Long Span 220 Deep Decking Profile – 750mm Cover Width

RMD220 Long Span Floor Decking

RMD220 is a 220mm deep long-span floor decking system supplied by RMD Profiles in partnership with ArcelorMittal Construction. It is a fundamentally different product from the standard composite profiles in the RMD range, and it is important to understand that difference before specifying it. RMD220 uses an additive design approach: the structural resistance of the steel deck profile and the resistance of the ribbed reinforced concrete slab are calculated separately and combined to give the floor system its full resistance. Reinforcement bars within each rib are an integral and non-optional part of the structural design at every span and every fire period.

The result is a floor system capable of unpropped spans up to 5.5m and propped spans up to 8.5m, compatible with steel, concrete, and timber primary structures, and achieving fire resistance from 60 to 120 minutes without additional fire protection measures at typical slab depths. No other profile in the RMD range approaches these span capabilities from a single deck.

RMD220 is not a drop-in replacement for a standard composite profile. It requires specialist installation by qualified operatives, has lead times of 3 to 6 weeks from order, and demands careful pre-project planning of all auxiliary items before a price or programme can be confirmed. If you are on a tight programme and need deck on site quickly, RMD220 is not the profile for that job. If you have a long-span project, an unusual primary structure, or a need to eliminate secondary beams across a wide grid, it is very likely the only realistic option.

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Key Benefits

• 220mm deep ribbed profile, 750mm cover width
• Unpropped spans up to 5.5m, propped spans up to 8.5m: the longest span capability in the RMD range
• Additive design combines steel deck resistance and ribbed reinforced concrete resistance for maximum structural efficiency
• Compatible with steel, concrete, and timber primary frames: the only profile in the range suited to all three
• Fire resistance REI 60 to REI 120 achieved through rib reinforcement, without additional fire protection measures at typical slab depths
• Deep ribbed geometry produces a highly efficient structural cross-section with low concrete volume relative to slab depth
• Diaphragm action capability: when properly connected and detailed, the installed deck can provide lateral restraint to the primary structure
• Eliminates secondary beams entirely across wide structural bays, reducing steel tonnage, connections, and erection time
• 750mm cover width covers more floor area per sheet, reducing joint lines compared with 600mm profiles
• Suitable for new build, extensions, and renovation on existing structures
• CE marking with DTA No. 3.1/17-927_V1 and AbZ Z-26.1-55

Profile Specification

• Profile depth: 220mm
• Cover width: 750mm
• Available gauges: 1.13mm, 1.25mm
• Steel grade: S350 GD to EN 10346
• Corrosion protection: Galvanised ZM175, or galvanised with organic coating (Hairplus 25 micron, Category IIIa)
• Minimum concrete above deck (Hc): 80mm
• Design approach: Additive (deck resistance plus ribbed reinforced concrete resistance combined)

Sectional Properties

Section properties are for the steel profile only and do not represent the full composite resistance of the floor system. Full structural performance depends on rib reinforcement, concrete grade (C25/30), and slab depth specified by the project engineer. Source: Cofraplus RMD220 datasheet, ArcelorMittal Construction.

Panel Weight Reference

Approximate weight of a single RMD220 sheet at 3 metres length and 750mm cover width (panel area = 2.25 m²). The profile runs at 12.5 kg per metre length, which the datasheet describes as easy to handle and reducing the need for lifting devices. In practice, a 3m sheet weighs 34 to 38 kg depending on gauge. Safe manual handling procedures must be assessed by the site team before installation begins. The profile is significantly deeper and more awkward to handle than standard composite deck sheets, and mechanical lifting aids should be considered.

Concrete Volume and Slab Weight

Concrete density used in the RMD220 datasheet is 2,500 kg/m³. Slab weights below include the deck profile weight and are indicative for initial structural design. Reinforcement bar weight is not included. Ponding allowance is not included.

The deep rib geometry of RMD220 displaces a very significant volume of concrete relative to the total slab depth, resulting in a much lighter floor system than an equivalent solid reinforced concrete slab. This weight saving is one of the reasons RMD220 is viable on lightweight timber and concrete frames that could not carry a heavier solid slab.

Slab weights include deck profile at 15.14 kg/m² (1.13mm gauge). Reinforcement bar not included. Source: Cofraplus RMD220 datasheet.

Fire Performance

Fire resistance for RMD220 is achieved through the reinforcement bars within the ribs. This is different from standard composite profiles where fire resistance depends primarily on slab depth and mesh cover above the deck. For RMD220, the bar size and stirrup arrangement required for each fire period is specified by the project engineer based on span, applied load, and the required fire rating. Mesh reinforcement above the ribs is always required separately for crack control to Eurocode 2 and Eurocode 4.

