Dimond Structural Flooring Systems are subject to the environments in which they are used and the type of coating used as outlined in detail below.
Coating Material Specification
Dimond Structural Flooring Systems are manufactured from a galvanised coil in grade Z275 i.e. 275g/m² total galvanised zinc coating weight.
Other grades of zinc coating may be available. Please contact Dimond on 0800 DIMOND (0800 346 663) for guidance.
The durability of galvanised zinc-coated products is dependent on:
- The environment it will be installed in.
- The grade or weight of the zinc coating used.
- The degree and extent of the maintenance that will be undertaken over the life of the product.
Performance of galvanised zinc-coated composite floor slabs is affected by:
- The cumulative effects of the weather to either the underside surface or moisture ingress of the top surface.
- The amount of dust (which can hold moisture) that settles on the product.
- Any other wind-blown deposits that may settle on the product, promoting corrosion.
- Proximity to the ground in subfloor areas with little or no ventilation.
Condensation or other deposits should be prevented from accumulating on the Dimond Structural Flooring System underside by providing adequate ventilation. A protective barrier must be provided if dampness is possible on the underside of the steel decking sheet. Refer to Durability Statement below.
Limitations On Use
The use of galvanised steel decking sheet should be avoided:
- In areas where high concentrations of chemicals are combined with 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.
Refer Durability Statement below for guidance on methods of protection.
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 this 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 Flooring Design 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 of the Flooring Design manual 3.3.5, 3.4.7 and 3.5.7, Dimond Structural Flooring Systems can be designed using this 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 with the New Zealand Building Code should be checked with that product’s manufacturer.
The use of concrete composite floor slabs based on Dimond Structural Flooring Systems is limited to dry and non-corrosive environments unless further protection of the surfaces is provided.
It is the responsibility of the design engineer to assess the durability requirements and specify accordingly.
The top concrete surface may require additional crack control and/or waterproofing if it is to be exposed to moisture, and the underside surface of the steel decking may require additional protection from suitable protective coatings applied in-situ if exposure to moisture, marine deposits or chemicals is expected.
Concrete Surface Treatment
Where the top surface of the composite floor slab is exposed to moisture, use of Dimond Structural Flooring Systems is only recommended if there is an appropriate coating system applied to the top surface of the composite floor slab and fully maintained for the design life of the structure, and/or adequate concrete crack control is achieved. Moisture seeping through cracks which are not effectively sealed can combine with oxygen to the extent that corrosion of the steel decking may occur.
As a guide and subject to designers specification and approval,
- To suppress moisture entering the concrete surface, provide the minimum necessary reinforcement in the composite floor slab and apply a suitable proprietary waterproofing agent (either mixed into the concrete before pouring or sprayed onto the top surface after curing).
- To prevent moisture from entering the concrete, provide the minimum necessary reinforcement in the composite floor slab, and apply a proprietary waterproof membrane to the concrete surface.
Underside Surface Treatment
Where the underside surface of the steel decking may be exposed to contaminants and/or moisture that will not regularly dry out, the use of Dimond Structural Flooring Systems is only recommended if suitable protection of the galvanised steel underside surface can be achieved with a proprietary coating system applied in-situ. Coating specifications and statements on the suitability of use can be obtained from PPG Coatings or Akzo Nobel Coatings.
Dimond Structural Flooring Systems require a minimum degree of maintenance to ensure expected performance is achieved.
As a guide, the following should be carried out as often as is needed (this could be as often as every three months).
- Keep surfaces clean and free from continuous contact with moisture, dust and other debris. This includes areas such as the exposed steel deck underside, e.g. decks or subfloors. Where necessary, regular maintenance should include a wash-down programme to remove all the accumulated dirt or salt buildup on all the galvanised surfaces with a soft brush and plenty of clean water or by water blasting at 15 MPa (2000 psi).
- Ensure any concrete surface cracking exposed to possible water ingress is fully sealed. Similarly, ponding of water on exposed top surfaces must be avoided to ensure durability requirements are met.
- Periodically inspect the steel decking underside. At the first sign of any underside corrosion, the affected areas should be cleaned down, spot primed with a zinc-rich primer and then repainted to an appropriate paint manufacturer's recommendations.
Any cases of severe damage or corrosion must be reported to the structural design engineer.