabs constitutes a structured manual for the design, calculation and execution of steel–concrete composite slabs with profiled decking. Its content is developed in accordance with Eurocodes 3 and 4, UNE-EN 1994-1-2 for fire resistance, and the current Structural Code.

A composite slab is a mixed system in which the profiled steel sheet acts as a permanent formwork during the concreting phase and as an active part of the structural section in service. Proper design requires simultaneous consideration of:

  • Behaviour during the formwork stage
  • Behaviour during the composite stage
  • Ultimate and serviceability limit states
  • Fire resistance requirements
  • Real construction conditions

This guide organises these criteria into thematic sections for a structured and coherent understanding of the system.

Structure of the composite slab technical guide

1. General system concepts

This section introduces the definition of the composite system, its application scope, and the distinction between the element (sheet/profile) and the structural system (composite slab).

  • Composite deck: definition, behaviour and applications
  • Composite slab: structural characteristics and applications
  • Structural and construction advantages

2. Structural design of composite slabs

Design must consider both working phases and identify the governing variable: span, load or fire resistance.

  • System phases: formwork and composite stage
  • Structural design criteria
  • Calculation using resistance tables and design report
  • Support spacing
  • Profile selection
  • Applicable standards (Eurocodes 3 and 4)

3. Fire resistance of composite slabs

Fire resistance is verified according to UNE-EN 1994-1-2 and depends mainly on:

  • Total slab depth
  • Effective reinforcement cover
  • Bottom reinforcement area
  • Profile geometry

4. Components of the composite slab

Performance depends on proper component selection:

  • Profile types
  • Thickness
  • Base material
  • Concrete types
  • Reinforcement
  • Shear connectors

5. Construction and detailing

Execution phase considerations:

  • Installation
  • Fixings
  • Minimum supports
  • Deflection control
  • Unpropped slabs
  • Integration in steel structures
  • Cantilevers and openings

6. Alternative system: permanent formwork

Use of profiled sheeting without structural collaboration.

Guide methodology

  • Sequential reading
  • By project phase
  • By governing variable

Conclusion

Composite slabs are a well-established structural system whose effectiveness depends on the proper integration of design, standards, and execution. Identifying the governing design variable, selecting the appropriate profile, and verifying both working phases are the key pillars of a rational design approach. This Technical Guide structures these criteria into a coherent digital manual, enabling an organised and technically sound consultation. The content is based on technical experience gained from real projects and on the preparation of design reports in accordance with Eurocodes.

Technical manual for composite slabs

For a complete definition of the system, design criteria, calculation basis, resistance tables, construction details, and installation procedures, please refer to the Incoperfil Composite Slab Technical Manual, available upon registration in the Documentation section of the website.

Last update: February 2026

© Incoperfil. All rights reserved.
The technical content of this article forms part of the Composite Slab Technical Manual and the documentation registered by Incoperfil with ColorIURIS (Record No. 1-INCOPERFIL-12.2025).

Home / 0. Technical guide to composite slabs: design, calculation, components and installation

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0. Technical guide to composite slabs: design, calculation, components and installation

This Technical Guide to composite slabs constitutes a structured manual for the design, calculation and execution of steel–concrete composite slabs with profiled decking. Its content is developed in accordance with Eurocodes 3 and 4, UNE-EN 1994-1-2 for fire resistance, and the current Structural Code.

A composite slab is a mixed system in which the profiled steel sheet acts as a permanent formwork during the concreting phase and as an active part of the structural section in service. Proper design requires simultaneous consideration of:

  • Behaviour during the formwork stage
  • Behaviour during the composite stage
  • Ultimate and serviceability limit states
  • Fire resistance requirements
  • Real construction conditions

This guide organises these criteria into thematic sections for a structured and coherent understanding of the system.

Structure of the composite slab technical guide

1. General system concepts

This section introduces the definition of the composite system, its application scope, and the distinction between the element (sheet/profile) and the structural system (composite slab).

  • Composite deck: definition, behaviour and applications
  • Composite slab: structural characteristics and applications
  • Structural and construction advantages

2. Structural design of composite slabs

Design must consider both working phases and identify the governing variable: span, load or fire resistance.

  • System phases: formwork and composite stage
  • Structural design criteria
  • Calculation using resistance tables and design report
  • Support spacing
  • Profile selection
  • Applicable standards (Eurocodes 3 and 4)

3. Fire resistance of composite slabs

Fire resistance is verified according to UNE-EN 1994-1-2 and depends mainly on:

  • Total slab depth
  • Effective reinforcement cover
  • Bottom reinforcement area
  • Profile geometry

4. Components of the composite slab

Performance depends on proper component selection:

  • Profile types
  • Thickness
  • Base material
  • Concrete types
  • Reinforcement
  • Shear connectors

5. Construction and detailing

Execution phase considerations:

  • Installation
  • Fixings
  • Minimum supports
  • Deflection control
  • Unpropped slabs
  • Integration in steel structures
  • Cantilevers and openings

6. Alternative system: permanent formwork

Use of profiled sheeting without structural collaboration.

Guide methodology

  • Sequential reading
  • By project phase
  • By governing variable

Conclusion

Composite slabs are a well-established structural system whose effectiveness depends on the proper integration of design, standards, and execution. Identifying the governing design variable, selecting the appropriate profile, and verifying both working phases are the key pillars of a rational design approach. This Technical Guide structures these criteria into a coherent digital manual, enabling an organised and technically sound consultation. The content is based on technical experience gained from real projects and on the preparation of design reports in accordance with Eurocodes.

Technical manual for composite slabs

For a complete definition of the system, design criteria, calculation basis, resistance tables, construction details, and installation procedures, please refer to the Incoperfil Composite Slab Technical Manual, available upon registration in the Documentation section of the website.

Last update: February 2026

© Incoperfil. All rights reserved.
The technical content of this article forms part of the Composite Slab Technical Manual and the documentation registered by Incoperfil with ColorIURIS (Record No. 1-INCOPERFIL-12.2025).