Minimum Hc values only. Bar reinforcement specification, stirrups, and bar spacing are determined by the project engineer for each bay. A pre-design calculation note is available from RMD Profiles for a given set of project parameters. Source: Cofraplus RMD220 datasheet, ArcelorMittal Construction.

Diaphragm Action

One of the structural advantages of RMD220 that is frequently under-appreciated at specification stage is its diaphragm action capability. When the deck is properly installed with the correct side lap stitching, end fixings, and perimeter connections, the installed steel deck acts as a rigid diaphragm in the horizontal plane. This means the deck can transfer lateral wind loads and seismic forces from the floor level to the primary structure, providing a genuine structural contribution beyond simply supporting vertical loads.

For buildings where the primary structure is concrete or timber, diaphragm action from the deck is particularly valuable. Concrete and timber frames often lack the inherent in-plane stiffness of a steel frame with braced bays. A properly designed RMD220 diaphragm provides the horizontal stability mechanism that allows the primary structure to resist racking, transfers lateral loads to shear walls or core elements, and restrains the primary frame members laterally at each floor level.

The diaphragm design must be confirmed by the project structural engineer and is dependent on fixing pattern, connection to primary structure, and the specific lateral loads on the building. RMD Profiles can provide pre-design guidance on diaphragm action capability as part of the project-specific design service. This benefit should be considered during structural concept design, not added as an afterthought at detailed design stage.

Structural Span Performance

RMD220 achieves its exceptional span performance through the additive design approach, which leverages both the stiffness of the deep steel section and the full structural contribution of the ribbed reinforced concrete. The span tables below show indicative acceptable imposed loads (kg/m²) for unpropped construction with concrete C25/30. Bar diameter per rib ranges from 12mm to 25mm depending on span and load, with 6mm stirrups at 200mm centres in all cases. For propped construction, spans up to 8.5m are achievable.

These figures are indicative pre-design values. All RMD220 installations require a project-specific calculation from RMD Profiles or ArcelorMittal’s engineering office. Contact our technical team to initiate a pre-design enquiry.

Span performance assumes C25/30 concrete, REI 30 fire rating, deflection in service of L/350 (for spans under 3.5m) or 5mm + L/700 (for spans over 3.5m). Actual permissible loads depend on the full project specification. A project-specific calculation is always required.

Auxiliary Items: What Must Be Quantified

RMD220 requires a comprehensive set of auxiliary items that must all be identified, specified, and quantified before a complete supply price can be given. Unlike standard composite profiles where edge trim and end caps are the main accessories, RMD220 projects involve a more extensive list that can have a material impact on overall supply cost and programme.

Every project tender and pre-order checklist should address all of the following:

• Reinforcement bars per rib: Diameter (12mm to 25mm), length, quantity, and stirrup specification. Must be engineer-specified. Not supplied by RMD Profiles as standard but must be coordinated at supply stage.
• Stirrups: 6mm diameter at 200mm centres as standard; quantity and length vary with span and trough count. Propped spans require additional welded mesh at mid-supports in addition to stirrups.
• Anti-crack mesh above deck: Required to Eurocode 2 and Eurocode 4 for crack control. Grade, pitch, and coverage area must be specified and quantified.
• Edge trim: Specified to suit the total slab depth including 220mm deck plus Hc. Standard slab edge trim heights may be insufficient for a 300mm or deeper total depth. Custom heights may be required.
• Restraint straps: Required at all perimeter edge trim locations. Quantity depends on total edge trim run length and trim height.
• End caps: Required at open profile ends where sheets do not bear directly onto a closed support. Quantity depends on sheet end conditions around the floor plate.
• Side lap fixings: Self-drilling screws or equivalent. Quantity depends on sheet count and span configuration.
• End fixings to structure: Shot-fired pins or equivalent for fixing to steel or concrete support. Fixing type depends on support material. Quantity depends on support layout and fixing centres.
• Temporary propping: If propped spans are required, propping arrangement, timber packing, and adjustment must be confirmed. Propping design is not part of RMD220 supply.
• Closure plates: Required where a full sheet width cannot be achieved at bay edges. Width, gauge, and quantity depend on floor plate geometry.

Installation: What You Need to Know

RMD220 is not a profile that can be installed by a general metal deck gang without specific training and qualification in this system. The profile is 220mm deep, significantly larger and more awkward to handle and position than standard composite profiles, and the installation sequence involves more steps than a standard deck lay. Incorrect fixing, incorrect bar placement, or incorrect side lap detailing will compromise both the structural performance and the diaphragm action of the installed floor system.

RMD Profiles offers two routes to get RMD220 correctly installed on your project:

Option 1: RMD Specialist Installation. Our trained specialist teams can carry out the full RMD220 deck installation for you, including all auxiliary item supply coordination, fixing layout, rib bar placement guidance, and quality assurance. This is the safest route for contractors who have not previously installed this profile and want the installation risk managed by people who know the system.

