COMPOSITE FLOORING

Dimond Flooring Systems use a roll-formed profiled galvanised steel sheet as a component in reinforced concrete floor systems.

/ Environment

General Environment

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 flooring products 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 Flooring System underside by providing adequate ventilation. A protective barrier must be provided if dampness is possible on the underside of the steel flooring sheet. 

Limitations of use

The use of galvanised steel flooring sheet should be avoided: 

  • In areas where high concentrations of chemicals are combined with a high humidity, unless an appropriate protective coating system is applied to the underside surface and fully maintained for the design life of the structure. In this situation the system remains wet for long periods of time, causing a 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, unless an appropriate protective coating system is applied to the underside surface and fully maintained for the design life of the structure. For example, where used as the cover slab of a water tank.
  • In or near marine environments, where the prevailing wind carries marine salts, unless an appropriate protective coating system is applied to the underside surface and fully maintained for the design life of the structure.
  • 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, unless an appropriate protective coating system is applied to the underside surface and fully maintained for the design life of the structure. 
  • 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 Malthoid (DPC) between the timber and galvanised steel flooring 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 Flooring Systems if they are compatible with galvanised steel.

Where the top surface of the slab is exposed to moisture, use of the Dimond Flooring System without an appropriate coating system (which is fully maintained for the design life of the structure) and/or adequate crack control to the top surface of the concrete slab should be avoided. Moisture seeping through cracks which are not effectively sealed or which do not have adequate crack control can combine with oxygen to the extent that corrosion of the galvanised steel sheet may occur.

/ Maintenance

Dimond Flooring Systems require a minimum degree of maintenance to ensure expected performance is achieved. Careful maintenance can extend the useful life of the Dimond Flooring System. 

As a guide the following should be carried out as often as is needed (this could be as often as every three months).

  1. Keep surfaces clean and free from continuous contact with moisture, dust and other debris. This includes areas such as exposed undersides, eg decks or subfloors.
  2. Any 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.
  3. Regular maintenance should include a washdown 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).
  4. Periodically inspect the Dimond Flooring System. At the first sign of any underside corrosion, the affected areas should be cleaned down, spot primed and then repainted to an appropriate paint manufacturer’s recommendations. 

Any cases of severe damage or corrosion must be reported to the design engineer

/ General Material Specification

Dimond Flooring Systems are manufactured from galvanised coil in grade Z 275 ie 275 g/m2 total galvanised zinc coating weight.


Grade Z 275 usually requires a three-month lead time from date of order to supply for all thicknesses and quantities. Other grades of zinc coating are available. Please contact Dimond for guidance. 

NZBC Compliance

Past history of use of Dimond Flooring Systems indicate that provided the product use and maintenance is in line with the guidelines of this manual, Dimond 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 Flooring Systems designed using the Fire Design Sections 3.3.6 and 3.4.6 of this manual and HERA Reports R4-82 and R4-131 as appropriate will meet the performance criteria in Clauses C3 and C4 of the New Zealand Building Code.

Unless noted otherwise in the Noise Control Sections (3.3.7 and 3.4.7), Dimond Flooring Systems designed using this manual that are stated to achieve Sound Transmission Class (STC) and Impact Insulation Class (IIC) of 55 meet the requirements of the current New Zealand Building Code (NZBC) Clause G6.

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

For detailed material specification see:

FLATDECK

Flatdeck is a versatile, lightweight composite steel flooring system that makes full use of the combined structural properties of both steel and concrete.

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Scope of use

Dimond Flooring Systems use a roll-formed profiled galvanised steel sheet as a component in reinforced concrete floor systems. The sheet provides both permanent formwork and positive tensile reinforcement in one way reinforced concrete slab construction over concrete block walls, poured concrete beams, steel beams or timber beams, which are subject to environmental limitations referenced to the appropriate grade of material selected. 

