MetFloor 55 (MF55) Composite Floor Decking – 600mm Cover Width

MetFloor 55 (MF55) Composite Floor Decking

MetFloor 55 (MF55) : Shallow Re-Entrant Composite Floor Deck for Tight Storey Heights and Acoustic Specs

MetFloor 55 (MF55) is a 55mm deep dovetail re-entrant composite floor deck, and one of the most widely specified shallow composite profiles in the UK. The dovetail trough creates a strong mechanical key into the concrete slab, backed by trough stiffeners, delivering reliable composite shear bond performance without reliance on embossments alone.

The virtually flat soffit reduces structural zone depth, simplifies services coordination above suspended ceilings, and means no additional fire protection is required to the beam top flange on qualifying designs. That removes a trade from the programme and a cost from the budget.

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MetFloor 55 prices start from £19/m² (supply only), depending on specification, gauge, and order volume.

MetFloor 55 (MF55) Key Benefits

• 55mm deep dovetail re-entrant profile, 600mm cover width, virtually flat soffit
• 100mm minimum slab depth for 60-minute fire rating with normal weight concrete
• 90% beam top flange coverage in line with SCI P375, meaning no additional fire protection required to the top flange of supporting steelwork on qualifying designs
• Wide trough gives great flexibility and efficiency for shear stud placement
• Recessed service ribs at 150mm centres for wedge nut and service hanger attachment without drilling
• Higher concrete mass than equivalent trapezoidal profiles delivers superior acoustic performance
• Thermally efficient profile: small soffit opening limits heat transfer, easing fire rating attainment
• Unpropped spans in excess of 3.5m achievable
• Available in 0.9mm, 1.0mm, and 1.2mm gauges in S350 or S450 grade
• Available with enhanced coating systems for increased corrosion resistance
• CE and UKCA certified
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MetFloor 55 (MF55) Profile Specification

• Profile depth: 55mm
• Cover width: 600mm
• Pitch: 150mm
• Crown width: 41mm
• Valley width: 133mm
• Available gauges: 0.9mm, 1.0mm, 1.2mm
• Steel grades: S350 or S450

Sectional Properties of MF55

Source: MetFloor 55 product datasheet, RMD Profiles Technical Manual.

Panel Weight Reference (MF55)

Approximate weight of a single MetFloor 55 sheet at 3 metres length and 600mm cover width (panel area = 1.80 m²).

Concrete Volume per m²

Concrete density values used in the MetFloor Technical Manual: normal weight concrete wet 2,550 kg/m³, dry 2,450 kg/m³. Deck and mesh weight not included. Ponding allowance not included.

Fire Performance

The dovetail re-entrant trough presents a very small soffit opening. In a fire, this limits the rate of heat transfer into the concrete section, allowing MetFloor 55 to achieve its fire ratings at much shallower total slab depths than any trapezoidal profile. A 100mm slab achieves both a 30-minute and a 60-minute fire rating with fabric mesh reinforcement. A 125mm slab achieves a 120-minute rating.

MetFloor 55 provides 90% beam top flange coverage with standard installation geometry. This exceeds the 85% threshold referenced in SCI Publication P375, meaning no additional fire protection is required to the top flange of the supporting steel beam on qualifying designs. This can produce a meaningful programme and cost saving on schemes with significant beam lengths.

Minimum slab depths for normal weight concrete. Source: MetFloor 55 product datasheet, RMD Profiles. These values are the same for both fabric mesh reinforcement and FibreDeck fibre-reinforced concrete. Actual minimum slab depths and maximum spans depend on loading, span configuration, and design method. Contact our team to confirm for your specific project.

Service Attachment

Recessed ribs run at 150mm centres along the full length of the MetFloor 55 soffit. These accept wedge nut fixings and compatible service hanger devices, allowing suspended ceilings, ductwork, drainage, and data cabling to be attached directly to the deck soffit after the concrete has cured. No drilling, no hot works permit, no loss of corrosion protection.

