New Kooltherm K10 G2 Soffit Board

Product Code


Insulation for Concrete Soffits

Kingspan Kooltherm K10 G2 Soffit Board is a super high performance, fibre-free rigid thermoset phenolic insulation core, sandwiched between an upper tissue-based facing and a lower facing of highly reflective aluminium foil autohesively bonded to the insulation core during manufacture.

Kingspan Kooltherm K10 G2 Soffit Board is manufactured without the use of CFCs/HCFCs and has zero Ozone Depletion Potential (ODP) and low Global Warming Potential (GWP).

  • Group 2 NCC fire classification
  • Fibre-free, closed cell insulation core
  • NCC and AS/NZS 4859.1:2018 compliant

Product Data
Declared Thermal Conductivity (λ-Value) 0.021 W/m.K at 23oC (Insulant Thickness ≥ 45 mm)
0.023 W/m.K at 23oC (Insulant Thickness 25 – 44 mm)
Emittance (Foil Face) E0.05
Product Dimensions 2400 mm x 1200 mm (2.88 m2)
Nominal Product Thickness 25, 30, 40, 50, 60, 70, 80, 90 mm

Technical Service

If your construction is different from those specified, and/or to gain a comprehensive R-value calculation and technical information of your project, please consult the Kingspan Insulation Technical Service Department for assistance. Call 1300 247 235 and press “2” to speak with Technical services, email, or use the online contact form.

Assumption and Key

NCC 2019 prescribes different methods to determine Total R-value Calculations for Volume 1 and Volume 2. The systems noted on this page are Total R-values for the building element as required by the Energy Provisions of the National Construction Code, calculated in accordance with AS/NZS 4859.2 2018 & NZS 4214. Kingspan Kooltherm® products are manufactured, tested and packaged in conformance with AS/NZS 4859.1:2018

Product R-values

Product Thickness Product R-value
25 mm R1.10
30 mm R1.30
40 mm R1.75
45 mm R2.15
50 mm R2.35
60 mm R2.85
70 mm R3.35
80 mm R3.80
90 mm R4.30
100 mm R4.75

Concrete Roof (Soffit) – No Suspended Ceiling

System R-value
Total R–values for various thicknesses of Kingspan Kooltherm® K10 G2 Soffit Board Applicable for NCC Volume One, Class 2 to 9 buildings & NCC Volume Two, Class 1 & 10a buildings, & NCC Volume One, Class 2 sole-occupancy unit or a Class 4 part of a building.

Insulation Thickness Heat Flow In (Summer) Heat Flow Out (Winter)
25 mm RT2.0 RT1.5
30 mm RT2.2 RT1.7
40 mm RT2.6 RT2.2
45 mm RT3.0 RT2.6
50 mm RT3.2 RT2.8
60 mm RT3.7 RT3.3
70 mm RT4.2 RT3.8
80 mm RT4.6 RT4.3
90 mm RT5.1 RT4.8

Concrete thickness: 150 mm

Roof application, suspended ceiling void greater than 300mm

System R-value

Insulation Thickness Heat Flow In (Summer) Heat Flow Out (Winter)
25 mm RT2.5 RT2.0
30 mm RT2.7 RT2.2
40 mm RT3.1 RT2.7
45 mm RT3.5 RT3.1
50 mm RT3.7 RT3.3
60 mm RT4.2 RT3.8
70 mm RT4.7 RT4.3
80 mm RT5.1 RT4.8
90 mm RT5.6 RT5.3

Concrete thickness: 150 mm

Concrete Floor (Soffit) – Unenclosed Sub-Floor

System R-value
Total R–values for various thicknesses of Kingspan Kooltherm® K10 G2 Soffit Board Applicable for NCC Volume One, Class 2 to 9 buildings & NCC Volume Two, Class 1 & 10a buildings, & NCC Volume One, Class 2 sole-occupancy unit or a Class 4 part of a building

Insulation Thickness Heat Flow In (Summer) Heat Flow Out (Winter)
25 mm RT1.3 RT1.4
30 mm RT1.5 RT1.6
40 mm RT1.9 RT2.1
45 mm RT2.3 RT2.5
50 mm RT2.5 RT2.7
60 mm RT3.0 RT3.2
70 mm RT3.5 RT3.7
80 mm RT3.9 RT4.2
90 mm RT4.4 RT4.7