It is critical to product performance that the loads applied, spans, formwork material thickness and overall slab thickness are designed within the appropriate Limit State Loads and limitations published in this manual. Before commencing a project using a Dimond Flooring System, the user must refer to the information within this manual and all sections as appropriate, ensuring relevant information is available to the end user. Failure to observe this information may result in a signicant reduction in product performance. Dimond accepts no liability whatsoever for products which are used otherwise than in accordance with these recommendations.

The information contained within Flooring Systems is only applicable to Dimond Flooring Systems –it cannot be assumed to apply to similar products from other manufacturers.

Use outside the stated guidelines

If the need arises to use the Dimond Flooring System outside the limitations and procedures given in this manual or if there exists any doubt on product handling or use, written approval should be obtained from Dimond for the specific project, before the project is commenced.

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Material Specification

Dimond Flatdeck and accessories are manufactured from galvanised steel coil produced to AS 1397:2001.


Base Material Thickness (BMT) (mm) Steel Grade (mPa) Min. Zinc Weight g/m2
Flatdeck sheeting 0.75 & 0.95 G550 Z 275
End cap 0.55 G250 Z 275


Tolerances

Length -0mm +10mm
Sheet cover width -1mm +5mm
Maximum manufactured length of Flatdeck sheet 18m.

Short Form Specification

The flooring system will be Dimond (1)mm Flatdeck manufactured from G550 grade steel, with a 275 g/m2 galvanised zinc weight. The minimum nominal sheet length to be used in construction shall be ............. m, in accordance with the design formwork spans.

Edge forms should be used in accordance with Dimond recommendations.

Specify concrete thickness, and number of rows of propping during construction.

Mesh and any additional reinforcement bar size and spacing should be referred to the design engineer’s drawings.

Choose from:
(1) 0.75, 0.95

/ Design Considerations

Formwork

Where Flatdeck sheet is used as formwork, the profi le provides resistance to wet concrete (G) and construction loads (Q). Maximum formwork spans given in Section 3.4.4.1 Flatdeck Formwork Tables in the structural design manual are based on design checks for bending, web crushing, vertical shear, combined actions and deflection.

Flatdeck sheets must be laid in one continuous length between permanent supports. Short sheets of Flatdeck must never be spliced together to achieve the span between temporary or permanent supports.

Composite Slab

Design capacity of the Flatdeck Flooring System is largely dependent on interaction between the concrete and the Flatdeck sheet commonly referred to as shear bond. Shear bond is a combination of chemical bond between the concrete and the Flatdeck sheet and mechanical bond between the concrete and the vertical ribs of the Flatdeck sheet. This allows tension forces to be transferred from the concrete into the Flatdeck sheet.

Capacities for the Ultimate Limit State were derived for positive bending, shear bond, vertical shear and negative bending as appropriate. Each of these values was back substituted into the design combinations for the applied actions using 1.2 (dead load) + 1.5 (superimposed load).

The minimum resulting superimposed load, from all actions (including deflections), was used in the tables.

Appropriate imposed floor actions (Q) should be determined in accordance with AS/NZS 1170.1.
All superimposed dead load (GSDL) is then added to the imposed action (Q) to give a design superimposed load (GSDL + Q) expressed in kPa for direct comparison with the tabulated data in Section 3.4.5 Flatdeck Composite Slab Load Span Tables in the structural design manual

Fire Design

Fire resistance for the Flatdeck Flooring System may be achieved by several methods. These include placement of additional reinforcement, spray-on insulation retardant, placement of suspended ceilings, and increasing the overall slab thickness. We have considered placement of additional reinforcement in the fire design tables.

This method is based on resistance to collapse (stability), the ability of the Flatdeck floor slab to
prevent fl ames passing through cracks formed in the slab (integrity) and limiting the temperature
increase on the unexposed side of the Flatdeck floor slab (insulation).

The fire design tables are based on design checks for bending (shear is rarely critical), in accordance with NZS 3101, based on the load combination G + ψlQ for single spans which are effective in fire emergency conditions (where ψl is the factor for determining quasi-permanent values for long term actions). Full design methodology is provided in HERA Report R4-82, except that for Flatdeck the contribution of that portion of the steel decking rib that is embedded into the slab and therefore shielded from direct exposure to the fire, is calculated by determining the temperature due to conduction of heat from the exposed pan of the decking.

