As construction costs, and people’s expectations, increase there is a requirement for buildings to be erected quickly and to be as sustainable and cost efficient as possible.
Steel frame construction is not a new concept and now accounts for over 70% of non-domestic construction in the UK. Buildings such as schools, hospitals, shopping centres and distribution warehouses are often constructed using steel frame.
Whilst the cost of steel frame construction is project specific and heavily influenced by the build programme, site access, required internal building spans and the overall design; steel boasts the highest strength to weight ratio of any construction material and is capable of creating a stronger building with far less material than one built of concrete. And, fewer materials equates to reduced material costs and an overall cheaper build.
Another element which can also be beneficial to budgets is the specification of composite concrete floor systems alongside steel frame.
Composite concrete floor systems comprise of profiled steel decking onto which is cast an in situ concrete floor slab reinforced with either steel mesh or steel fibres. Together, the composite concrete floor slab provides greater load bearing capabilities and improved fire performance than either material used in isolation.
Steel decking, or metal deck as it is also known, is a sheet of steel with a gauge of between 0.9mm and 1.5mm. The steel deck is shaped during manufacture into different profiles ranging from 50mm to 206mm deep.
Shallow profile steel decks are generally referred to as dovetail or re-entrant and are most commonly specified for short spans. Deeper decks are called trapezoidal and are used to achieve longer spans.
The depth of the profile influences factors such as load capacity, unpropped span capability and the thickness of an in situ concrete floor slab. The combination of deck and concrete slab thickness can also influence the composite concrete floor system’s fire rating.
Kingspan is a leading manufacturer of profile steel decking and produces 9,000 tonnes of steel deck each year. Marketed as ‘Multideck’, the high-performance steel decking is available in five different profiles and offers span widths of up to 6 metres.
Let’s take a look at each multideck steel decking profile in detail:
Kingspan Multideck MD50 is a 50mm dovetail rib profile steel deck capable of maximising the bond between deck and concrete due to its shape and to shear keys on the flange and webs of the ribs. This enables the profile to achieve a best in class load capability.
The deck can deliver spans of up to 4 metres unpropped and is available in a gauge range up to 1.2mm.
The minimum concrete slab depth achievable when using Multideck MD50 is 100mm, and this combination offers a fire performance of 1 hour. Other combinations can offer fire performance of up to 4 hours.
The original and most frequently specified steel deck on the market for composite beam design is Kingspan Multideck MD60.
MD60 is a 60mm trapezoidal profile that provides an excellent composite union between the steel deck and concrete. This delivers spanning of up to 4.5m unpropped.
The profile has a gauge range of 0.9mm to 1.2mm. MD60 also has the most efficient concrete section of all of the Multideck profiles requiring up to 20% less concrete.
With a 130mm concrete slab depth, MD60 can deliver 1-hour fire performance. Up to 4 hours fire performance is achievable with other slab depth combinations.
Multideck MD80 is an 80mm deep trapezoidal profile that can deliver longer 5.4m unpropped spans.
The profile is available with a gauge of between 1mm and 1.2mm delivering economic composite slab solutions.
Fire performance of 1 hour is possible with a 140mm slab depth, however up to 4 hours can be achieved depending on the deck/concrete ratio.
Multideck MD146 is the longest spanning deck on the market capable of achieving spans of up to 6m unpropped.
Just as with MD60 and MD80, Multideck MD146 can be installed on the top flange of the structural steel frame and does not require ASB beams to provide support.
MD146 is therefore a direct alternative to precast concrete slabs, with the added benefits of faster installation times and, potentially, more cost-efficient builds.
MD146 also requires up to 31% less concrete than MD80, this equates to a saving in weight of the overall structure which leads to cost efficiencies in the building’s overall steel structure and its foundations.
The 146mm profile is available in gauges of 1.2 and 1.5mm. With this profile, it’s possible to achieve a shallow floor construction of just 215mm.
Multideck MD206 was designed for use in the construction of raised deck or multi-storey car parks.
It’s an exceptionally long spanning steel deck which can achieve clear beam distances of up to 5.6m unpropped.
It has a deep 206mm profile and is exceptionally lightweight allowing it to be installed without a crane.
One of the major benefits of Multideck MD206 is that is can be colour coated on the underside with a stove enamel lacquer. This provides the benefits of additional corrosion protection but also can be used for car park level indication.
All of the Kingspan Multideck profiles can be manufactured as XP; a metallic coating which provides the steel deck with up to three times more corrosion protection in outdoor environments than standard galvanising alone.
The metallic coating is Magnelis® and comprises of zinc and 3.5% aluminium and 3% magnesium. The unique chemical composition also provides a ‘self-healing’ effect for damage and cut ends.
Steel and Sustainability
Steel is one of the most recycled and recyclable materials on the planet. Around 40% of all ‘new’ steel is recycled scrap. In the UK, up to 94% of steel is recycled when a building is demolished.
Kingspan is taking its sustainability commitments a step further through an investment in H2 Green Steel, a company pioneering new green production methods for steel manufacturing using hydrogen.
Kingspan has invested in the first round of equity fundraising and has pledged to by the majority of its steel from H2GS by 2024, when the first production line will go live.
The production of H2 Green Steel emits 95% less CO2 than traditional manufacturing methods.
About Metal Deck Steel Deck Contractors
For more information or to discuss an upcoming project please call the technical team on 01695 555070 or send a contact form.