• 0.75mm
  • 2.9kg
Steel Grade
  • G550
Min. Zinc Weight (g/m2)
  • Z 275
Max. Manufactured Length
  • 18m
  • Edge Form
DIMST Flatdeck Flooring 2


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.

Materials and Components

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
Material Specification

Material Specification

Dimond Flatdeck and accessories are manufactured from galvanised steel coil produced to AS 1397.

BMT (mm)
Steel Grade
Min. Zinc Weight
Flatdeck sheet
BMT (mm)
0.75 & 0.95
Steel Grade
Min. Zinc Weight
Z 275
Edge form
BMT (mm)
Steel Grade
Min. Zinc Weight
Z 275

BMT - Base Metal Thickness


Length -0mm +10mm
Cover width -1mm +5mm
Maximum manufactured length of Flatdeck sheet: 18m



Edge Form

Manufactured from 1.15mm Base Metal Thickness (BMT) galvanised steel in 6m lengths, providing an edge to screed the concrete to the correct composite floor slab thickness.

Standard sizes are from 110mm to 200mm in 10mm height increments.

The foot of the Edge Form is typically fixed to a structure using powder-actuated fasteners (self-drilling screws can also be used, type dependent on support material and thickness).

Where necessary, for example, cantilevered steel decking sheets, the foot of the Edge Form may be attached to the Flatdeck sheets with 10g - 16 x 16mm self-drilling screws. Fasteners are required every pan to steel decking sheet ends and at 750mm centres along the steel decking sheets.

Edge Form Support Strap

Edge Form is restrained from outward movement during concrete placement by 0.75mm BMT x 25mm galvanised steel Edge Form Support Straps. Fastened with 10g - 16 x 16mm self-drilling screws (2 per strap), Edge Form Support Straps are required every second rib to steel decking sheet ends and at 750mm centres along the steel decking sheets.


Specific Design

The Flatdeck Flooring System has been designed to comply with AS/NZ 4600 for formwork strength, AS 3600 for composite floor slab strength and BS 5950 for formwork and composite floor slab deflections, using the relevant load combinations therein and the relevant clauses of the New Zealand Building Code. Detailed analysis and physical testing have enabled load/span tables to be established using the limit states design philosophy.

Data presented in the Flooring Systems Manual is intended for use by structural engineers. Use of the Flatdeck Flooring System in applications other than uniformly distributed loads or outside the scope of this manual will require specific design.

A design yield strength of 550MPa for 0.75mm and 0.95mm base metal thickness (BMT) Flatdeck has been used.

A minimum 28-day compressive strength of 25MPa for high-grade concrete has been assumed.

A minimum Flatdeck composite floor slab thickness of 110mm has been used in this section, in accordance with BS 5950.

The self-weight of the Flatdeck Flooring System (including the concrete) has been included in the load tables.

For full design considerations, refer to 3.5.2 Flatdeck Design Considerations in Flooring Design Manual

Load Spans

Load Span Tables

Download Flatdeck Load Span Tables

Click to downloadUpdated January 2022

Flooring Systems Durability

View Dimond Structural Flooring Systems durability statement

CAD Details

Relevant Product CAD Details

Below you will find all of the relevant product CAD technical details in .dwg, .pdf & .rvt format.

If you have any questions regarding the details below please contact one of our technical team on 0800 550 660

Download all .dwg filesLast updated March 2020
Download all .pdf filesLast updated May 2020
Flooring Design Manual
Material Specification
Section Properties
Flatdeck Brochure

Product Brochure

Need a brochure for this product? Here you can download one with the basic information and details you need during the decision process.

Download Product BrochureLast updated March 2022