The rib element is subdivided into 10 elements and the temperature of each element is determined using the method from HERA Report R4-131 Slab Panel Method (3rd edition). The strength at elevated temperature (yield strength as function of temperature) is also determined in accordance with this report. The contribution of each element to the overall moment capacity of the slab is calculated in accordance with normal reinforced concrete design procedures.

The fire design tables include a superimposed dead load (GSDL) of 0.5 kPa in order that an imposed action (Q) can be compared directly with the tables in Section 3.4.6 Fire Design Tables in the structural design manual.

For Flatdeck section properties, formwork design and span capabilities download design guide below.

/
Components

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

The foot of the edge form is fixed to the structure by self-drilling metal screws or powder actuated fasteners. The Flatdeck sheeting may sit on this foot and be fixed to the edge form by rivets or self-drilling metal screws.

Edge Form Support Strap

The top edge is restrained from outward movement (when the concrete is being placed) by a specifically designed 30 x 0.55mm galvanised metal edge form support strap, which is fixed to = the Flatdeck or structure. The straps are normally at 600mm centres.

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Installation

Propping

  • Temporary propping must be placed in position prior to placement of the Flatdeck sheet to provide a safe and solid working platform during the construction phase. As a practical maximum, propping lines should be placed not more than 2.0m apart (for up to 180mm overall slab thickness).
  • Bearers and props must consist of either Machine Stress Graded MSG8 timber for load-bearing situations or structural steel sections sized for the construction loads by the design engineer.
  • A continuous 100mm x 50mm strap fixed to the studs at mid-height attached at one end to a permanent wall is required to avoid buckling of the studs during the concrete pour.
  • Propping lines must have a solid foundation and be cross braced or held in position by nailing through the Flatdeck sheet into the bearer.
  • Bearers used must be a minimum dimension of 100mm x 100mm (2 - 100mm x 50mm on edge nailed together), fully supporting all Flatdeck sheets.
  • Vertical propping varies depending on the slab thickness and maximum height of the propping system.

Slab thicknesses up to 180mm

  • Up to 2.4m maximum height use 100mm x 50mm vertical props at 600mm centres.
  • From 2.4m to 2.7m maximum height use 100mm x 50mm vertical props at 450mm centres.
  • From 2.7m to 3.0m maximum height use 100mm x 100mm (2 - 100mm x 50mm nailed together) at 600mm centres.

Slab thicknesses from 180mm to 300mm

  • Up to 2.7m maximum height use 100mm x 50mm vertical props at 450mm centres.
  • From 2.7m to 3.0m maximum height use 100mm x 100mm (2 - 100mm x 50mm nailed together) at 600mm centres.
  •  All other slab thicknesses and propping systems require specific design by the design engineer
  • If cutting of the Flatdeck sheet is required when forming penetrations, temporary propping is required around the opening to maintain the integrity of the sheet during the concrete pour. The area of Flatdeck removed for penetrations must be replaced by an equivalent strength of reinforcing to the design engineer’s specification. 
  • Penetrations greater than 250mm x 250mm require specific design by the design engineer.

NOTE: the diagram above is representative of a propping system with propping lines placed not more than 2.0m apart for a Flatdeck slab up to 80mm overall thickness with a maximum propping height of 2.4m.

Laying

  • Flatdeck sheets must be laid in one continuous length between permanent supports. Short sheets of Flatdeck must never be spliced together to achieve the span between temporary or permanent supports.
  • The minimum Flatdeck sheet bearing (or seating) onto permanent structure is 30mm. However for steel supports 50mm minimum bearing is recommended, and for concrete/block 80mm minimum bearing is recommended.
  • Align the first Flatdeck sheet with the female edge of the side lap sitting on the permanent support. Apply hold down fixings and lay Flatdeck sheets in the sequence shown.

