Properties and Advantages of the NRG Greenboard Walling System

NRG Greenboard panel is manufactured from high density, rigid, expanded polystyrene. The raw material is gained as a by-product of the manufacture of oil.

Greenboard is manufactured without the use of CFC’s and does not contain or emit any poisonous gas. In  fact, NRG  Greenboard  is made  up of 98%  air entrapped  in  a  closed
cellular structure of polystyrene. This entrapped air accounts for the extremely good insulation properties of the Greenboard.

The off cuts of NRG Greenboard can be glued within the wall cavity prior to the installation of the internal linings as additional insulation. This cuts down on the impact to our environment as all the material is being used, leaving a minimal amount of material to be removed from site.

Insulation for Energy Efficient Buildings

The Greenboard system is the most cost efficient method of insulation in terms of R-value per dollar. Unlike some other methods of insulation that allow thermal bridging across the timber or steel studs framing. NRG Greenboard provides a continuous insulative sheath around the entire building.

Warranty – 10yr

NRG warrants that the Greenboard sheets (the “Product”) will be free from defects due to defective factory workmanship or materials prior to the installation of the Product for a period of 10 years from the date of purchase, subject to compliance with the conditions published in NRG Product Warranty 2007

 Easy to Render

The surface of the NRG Greenboard is grooved providing an excellent substrate for  Reinforced Render Systems.

Energy Efficient Production

Greenboard uses much less energy in its production than conventional building materials such as concrete and masonry

Fashionable Render Finishes

Available in a wide range of Architectural colours and styles (Refer to your selected manufacturers, texture coating specifications).

Design Freedom

Curved walls, rounded corners, embossed patterns, raised wall areas, mouldings and other architectural features are simple to achieve and cost-effectively with the versatile NRG Walling System.

 Vermin Retardant

NRG Greenboard is impregnated with a natural insect retardant, (Bithentrin)

 Biologically Inert

The board will not rot and provides no nutritive value for insects or micro-organisms.

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NRG Greenboard Installation Procedure

Installation Procedures NRG Greenboard Walling System
This manual provides information on the correct procedures and materials to be used for the installation of NRG Greenboard Walling System over standard framed and solid structures. The drawings and details are provided to assist building designers in specifying the correct design and detail of the NRG Walling System. These details cover most common applications. If the details are to be altered or new ones proposed please contact NRG to discuss the changes. Failure to do so may void the systems warranty.

These components that make up the NRG Greenboard Insulative Walling System are.

• Screws and washers
• Vapor permeable sarking
• NRG Greenboard
• NRG PVC beads
• Polymer modified render
• Reinforced mesh
• Texture top coat

These components form part of the complete system and must not be substituted with other possible nonconforming materials.

Timber and Steel Framing
All timber and steel framing should conform to the relevant Australian Standards, as well as the local standards for structural requirements including wind loadings and bracing.

NRG Greenboard is not a structural material and therefore should not be considered or used as a bracing material.

Existing framing
When ‘over-cladding’ existing timber buildings, inspection should be carried out by a fully qualified person, to identify any deterioration or infestation by wood boring insects. Although NRG Greenboard is impregnated with an effective insect repellent, it will not arrest or prevent further infestations of the timber framing structure. Where necessary, repairs must be undertaken to ensure that the timber substrate is sound, straight and true.

Back Blocking (Off Stud Joints)
Where horizontal fixing of sheets ‘off stud’ join are to be made, it is necessary to back block as follows.

i. By fixing an ‘off cut’ of stud  material vertical, (widest face facing outwards) and  securely
nailing to bottom plate and noggin. Alternatively, between noggin and top plate, making sure to glue both Greenboard sheet edges with Bostik No-More Nails and fixing through each sheet into the ‘black block’ with washers and screws at maximum 300mm centre’s.

ii. Alternatively, horizontal ‘back block’ using ‘off cuts’ can be placed at maximum 300mm centre’s, following the above procedure except that, with the two sheets in place, take ‘off cuts’, smear with Bostik No-More Nails over one face, place ‘off cuts’ against the Green board sheets and screw through face of Greenboard into ‘off cuts’, pulling both sheets into alignment.

Solid Blocking of Fitting and Accessories
Consideration should be given to the installation of wall mounted accessories i.e. taps, electrical fittings, etc. It is important to allow for adequate backblocking for these items prior to the installation of the NRG Greenboard.

Electrical Cables and PVC
Cables penetrating the NRG Greenboard Walling System must be installed in conduit or ducts sealed to the cladding or have a sheathing containing migration resistant plasticizer. Cable manufacturers should be contacted for details of suitable cable types.