The 150mm rib pitch means there is a fixing point available at close intervals anywhere along the floor plate, which simplifies M&E layout planning and gives installation teams flexibility without the need for post-installed anchors.

Why Specify MetFloor 55?

MetFloor 55 is the re-entrant profile for the project where two constraints are working against each other: storey height is tight, and the fire strategy demands a 60 or 90-minute rating without adding depth to the structural zone. A 100mm slab achieves 60 minutes with normal weight concrete. A 110mm slab achieves 90 minutes. The difference between those slab depths and what any trapezoidal profile requires at the same fire rating is the space that MetFloor 55 hands back to the architect or the building programme.

The acoustic case is equally direct. The dovetail trough displaces less concrete from the slab cross-section than a trapezoidal profile at the same total depth. At 120mm total depth, MetFloor 55 requires 0.108 m³/m² of concrete. A 60mm trapezoidal profile at the same depth requires around 0.086 m³/m². That additional 25% of concrete mass per m² contributes directly to airborne sound insulation. On residential and student accommodation schemes where Part E compliance is a design requirement, the MetFloor 55 slab carries more acoustic mass into the design without requiring the slab to be thicker.

The 90% beam top flange coverage is a third independent benefit. It does not depend on a special option or an additional trade. MetFloor 55, installed in its standard configuration, covers the beam top flange to an extent that satisfies the SCI P375 threshold in the vast majority of cases. That means the fire protection sub-contractor does not need to return to intumescent-coat the top flanges, removing both a cost and a programme dependency that can otherwise sit on the critical path.

The wide trough also gives shear stud placement genuine flexibility. On a floor plate where stud positions vary to suit beam orientations and composite ratios, the wide valley means studs can be positioned efficiently without being crowded out by the trough walls. This is a practical benefit that saves time during stud layout and welding.

Typical Applications

• Multi-rise residential towers and apartment buildings where storey height efficiency and acoustic performance are primary design requirements
• Student accommodation, hotel, and healthcare developments where 60 or 90-minute fire ratings must be achieved from the thinnest practical slab
• Education buildings and public sector projects where acoustic performance between floors is a specification requirement
• Refurbishment and extension projects where additional floor depth above existing structure must be minimised
• Any scheme where the removal of beam top flange fire protection is a programme or cost objective

Compliance and Standards

• CE and UKCA certified
• Available in S350 and S450 grades to BS EN 10346
• Fire performance in accordance with SCI P375 for beam top flange coverage
• TAB-Deck fibre-reinforced concrete option available as an alternative to fabric mesh reinforcement
• Enhanced coating systems available for increased corrosion resistance in more aggressive environments
• Supplied in accordance with the BCSA Code of Practice for metal decking and stud welding

Why Choose RMD Profiles?

Since 2009, RMD Profiles has supported thousands of UK contractors, engineers, and developers with dependable roof and floor decking systems. We combine a wide stocked product range with genuine technical expertise, fast-track supply, and a level of service that keeps projects moving.

• One of the widest stocked ranges of structural decking in the UK
• Exclusive Buy Back Scheme for surplus materials
• Certified stud welding and edge trim expertise, in line with BCSA and SCI guidelines
• Fast-track supply with 24-hour delivery available on stocked lines (subject to stock)
• Trusted partner on over 10,000 UK projects, from hospitals to high-rises

Further Reading and Guidance

• Composite Floor Decking in the UK: Clear Choices, Faster Floors
  A practical guide to composite floor deck selection covering how re-entrant and trapezoidal profiles compare in practice, and how storey height, fire rating, and acoustic requirements interact to influence profile choice. Useful if you are weighing up MetFloor 55 against MetFloor 60 or a ComFlor re-entrant profile.
• The Many Uses of Edge Trim in Metal Deck Construction
  Edge trim selection and detailing for metal deck installations, covering slab edge, construction joint, and fire compartmentation applications relevant to MetFloor 55 projects.

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