NOTE: Where the Flatdeck sheet is continuous over multiple steel beams, additional fixing may be required to avoid issues due to wind uplift. Care should be taken with location of fixings to ensure these do not clash with shear stud locations.

Use of self-drilling screws is recommended to control deflections and maintain the integrity of the side lap. As a practical guide, use 10g-16 x 16mm self-drilling screwed mid-span between the permanent supports and temporary propping lines.

  • Where supports are steel beams, shear connectors are welded through the Flatdeck sheets onto the steel beam beneath. Where this is required the top flange of the beam must be unpainted or have the paint stripped clean. Where shear connectors are pre-welded to beams, these must be located in line with the bottom pan of the Flatdeck sheet (300mm centre to centre) in order to gain the required shear capacity.
  • Where fixing into solid filled concrete block (especially when using powder actuated drive pins), edge breakout of the block can be avoided by increasing the Flatdeck sheet bearing (or seating) and fixing into the grout.
  • Where tilt slab construction is being used, the Flatdeck sheets are fixed to a steel angle bolted onto the tilt slab (minimum 50mm seating leg).
  • When laying over timber supports, the Flatdeck sheet must be separated from the timber using Malthoid (DPC) or similar. Galvanised nails must be used to hold down Flatdeck sheets during installation. Permanent shear connectors require specific design by the engineer.
  • Periodic checks should be made on large runs to ensure the sheets are parallel and true to the first sheet. Stretching of the Flatdeck sheet to increase coverage must be avoided.
  • Where on-site cutting of the Flatdeck sheet is necessary, use a metal-cutting power saw or angle grinder. After cutting, all swarf or metal filings must be cleaned off the sheet surface (recommended at the end of each day’s work) to avoid corrosion.

Other considerations

  • Where required, Edge Form is used to contain concrete during the pour. 
  • Mesh and/or additional reinforcing must be placed in accordance with the design engineer’s specifications to ensure minimum top cover. The reinforcing mesh shall be orientated so the top bar runs in the same direction as the steel sheet.
  • Consideration should be given to laying planks as walkways to minimise localised loading of the Flatdeck sheet by foot traffic or equipment.

Concrete Placement

  • Avoid dumping of wet concrete in a heap and when using a concrete pump, ensure the height of the discharge nozzle is not more than 300mm above the top of the Flatdeck sheet. This will avoid overloading of the Flatdeck sheet causing buckling and/or opening of the side laps.
  • Begin the pour over a beam or propping line (shown in the diagram below) to minimise deflections. Spread the wet concrete away from the beams and into the span. Work wet concrete across the Flatdeck sheet towards the underlapping sheet to keep the side laps tightly closed, as illustrated.
  • It is recommended that concrete placers do not crowd together during the pouring sequence, but maintain a one square metre “zone” to avoid overloading the Flatdeck sheet.
  • The use of a concrete vibrator will help eliminate air voids and ensure full contact between the Flatdeck sheet and the concrete.
  • Where the Flatdeck sheet underside is visible, concrete leakage on the underside must be washed off once concrete placement is complete and before the concrete slurry dries off.
  • Temporary propping and formwork should not be removed until the concrete strength has reached 20 MPa, or if this can not be established, 28 days full cure.

HIBOND 55

Hibond 55 is a proven performer in the three key areas of strength, reliability and economy. Hibond is a versatile, lightweight system that delivers rapid and cost-effective installation saving on construction time.

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Scope of use

Dimond Flooring Systems use a roll-formed profiled galvanised steel sheet as a component in reinforced concrete floor systems. The sheet provides both permanent formwork and positive tensile reinforcement in one way reinforced concrete slab construction over concrete block walls, poured concrete beams, steel beams or timber beams, which are subject to environmental limitations referenced to the appropriate grade of material selected. 

It is critical to product performance that the loads applied, spans, formwork material thickness and overall slab thickness are designed within the appropriate Limit State Loads and limitations published in this manual. Before commencing a project using a Dimond Flooring System, the user must refer to the information within this 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 accepts no liability whatsoever for products which are used otherwise than in accordance with these recommendations.

