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Dimond Flatdeck Composite Steel Flooring System

Flatdeck is a versatile, lightweight composite steel flooring system that makes full use of the combined structural properties of both steel and concrete. The result is a strong, stable and durable residential/commercial floor — a floor which provides thermal storage, soundproofing and fire resistance.

Flatdeck is a 57mm deep tray flooring profile used where thinner slabs are required and/or where underside appearance is important. Designed in accordance with the procedures in AS/NZ 4600, AS 3600 and BS 5950 based on detailed analysis and physical testing.

Flatdeck is roll-formed from high strength zinc-coated steel coil to AS1397, available in 0.75mm and 0.95mm thicknesses. Flatdeck is supplied with a range of compatible components including Edge Form.

Key Features
  • Self-locking laps and minimal components make for quick and simple installation
  • Lightweight sheets are ideal for remote or difficult access sites
  • Flat soffit appearance allows use as exposed ceiling for modern industrial look
  • Economic alternative to poured slab on hard fill for sloping sites
  • Excellent acoustics and fire performance
  • Residential and commercial projects
NZ Made
NZ Made
NZ-Owned Business
NZ-Owned Business
Scope of Use
  • Dimond Structural Flooring Systems use a roll-formed profiled galvanised steel sheet as a component in reinforced concrete floor systems
  • The steel decking sheet provides both permanent formwork and positive tensile reinforcement in one way reinforced composite floor slab construction over concrete block walls, poured concrete beams, steel beams or timber beams, subject to the environmental limitations referenced to the appropriate grade of the material selected
  • It is critical to product performance that the loads applied, spans, formwork material thickness and overall composite floor slab thickness are designed within the appropriate Limit State Loads and limitations published in the Flooring Systems Design Manual
  • Before commencing a project using a Dimond Structural Flooring System, the user must refer to the information within the manual and all sections as appropriate, ensuring relevant information is available to the end-user. Failure to observe this information may result in a significant reduction in product performance
  • Dimond Structural accepts no liability whatsoever for products which are used otherwise than in accordance with these recommendations
Limitations on Use

The use of galvanised steel decking sheet should be avoided:

  • In areas where high concentrations of chemicals are combined with a high humidity, where the system remains wet for long periods of time, causing rapid consumption of the galvanised zinc coating and eventual red rusting of the base metal.
  • Where the galvanised surface is being exposed to continuous moisture, without a chance for the surface to dry out for example, where the composite floor slab covers a water tank.
  • In or near marine environments, where the prevailing wind carries marine salts which deposit on the steel decking, causing rapid consumption of the galvanised zinc coating and eventual red rusting of the base metal.
  • In areas surrounding chemical or industrial storage buildings where any chemical attack may lessen the life of the structure or wind-driven chemical fumes may attack the galvanised coating.
  • When in contact with or laid directly on ground.
  • When in contact with timber and especially treated timber such as CCA (copper chrome arsenic) without the use of an isolating material such as DPC between the timber and galvanised steel decking sheet.
  • When used in sub-floor areas with less than 450mm ground clearance.
  • When used in sub-floor areas where ventilation does not comply with NZS 3604 Clause 6.14.

Chemical admixtures may only be used with Dimond Structural Flooring Systems if they are compatible with galvanised steel.

Statement of Building Code Compliance

Past history of use of Dimond Structural Flooring Systems indicate that provided the system design, product use and maintenance is in line with the guidelines of the Flooring Systems Design Manual, Dimond Structural Flooring Systems can reasonably be expected to meet the performance criteria in Clause B1 Structure and B2 Durability of the New Zealand Building Code for a period of not less than 50 years, provided they are kept free from moisture.

Dimond Structural Flooring Systems designed using the Fire Design Sections 3.3.4, 3.4.6 and 3.5.6 of the manual and will meet the performance criteria in Clauses C3 and C4 of the New Zealand Building Code (section 3.3.4 is based on testing to EN 1365-2 and sections 3.4.6 and 3.5.6 are based on HERA reports R4-82 and R4-131).

Using the Flooring Acoustic Performance sections 3.3.5, 3.4.7 and 3.5.7, Dimond Structural Flooring Systems can be designed using the manual for guidance to achieve Sound Transmission Class (STC) and Impact Insulation Class (IIC) of 55 meet the requirements of the current New Zealand Building Code Clause G6, airborne and impact sound.

Where products used in Dimond Structural Flooring Systems are manufactured by other suppliers, compliance to the New Zealand Building Code should be checked with that product’s manufacturer.

In-Service History

Dimond is New Zealand's largest manufacturer of steel roofing, cladding, structural and rainwater goods.

B1 Structure compliant
B2 Durability compliant
C Protection from Fire compliant
Protection from Fire
G6 Airborne and Impact Sound compliant
Airborne and Impact Sound
CAD Downloads
Flooring Systems Design Manual
Specification Clause (Masterspec)
Additional Information

As part of the Fletcher Steel family, Dimond Structural offer technical expertise backed by a history of supplying purlins and composite steel decking in to a range of major New Zealand projects.

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