All flashing to wall openings, roof sections and parapets etc. to be installed prior to the fixing of NRG Greenboard Walling System and is always capped off at the bottom edge of the Greenboard sheet using a Starter Bead  in accordance with good building practice and together with any requirements of the BCA. NRG Building Systems take no responsibility or liability for flashing or installations.

Fitting NRG Greenboard Walling Panels

I. Before commencing to fix panels check that the frames are straight, all windows and flashings are correctly installed and solid backing blocks are in place where required.

II. Timber frames must have a moisture content of less than 15% before Greenboard panels are fitted, horizontally (preferred) or vertically.

III. Measure and cut Greenboard Sheeting using a straight edge and masonry diamond blade in a standard power saw (use of handsaw not recommended).

IV. Glue both horizontal and vertical Greenboard sheet edges to each adjoining sheet using
Bostik – No More Nails / Power trigger foam.

V. Fixing NRG washers and screws at 450mm stud spacings horizontally and 300mm spacings vertically (see fixing table for hight spacings) : -Greenboard sheet lay horizontally, comprising of five (5) rows fixings vertically.
1st – When making butt joint, each sheet is fixed individually to the back-blocking or vertical noggin, corresponding with the above fixing set out.

VI. ‘Infill’ small areas with Greenboard (e.g. above and below windows, etc.) – It is
recommended to use a minimum height of 300mm to allow for adequate fixing.

VII. Allow 3mm gap between Greenboard panel and openings for bead and sealing procedure ((Refer Table 17.1.15 Beading))

VIII. External corners – Greenboard sheets are overlapped the full thickness of the sheet and glued using recommended construction adhesive.

Curved walls
40mm and 60mm Greenboard panels can be fitted to curve walls with a radius greater than 2-4 metres’. Where a tighter radius is required use multiple layers by laminating 2 x 20mm thickness Greenboard panels (off set joints).

Expansion Joints

Expansion joints allow for movement within the building and avoid unsightly cracking within the wall areas. Expansion joints must be provided where NRG Greenboard lengths exceed specified dimensions (see table). In addition, it allows for affording an opportunity to ‘weather seal’ such junctions.



NRG Greenboard Specifications

Fixings – Accessories

Cutting and Tools Required

Gluing and Sealing


NRG have a full range of UV stabilized PVC beads specifically designed for Greenboard cladding .use only UV stabilized beads for external application.
N.B. External and internal ‘rail edges’ must be precise to ensure a uniform complete ‘fit and finish’ in readiness for sealing as well as rendering.

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NRG Greenboard Bead and Sealant Procedure

Installing, Priming and Sealing of Bead – Procedure. N.B. Use only UV stabilized beads for external application.
At this point particular care needs to be exercised to ensure that the installation of all beading around window, door openings etc.; it is imperative that this procedure is performed correctly. This is not just a gap filling exercise but an integral part of the total NRG Greenboard Walling System.

• External and internal ‘rail edges’ must be precise to ensure a uniform complete ‘fit and finish’ in readiness for sealing as well as rendering.
• Extra care needs to be taken to make sure all ‘beads’ are both ‘plumb/level’.
• Priming (to prevent ‘roll-back’ of sealant) and sealing procedure stage requires extreme attention to detail to ensure water tightness of all windows, doors and openings.
• Using Bostik Primer 5077, and a clean rag, dampen cloth with primer and quickly clean the internal joinery to NRG line that is to be sealed.
• Using masking tape, accurately adhere to frame of joinery, 4mm form edge creating a neat parallel margin, ready for sealant application.
• Cut a medium size end off nozzle of ‘Seal’n Flex.’ Proceed in applying sealant. Using a coving tool, neatly create an internal cove finish.
• Remove masking tape from joinery leaving a 100% water proof joint seal.

I. External Corner Angles Beads – External Points of the building, columns etc.

a) Install external corner angle bead to external corner edges by applying a ‘liberal’ bead of
Bostik ‘No More Nails’ to both sides of internal corner rails of the external corner angle bead, then press bead firmly into position. Make sure it is plumb, scraping of excess glue protruding through bead perforations (priming of beads in this case is not required).

II. External Corner Beads – Render return to windows and doors – head, jamb and sills. This is particularly recommended for 60mm, 75mm and 100mm Greenboard.

a) Allow 3mm gap between Greenboard panel and openings (this will provide a ‘key’ for the sealant). Tape around window and door perimeters.

b) Prime and tape around aluminum surfaces of window and door component edges prior to rendering, apply a bead of sealant into the ‘gap’ between the Greenboard and the component edge. This sealing process is repeated after rendering and prior to the
texture painting system

c) Install external corner angle bead to external corner edges. Refer I. a) above.