The information contained within Flooring Systems is only applicable to Dimond Flooring Systems – it cannot be assumed to apply to similar products from other manufacturers.

Use outside the stated guidelines

If the need arises to use the Dimond Flooring System outside the limitations and procedures given in this manual or if there exists any doubt on product handling or use, written approval should be obtained from Dimond for the specific project, before the project is commenced.

/
Material Specification

Dimond Hibond and accessories are manufactured from galvanised steel coil produced to AS 1397:2001.

Base Material Thickness (BMT) (mm) Steel Grade (mPa) Min. Zinc Weight g/m2
Hibond sheeting 0.75 & 0.95 G550 Z 275
End cap 0.55 G250 Z 275
Closure strip 0.55 G250 Z 275
Edge Form 1.15 G250 Z 275
Hanger Tab 1.55 G250 Z 275

Tolerances
Length -0mm +10mm
Sheet cover width -1mm +5mm
Maximum manufactured length of Hibond sheet 18m.

Short Form Specification

The flooring system will be Dimond (1)mm Hibond manufactured from G550 grade steel, with a 275 g/m2 galvanised zinc weight. The minimum nominal sheet length to be used in construction shall be ............. m, in accordance with the design formwork spans.

Edge forms and end caps should be used in accordance with Dimond recommendations.

Specify concrete thickness, and number of rows of propping during construction.

Mesh and any additional reinforcement bar size and spacing should be referred to the design engineer’s drawings.

Choose from:
(1) 0.75, 0.95

/
Design Considerations

Formwork

Where Hibond sheet is used as formwork, the trapezoidal shape of the profi le provides resistance

to wet concrete (G) and construction loads (Q). Maximum formwork spans given in Section 3.3.4.1
Hibond Formwork Tables in the structural design manual are based on design checks for bending, web crushing, vertical shear, combined actions and deflection.

Hibond sheets must be laid in one continuous length between permanent supports. Short sheets
of Hibond must never be spliced together to achieve the span between temporary or permanent
supports.

Composite Slab

Design capacity of the Hibond Flooring System is largely dependent on interaction between the concrete and the Hibond sheet commonly referred to as shear bond. Shear bond is a combination of chemical bond between the concrete and the Hibond sheet and mechanical bond between the

 concrete and the embossments in the webs of the Hibond sheet. This allows tension forces to be transferred from the concrete into the Hibond sheet.

Capacities for the Ultimate Limit State were derived for positive bending, shear bond, vertical shear and negative bending as appropriate. Each of these values was back substituted into the design combinations for the applied actions using 1.4 (dead load) + 1.6 (superimposed load).

The minimum resulting superimposed load, from all actions (including deflections), was used in
the tables.

Appropriate imposed floor actions (Q) should be determined in accordance with AS/NZS 1170.1.
All superimposed dead load (GSDL) is then added to the imposed action (Q) to give a design superimposed load (GSDL + Q) expressed in kPa for direct comparison with the tabulated data in Section 3.3.5 Hibond Composite Slab Load Span Tables in the structural design manual.  

Fire Design

Fire resistance for the Hibond Flooring System may be achieved by several methods. These include placement of additional reinforcement, spray-on insulation retardant, placement of suspended ceilings, and increasing the overall slab thickness. We have considered placement of additional reinforcement in the fire design tables.

This method is based on resistance to collapse (stability), the ability of the Hibond floor slab to

prevent flames passing through cracks formed in the slab (integrity) and limiting the temperature
increase on the unexposed side of the Hibond floor slab (insulation).

The fire design tables are based on design checks for bending (shear is rarely critical), in accordance with NZS 3101, based on the load combination G + ψlQ for single spans which are effective in fire emergency conditions (where ψlis the factor for determining quasi-permanent values for long term actions). Full design methodology is provided in HERA Report R4-82.

