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An Illustration of Composite Metal Decking Shown as Part of a Composite Floor Slab

What is Composite Metal Deck?

In this short knowledge article, we’ll answer the question “What is Composite Metal Deck?” and what are some of the advantages of specifying it for use in construction. We’ll also look at concrete floor design and construction and the fire performance of composite metal flooring.

Composite metal deck is a sheet of thin profiled steel used in the formation of reinforced concrete floors in steel frame construction.

Composite metal deck can have shallow or deep profiles depending on the end requirement. The length, and potential span, of the metal deck is dependent on factors such as gauge and load requirement. Visit our metal decking products page for more information.

The composite metal flooring is laid and fixed between the horizontal beams of a steel frame building. A concrete floor slab, reinforced with steel mesh sheets or steel fibres, is cast on the composite metal decking to create a composite concrete floor slab.

An Illustration of Composite Metal Decking Shown as Part of a Composite Floor Slab
Composite concrete metal decking within a composite floor slab

The composite action is extended to the supporting steel framework through the application of shear studs which are stud welded through the steel decking on to the top flange of the steel beam before the concrete is cast.

A specialist stud welder from raised floor solutions at work on a steel decking contract
Shear studs being welded on composite metal deck by a stud welder

The composite floor slab is reinforced with steel mesh sheets, or rebar, which control cracking, resist longitudinal shear and improve the composite concrete floor slab’s tensile strength in the event of fire.

newly laid composite steel decking with mesh sheets in place ready for casting of concrete
Sheets of composite metal deck on which is laid steel mesh reinforcement

Composite metal deck, and the subsequent composite concrete floor slab, is used as formwork in construction, particularly on multi-storey or high-rise buildings such as residential apartments, office blocks and multi-storey car parks.

The core advantages of specifying composite metal deck for construction is the resulting strength, load bearing ability and fire performance of the finished concrete floor slab, which is greater than that of either steel or concrete in isolation.

Other advantages of specifying composite metal deck for floor construction include:

  • Composite construction is a lightweight method of formwork therefore the overall steel work weight is reduced
  • Foundation requirements, and therefore costs, are reduced
  • Less concrete is used, therefore less weight and less waste
  • Reduced number of props (columns) required due to long spans achieved
  • Overall project times are reduced due to increased speed of construction
  • Greater flexibility for designers due to column free layouts and compatibility with complex designs
  • Minimal stockpiling storage requirements on site
  • Provides a safe working platform and overhead cover for follow-on trades
  • Exposed composite metal deck ceilings can be utilised to fix services
  • The resulting reinforced composite floor slab can offer up to 4 hours fire performance

Fire Performance and Composite Metal Deck

Whilst composite metal flooring will help slow the spread of flames and smoke in the event of a fire, it is not regarded as a fire barrier in isolation.

When quoted, fire performance ratings are based on the complete composite concrete floor slab and take into consideration the following:

  • the metal deck profile specified
  • span width
  • frequency of propping
  • concrete thickness
  • type of reinforcement used, e.g. mesh or steel fibre

However, a key advantage of composite metal deck in fire performance is that it will help reduce the speed at which the temperature of the concrete floor slab increases whilst controlling cracking and flaking. Therefore, in the event of a fire, the structural integrity of the composite concrete floor slab, and the building, is maintained for longer.

Composite Concrete Floor Slab Design

Metaldeck and Metcon, the steel deck and composite floor construction divisions within Raised Floor Solutions, offer an expert reinforced concrete floor slab design service using state-of-the-art Kingspan software.

Kingspan is a leading global manufacturer of composite metal decking with five different steel deck profiles available offering span widths of between 4m and 6m and contributing to a composite concrete slab fire performance rating of up to 4 hours.

The expert in house design team at Raised Floor Solutions will design a composite concrete floor slab in line with Eurocode, or whichever code has been used to design the structural steel frame work, and will provide guidance on the correct steel deck flooring to specify for a project based on the following:

  • Fire performance rating to be achieved
  • Concrete slab thickness
  • Required load requirements (static and dynamic, line and point)
  • Desired Unpropped Span Widths

For details on the span widths, concrete thickness and fire performance of Kingspan’s range of Multideck profiles view our steel deck products page where you can also download data sheets. For more information on metal deck and how it is used in composite concrete floor construction visit our knowledge article.

For a no obligation and confidential discussion regarding the suitability of composite metal decking and composite concrete floors for your construction project contact the Metaldeck and Metcon teams on 01695 555070 or email us.

To learn more about steel floor deck and composite concrete floors read our in-depth knowledge article.