III. Reveal Beads/Render Reveal Trims (sill) return to head, jamb and sills of windows and doors.

a) Allow 3mm gap between Greenboard panel and openings (this will provide a ‘key’ for the
sealant). Tape around window and door perimeters, priming both surfaces.

b) Prime (using Bostik Primer 5077) beads and tape around surfaces of windows and doors in readiness for application of the texture painting system.

IV. Render Reveal Trim (Sill) – 40mm

a) Allow 3mm gap, prime beads and tape around surfaces of window and door edges prior to sealing readiness for application of the texture paint system.

V. Expansion Joint – there are two options available – Either by using Reveal Beads or Render Expansion Joint.

1) Reveal Beads 

a) Install ‘reveal bead’ to both edges of Greenboard by applying a ‘liberal’ bead of Bostik ‘No More Nail’, allowing a 6mm gap between both sheets, then insert a 10mm foam
backing rod as shown.

b) Prime (using Bostik Primer 5077) both top and bottom outside exposed edges before applying sealant thus creating an ‘expressed’ joint as shown.

2) Expansion Joint Bead (illustration shown in Accessories)

a) Install ‘render expansion joint’ between both Greenboard surfaces (leaving required gap). Applying two beads of Bostik ‘No More Nail’ to either side of the internal corner rails (i.e. top and bottom sections), with sufficient glue to allow the glue to penetrate perforated rail edges. Scrape off excess.

b) Prime (using Bostik Primer 5077) within the ‘flexible’ joint, before applying the sealant thus creating an ‘expressed’ joint.


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NRG Greenboard Walling System over Concrete and Masonry Wall Surfaces

1.  Preparation
All walls must be clean and dust free from dirt, oil, vegetation, and crumbling or loose materials.

2.  Installation of Greenboard using Power’s Foam Adhesive System

i. When installing via the Foam adhesive system, apply a large “dob” of foam adhesive to the middle of each and every masonry block.
ii. Position the board and drill 8mm hole through the masonry at each corner offset in by approx 100mm.
iii. Hammer the Hilti IDP anchors in.
iv. Use a minimum of 8 IDP anchors for each 2500 x 1200 board with at least 2 x IDP anchors staggered in the mid section of the board.

3.  Final Checking of Greenboard installation on Concrete and Masonry Walls – Before rendering, any irregularities in the surface of the sheet or joints are sanded back using a coarse rasp.

4.  Expansion Joints within The Greenboard installation on Concrete and Masonry Walls – All expansion joints in the substrate must be carried through the complete cladding system.

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NRG Greenboard Render Specifications

1.  3.5mm Render
Option 1
1 coat polymer modified render (3.0mm)
Reinforced Alkali Resistent Fibreglass Mesh (160g/mm)
1 coat Acrylic Render (1.0mm)
2 coats of Acrylic Membrane Paint

Option 2
1 coat polymer modified render (3.0mm)
Reinforced Alkali Resistent Fibreglass Mesh (160g/mm)
1 coat Primer
1 coat Timted texture (1.0mm)
(Clearcote optional)

6mm Render
1 coat polymer modified render (4mm)
Reinforced Alkali Resistent Fibreglass Mesh (160g/mm)
1 coat polymer modified render (2mm)
2 coats of Acrylic Membrane Paint

NOTE: To be used only as a guide. Refer to Render/ Paint manufacturers specifications (example Rockcote RRR) for exact details and procedures.

2.   Handling and Storage
i. NRG Greenboard should be laid flat with edges and corners protected from damage.
ii. NRG Greenboard should not be stored in the open or fixed to a building for prolonged periods. NRG Greenboard should to be protected from exposure to direct sunlight and
kept away from extreme heat and organic solvents.

3.   Health and Safety
i. NRG Greenboard Insulative Walling System and is non-hazardous.
ii. However, as with all composite materials basic safety clothing and gloves are  to be worn when handling or cutting the NRG Greenboard.

iii. When cutting NRG Greenboard Insulative Walling System with a power saw it is recommended that a face mask and protective glasses be worn.

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NRG Greenboard Principal Contractor / Builder / Installer

Essential Related Trade Practices

• General Construction and Flashing Principles must be adhered to in maintaining water tightness. NRG Building Systems cannot be held liable for inferior flashing and installation practices.