The fire design tables include a superimposed dead load (GSDL) of 0.5 kPa in order that an imposed action (Q) can be compared directly with the tables in Section 3.3.6 Fire Design Tables in the structural design manual

For Hibond 55 section properties, formwork design and span capabilities download design guide below.

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Components

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

The foot of the edge form is fixed to the structure by self-drilling metal screws or powder actuated fasteners. The Hibond sheeting may sit on this foot and be fixed to the edge form by rivets or self-drilling metal screws.

Edge Form Support Strap

The top edge is restrained from outward movement (when the concrete is being placed) by a specifically designed 30 x 0.55mm galvanised metal edge form support strap, which is fixed to the Hibond or structure. The straps are normally at 600mm centres.

Rake Cut Edge Flashings

Manufactured from 0.55mm BMT galvanised steel in 55mm x 30mm x 3m lengths which are cut to suit on site (as shown). Rake cut edge flashings are used in place of end caps to close off the end of Hibond sheets when they are cut on an angle or curve. These are cut to length then fixed to the Hibond sheet with 1 fastener per rib (10 gauge – 16 x 16mm hex head self-drilling screw).

End Caps

Manufactured from 0.55mm BMT galvanised steel, end caps are used to blank off the ribs (to prevent concrete leakage) at the end of each Hibond sheet, or where openings are created in the deck. The cap should be secured to the Hibond by 10 gauge – 16 x16mm hex head self-drilling screws.

Hanger Tabs

Manufactured from 1.55mm BMT galvanised steel, the tabs provide a suspension point for ceiling systems, pipework, ducting or electrical trays onto the underside of the Hibond sheet. The hanger tab is attached by inserting it into, and parallel to the dovetail groove running down the centre of each Hibond sheet. It is then rotated through 90° and sits down in the groove. The serviceability (safe) load for a standard hanger is 1.25 kN.

/ Installation

Propping

  • Temporary propping must be placed in position prior to placement of the Hibond sheet to provide a safe and solid working platform during the construction phase. As a practical maximum, propping lines should be placed not more than 2.0m apart (for up to 180mm overall slab thickness).
  • Bearers and props must consist of either Machine Stress Graded MSG8 timber for load-bearing situations or structural steel sections sized for the construction loads by the design engineer.
  • A continuous 100mm x 50mm strap fixed to the studs at mid-height attached at one end to a permanent wall is required to avoid buckling of the studs during the concrete pour.
  • Propping lines must have a solid foundation and be cross braced or held in position by nailing through the Hibond sheet into the bearer.
  • Bearers used must be a minimum dimension of 100mm x 100mm (2 - 100mm x 50mm on edge nailed together), fully supporting all Hibond sheets.
  • Vertical propping varies depending on the slab thickness and maximum height of the propping system.

Slab thicknesses up to 180mm

  • Up to 2.4m maximum height use 100mm x 50mm vertical props at 600mm centres.
  •  From 2.4m to 2.7m maximum height use 100mm x 50mm vertical props at 450mm centres.
  •  From 2.7m to 3.0m maximum height use 100mm x 100mm (2 - 100mm x 50mm nailed together) at 600mm centres.

Slab thicknesses from 180mm to 300mm

  • Up to 2.7m maximum height use 100mm x 50mm vertical props at 450mm centres.
  • From 2.7m to 3.0m maximum height use 100mm x 100mm (2 - 100mm x 50mm nailed together) at 600mm centres.
  • All other slab thicknesses and propping systems require specific design by the design engineer.
  • If cutting of the Hibond sheet is required when forming penetrations, temporary propping is required around the opening to maintain the integrity of the sheet during the concrete pour. The area of Hibond removed for penetrations must be replaced by an equivalent strength of reinforcing to the design engineer’s specification.
  • Penetrations greater than 250mm x 250mm require specific design by the design engineer.

NOTE: The diagram above is representative of a propping system with propping lines placed not more than 2.0m apart, for a Hibond slab up to 180mm overall thickness with a maximum propping height of 2.4m.