Option 2: Guided Self-Installation. If your site team or sub-contractor wishes to install the deck themselves, RMD Profiles can provide full installation guidance, including site-specific fixing schedules, step-by-step installation instructions, and technical support throughout the installation period. This route requires that the installing operatives are briefed and supervised by your site team, and that the installation is checked at key stages.

In both cases, please contact RMD Profiles before the tender is submitted so that the correct installation route, programme allowance, and auxiliary item schedule can be confirmed for your specific project.

Why Specify RMD220?

The honest answer is: you should specify RMD220 when no other profile in the range can do the job, or when the structural and economic case for very long spans makes it the right choice even accounting for the higher installation complexity and longer lead time.

The primary structural argument is the elimination of secondary beams. On a car park or industrial distribution facility with a 9m or 10m structural grid, RMD220 spanning 5.5m unpropped or 8.5m propped between primary beams removes the need for a secondary beam row entirely. Remove a secondary beam and you remove its fabrication, delivery, erection, and two connections. On a 10,000 m² facility with a 9m x 9m grid, that is roughly 110 secondary beams that are no longer needed. The saving in structural steel tonnage, erection time, and connection work typically more than justifies the premium on the RMD220 deck itself.

The compatibility with non-steel primary structures opens up projects that standard composite profiles cannot address at all. Where the primary structure is in-situ concrete, precast concrete, or engineered timber, there is typically no mechanism for through-deck stud welding. Standard composite profiles are designed around steel beam composite action. RMD220 does not require composite beam action at the primary structure level. The deck achieves its structural performance through the rib-reinforced concrete slab working in conjunction with the steel profile. This makes RMD220 the natural choice for extensions to concrete-framed buildings, new-build projects on concrete cores, and the growing number of commercial and mixed-use projects using mass timber structural frames.

The weight advantage is a third independent reason. At 80mm above deck (Hc minimum), RMD220 produces a 300mm deep floor system weighing approximately 308 kg/m². A conventional reinforced concrete slab of similar structural depth would typically be heavier by a significant margin. On a lightweight timber frame, masonry superstructure, or refurbishment project where additional dead load on the existing structure must be minimised, that weight saving is a structural constraint driver, not a luxury.

The diaphragm action benefit rounds out the case. On a building where the primary structure has limited inherent horizontal stiffness, designing the RMD220 deck as a structural diaphragm provides horizontal stability without adding dedicated bracing elements to the frame. The deck you were installing for vertical load resistance simultaneously solves the horizontal load transfer problem. That is a genuinely efficient structural solution.

Typical Applications

• Multi-storey and single-storey car parks with wide structural grids where eliminating secondary beams across long bays is the primary structural value-engineering objective
• Industrial distribution and logistics facilities with large column grids requiring spans beyond the capability of standard composite profiles
• Service sector buildings, retail units, and supermarkets where open, column-free floor plates are a layout requirement
• New-build and extension projects on concrete or masonry primary structures where through-deck stud welding to steel beams is not part of the design
• Mass timber frame buildings where a long-span, lightweight floor system compatible with timber primary structure is required
• Renovation and floor replacement projects on existing concrete-framed buildings where new floor plates need to span long distances without introducing new intermediate steel supports
• Any project where diaphragm action from the floor deck is part of the lateral stability strategy for the primary structure

Compliance and Certification

• CE marking: DTA No. 3.1/17-927_V1 and AbZ Z-26.1-55
• Steel grade S350 GD to EN 10346
• Corrosion protection: galvanised ZM175 (ZMevolution) to EN 10346 and P 34-310, or organic coating Hairplus 25 micron Category IIIa to EN 10169+A1 and P 34-301
• Design standard: additive design approach, Eurocode 2 and Eurocode 4
• Concrete C25/30 (density 2,500 kg/m³) as per ArcelorMittal design basis
• Manufactured by ArcelorMittal Construction and supplied by RMD Profiles

Supply and Design Service

RMD Profiles provides a complete supply and design service for RMD220 projects, including pre-design calculation notes from ArcelorMittal’s engineering office for project-specific spans and loads, full auxiliary item schedules, layout drawings, installation guidance, and specialist installation teams where required.

Given the 3 to 6 week lead time and the installation planning required, early engagement with our team is strongly recommended. Projects that do not begin the technical dialogue until the order stage frequently encounter programme pressure that could have been avoided.

Further Reading and Guidance

• Composite Floor Decking in the UK: Clear Choices, Faster Floors
  A practical guide to composite floor deck selection covering how standard composite profiles compare with long-span solutions like RMD220, and when the span, structural compatibility, or programme requirements make RMD220 the logical choice.
• The Many Uses of Edge Trim in Metal Deck Construction
  Edge trim selection and detailing for metal deck installations. Especially relevant for RMD220 projects where the total slab depth (220mm deck plus Hc) requires larger edge trim sections than standard composite profiles.

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