• It is essential that all external surfaces of the framing structure are parallel, i.e. ground floor framing, mid floor framing and upper floor framing with no protrusions or setbacks. It is also a recommendation that where ply bracing is fixed externally, counter battens be fixed perpendicular to adjoining studs to level the wall surface prior to fixing Greenboard.

• It is imperative that all exterior window/door and joinery are fixed into position prior to the installation of the NRG Greenboard to maintain water tightness and those components are fixed off plumb and level.

• Consideration should be given to the installation of wall mounted accessories i.e. taps, electrical fittings, etc. It is important to allow for adequate back-blocking for these items prior to the installation of the NRG Greenboard.

• Termite Barriers: It is the builder’s responsibility to arrange the installation of a suitable termite barrier system by a qualified professional installer, prior to the installation NRG

• Internal Lining Fixing: If render application has been completed prior to plasterboard/wet area linings installation, it must be screw fixed to the internal side of all external wall surfaces. Failure to do so can result in defects to exterior render surface finish.

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Greenboard Advantages CodeMark Certification & ENVIRONMENT

Greenboard is an Insulated Wall Panel that combines exterior cladding with insulation so designers can achieve the 6 star energy ratings that have been introduced into the building code. Greenboard‘s insulated core of high quality expanded polystyrene puts the Greenboard insulated panel in the best place of the building, as far towards the outer side as possible.

Greenboard Insulated Wall Panel is a lightweight, energy efficient product and once coated the system provides a weather resistant, seam free rendered finish.

Greenboard Advantages

CodeMark Certification

All building products must comply with the BCA (Building Code of Australia). NRG Building Systems has achieved CodeMark on Greenboard Insulated Wall Cladding meaning Greenboard complies to the BCA.

Insulation Qualities

All insulation materials are rated for their performance in restricting heat transfer. This rating is expressed as an R-value which is a measure of the material’s resistance to heat transfer (thermal resistance). The higher the R-value the greater insulating effect.

Sound Rating

NRG Building Systems has tested 60mm Greenboard total wall system and the acoustic performance result was Rw35, Ctr-6. Please refer to NRG test results. The Greenboard walling system can be further enhanced by using a “sound rated” insulation batt. Please refer to insulation manufacture’s specifications.

Fire Retardant

Greenboard contains a flame retardant additive and will not support fire, it has a spread of flame index of zero. If in a fire situation the toxic fumes are no greater than that of timber and other building materials.

Grooved Panel

The surface of the Greenboard panel is Grooved both sides allowing the inside surface to breathe and channel any possible condensation away through the Grooves, downwards to the base of the wall. This is particularly important where “insulation” or “breather sarking” is used. The additional advantage being that when the Grooved face of Greenboard is rendered the system becomes stronger as the render gets into the Groove to form a core shape for better adhesion and a stronger more rigid Greenboard system.

Easy to Use

Greenboard‘s lightweight panel size is 2500 x 1200 allowing installers to cover the external walls quicker and easier. For the builder and their client, Greenboard gets the project to lock up stage quicker allowing other trades to start and complete their tasks.

Greenboard requires less energy to produce than other traditional building materials and contains no CFC’s nor HCFC’s. Greenboard does not contain ozone depleting substances and none are used in the manufacturing of this product. Greenboard can be recycled or NRG recommends left over Greenboard can be placed in the walls as extra insulation.

Greenboard contains a termite retardant (Bifenthrin) and NRG uses 62% more in their product than the minimum required.

Render Levels of Finish

Reinforced render is applied to the Greenboard substrate at approximately 4-8mm in thickness which allows qualified applicators to screed out usual imperfections and form a seam free level 5 finish. NRG recommends render over Greenboard should be specified by a coating manufacturer.


  • NRG Greenboard is comprised of 98% air and therefore only 2% polystyrene making it a highly efficient use of raw material.
  • NRG Greenboard remains inert, is non toxic, odour free and non-biodegradable.
  • No CFC’s or HCFC’s foam agents are used in its manufacture, so NRG Greenboard causes no damage to the ozone layer.
  • Effective installation of NRG Greenboard can cut carbon dioxide emissions by up to 50%.
  • The R-value of NRG Greenboard does not deteriorate during its life time; therefore the reduction in emissions lasts the full lifetime of the building.
  • The energy used to manufacture NRG Greenboard is recovered within six months by the energy saved in the building in which NRG Greenboard is installed.
  • Typically, for every kg of oil used in NRG Greenboard manufacturing, about 200kg will be saved in reduced heating demands.
  • All NRG Greenboard waste is recycled. Either through installation of off-cuts in the wall cavity or it can be granulated and mixed with virgin material to make new products.