Laying

  • Hibond sheets must be laid in one continuous length between permanent supports. Short sheets of Hibond must never be spliced together to achieve the span between temporary or permanent supports.
  • Hibond end caps are fitted at sheet ends to avoid concrete leakage. Fit the end caps after the Hibond sheets have been laid and fixed in place. Self-drilling screws are used to secure end caps in position via a pre-punched locating hole.
  • The minimum Hibond sheet bearing (or seating) onto permanent structure is 30mm. However for steel beams 50mm minimum bearing is recommended, and for concrete/block 80mm minimum bearing is recommended.
  • Align the first Hibond sheet with the male edge of the side lap sitting on the permanent support. This will ensure the side laps fit correctly together. Apply hold down fixings and lay Hibond sheets in the sequence shown.
  • Where supports are steel beams, shear connectors are welded through the Hibond sheets onto the steel beam beneath. Where this is required the top flange of the beam must be unpainted or have the paint stripped clean. Where shear connectors are pre-welded to beams, these must be located in line with the bottom pan of the Hibond sheet (305mm centre to centre) in order to gain the required shear capacity.
  • Where fixing into solid filled concrete block (especially when using powder actuated drive pins), edge breakout of the block can be avoided by increasing the Hibond sheet bearing (or seating) and fixing into the grout.
  • Where tilt slab construction is being used, the Hibond sheets are fixed to a steel angle bolted onto the tilt slab (minimum 50mm seating leg).
  • When laying over timber supports, the Hibond sheet must be separated from the timber using Malthoid (DPC) or similar. Galvanised nails must be used to hold down Hibond sheets during installation. Permanent shear connectors require specific design by the engineer. Periodic checks should be made on large runs to ensure the sheets are parallel and true to the first sheet. Stretching of the Hibond sheet to increase coverage must be avoided.
  • Where on-site cutting of the Hibond sheet is necessary, use a metal-cutting power saw or angle grinder. After cutting, all swarf or metal filings must be cleaned off the sheet surface (recommended at the end of each day’s work) to avoid corrosion.

Side Lap Stitching

  • Self-drilling screws are the preferred method for side lap stitching of Hibond sheets. As a practical guide, use 10g - 16 x 16mm self-drilling screws at maximum of 600mm centres.
  • As an alternative Hibond sheet side laps can be crimped together at a maximum of 350mm centres along the full lap length, using the specialised crimping tool. Call your local representative on 0800 DIMOND (346 663) to arrange a crimping tool.
  • Crimping is carried out using the following method:

Other Considerations

  • Where required, Edge Form and Closure Strip (rake edge fl ashing) are used to contain concrete during the pour. 
  • Mesh and/or additional reinforcing must be placed in accordance with the design engineer’s specifications to ensure minimum top cover. The reinforcing mesh shall be orientated so the top bar runs in the same direction as the steel sheet.
  • Consideration should be given to laying planks as walkways to minimise localised loading of the Hibond sheet by foot traffic or equipment.

Concrete Placement

  • Avoid dumping of wet concrete in a heap and when using a concrete pump, ensure the height of the discharge nozzle is not more than 300mm above the top of the Hibond sheet. This will avoid overloading of the Hibond sheet causing buckling and/or opening of the side laps.
  • Begin the pour over a beam or propping line (shown in the diagram below) to minimise deflections. Spread the wet concrete away from the beams and into the span. Work wet concrete across the Hibond sheet towards the underlapping sheet to keep the side laps tightly closed, as illustrated.
  • It is recommended that concrete placers do not crowd together during the pouring sequence, but maintain a one square metre “zone” to avoid overloading the Hibond sheet.
  • The use of a concrete vibrator will help eliminate air voids and ensure full contact between the Hibond sheet and the concrete.
  • Where the Hibond sheet underside is visible, concrete leakage on the underside must be washed off once concrete placement is complete and before the concrete slurry dries off.
  • Temporary propping and formwork should not be removed until the concrete strength has reached 20 MPa, or if this can not be established, 28 days full cure.