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AWTA Product Test Fire


Material Specification provided by client:
Nominal composition: Expanded polystyrene foam
Nominal thickness: 75mm

AS/NZS 1530.3 – 1999
Simultaneous determination of Ignitability, Flame Propagation, Heat Release and Smoke Release.


These results only apply to the specimen mounted, as described in this report. The results of this fire test may be used to directly assess fire hazard, but it should be recognized that a single test method will not provide a full assessment of fire hazard under all fire conditions. Each test specimen had an unattached backing of 4.5mm thick fibre reinforced cement board.

Each test specimen was restrained on the exposed face by a layer of galvanised welded square mesh made from wire of nominal diameter 0.8mm and nominal spacing 12mm in both directions and the assembly clamped in four places.

The specimens melted and flowed away from the area of maximum heat during the test. Due to this phenomena, it should be recognised that this test result may not be a true indication of the product’s fire hazard properties.

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Laboratory Acoustical Testing

Laboratory Acoustical Testing of Wall System containing Expanded Polystyrene Foam

Test Objectives:

Measurement of airborne Sound Reduction Indices ( R ) of sample wall system in accordance with AS1191-2002 Acoustics – Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Elements.

Determination of Weighted Sound Reduction Indices ( R w ) and Spectrum Adaption Terms (C tr) in accordance with AS/NZS ISO 717.1.2004: Acoustics – Rating of sound insulation in buildings and of building elements – Airborne sound insulation.

Description of Test Specimens

Side 1: 6mm concrete render applied to 60mm thick expanded polystyrene foam. The polystyrene applied with sheet lengths vertical. Framing: 90mm timber studs at 450mm centres
Side 2: 10mm Plasterboard applied with sheet lengths vertical. Joints no set, some visible gaps up to 8mm wide. Edges caulked with expanding polyurethane foam.

Description of Test Facilities:

The tests were carried out in a purpose-designed transmission loss suite, comprising two adjoining reverberant rooms, designed in accordance with AS1191-1985.

Room construction:

solid concrete; independent construction for source and receiving rooms with separate foundations.

Room shape:

Rectangular parallel piped for both rooms; aspect ratios 1.6:1.3:1 for both rooms.

Room Volume:

Source room 100m3; receiving room 170m3 Average Absorption coefficient: less than 0.06 at all frequencies.


Receiving room diffuser area 30.7m2 compared with largest surface (floor/ceiling) of 40m2;ratio 0.75.

Test Aperture:

3.16m x 3.16m (Nom). In this instance, craft wood jamb linings were fitted to the test aperture. These reduced the effective aperture area to 9.98m2.


  • Precision sound level meter, Rion NA-27 (S/N 00380650).
  • Acoustical calibrator, Bruel & Kjaer type 4231 S/N 1897734.
  • Sound source, custom made pink noise generator, 150W power amplifier and a stereo two-way loudspeaker system.

Test Procedures: Sound Source and Location

Broad band pink noise located in the rear trihedral corners of the source room.

Space and time average:

  • Continuous moving path
  • Repeated three times
  • Path length approx 15m
  • Averaging time 120 sec.

Equivalent Absorption:

Was determined by reverberation time measurement using the built-in software with the Rion NA-27 sound level meter. The sound source was used to excite the room. Two source locations were used each with tree microphone locations to comply with the Code.

Measurements Precision:

Each measurement was repeated three times. Repeatability was better than 1dB in every frequency band.

Test Results:

The test results are appended with a summary provided in Table 1 and complete 1/3 Octave data provided in Table 2.

Weighted Sound Reduction Index (rw)

6mm Render, 60mm ESP on 90mm timber studs at 450mm centres, with 10mm plasterboard (Plasterboard joints no set, edges caulked with expandable polyurethane foam)

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Thermal Resistance of an Insulation Sample


NRG Building Systems Pty Ltd, 30 Binary Street, Yatala, QLD 4207, Australia


The test equipment used was a Laser Comp Fox 600 heat flow meter. The specimen for testing is placed horizontally in the apparatus, with upwards heat flow. The hot and cold plates each have a 250 mm x 250 mm heat flux transducer embedded in their surface. The edges of the specimen are insulated from the room ambient temperature.


The specimen was supplied by the client and consisted of one piece of light green polystyrene. The dimensions of the sample were 595 x 595 mm. It was tested at its actual thickness, to the requirements of ASTM C518-04.


These measurements comply with the requirements of ASTM C518. The uncertainty in the measurements of thermal conductivity and thermal resistance are estimated to be ± 3%.

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