Concrete thickness: 150 mm

Concrete Floor (Soffit) – Enclosed Sub-Floor

System R-value

Insulation Thickness Heat Flow In (Summer) Heat Flow Out (Winter)
25 mm RT2.0 RT2.7
30 mm RT2.3 RT3.0
40 mm RT2.7 RT3.4
45 mm RT3.1 RT3.8
50 mm RT3.3 RT4.1
60 mm RT3.8 RT4.5
70 mm RT4.2 RT5.0
80 mm RT4.7 RT5.5
90 mm RT5.1 RT6.0

Concrete thickness: 150 mm

Kooltherm K10 G2 Soffit Board Model Specification
You can also download the comprehensive model specification here.

Specification Clause

The soffit insulation shall be Kingspan Kooltherm® K10 G2 Soffit Board ___ mm thick, Group 2, with a tested SMOGRARC of not more than 30 m2/s2 x 1000, comprising a CFC/HCFC-free and zero Ozone Depletion Potential (ODP) rigid thermoset phenolic insulation core with an upper tissue-based facing and a lower facing of highly reflective aluminium foil, manufactured under a management system certified to ISO 9001:2015, ISO 14001:2015, OHSAS 18001:2007 and ISO 50001:2011 by Kingspan Insulation Pty Ltd and shall be installed in accordance with the instructions issued by them. A Project Specific Warranty provided by Kingspan Insulation must be submitted.

Specify with:

Handling & Storage

The packaging of Kingspan Kooltherm should not be considered adequate for long term outdoor protection. Ideally boards should be stored inside a building. If, however, temporary outdoor storage cannot be avoided then the boards should be stacked flat on a level base, clear of the ground, and completely protected from inclement weather through use of a polythene sheet or weatherproof tarpaulin. Boards that have been allowed to get wet should not be used.

Resistance to Solvents
The insulation core is resistant to short-term contact with petrol and with most dilute acids, alkalis and mineral oils. However, it is recommended that any spills be cleaned off fully before the boards are installed. Ensure that safe methods of cleaning are used, as recommended by suppliers of the spilt liquid. The insulation core is not resistant to some solvent-based adhesive systems, particularly those containing methyl ethyl ketone. Adhesives containing such solvents should not be used in association with this product. Damaged boards or boards that have been in contact with harsh solvents or acids should not be used.

Kingspan Insulation products are chemically inert and safe to use. A Product Safety Information Sheet is available from Kingspan Insulation Pty Ltd.

Please note that the reflective surfaces on this product are designed to enhance their thermal performance. As such, the will reflect light as well as heat, including ultraviolet light. Therefore, if these boards are being installed during bright or sunny weather, it is advisable to wear UV protective sunglasses or goggles and if the skin is exposed for a significant period of time, protect bare skin with a UV block sun cream.

Foil facings are conductive to electricity – avoid contact with un-insulated electrical cables and fittings.

Installation must be in accordance with AS 3999 Bulk Thermal Insulation Installation and AS 3000 Electrical Installations (Wiring Rules).

Cutting and Taping

Cutting should be carried out either by using a fine toothed saw, or by scoring with a sharp knife, snapping the board over a straight edge and then cutting the facing on the other side. Ensure accurate trimming to achieve close-butting joints and continuity of insulation.

For all fixing methods board joints should be taped with a minimum 96 mm wide foil tape.

  • Firstly, ensure that the climate conditions are suitable for the tape being used as well as the product the tape is to be applied too.
  • The surface of the Kingspan Kooltherm to which aluminium foil tape is being applied, should be free of dust, dirt or oils. In any case, the surface should be cleaned with a dry cloth before application of the tape.
  • The release liner on the tape should be removed 300 – 600 mm at a time and the adhesive face pressed firmly onto the insulation facing. Care should be taken not to stretch the tape tightly as this will create buckles and voids in the contact area.
  • Care must also be taken to apply the tape over the centre of the join so that there is adequate area on both sides of the joint for the tape to bond. Uneven width distribution also puts additional shear stress on the smaller side of the butt joint.
  • The tape should then be wiped firmly from the centre out (like wallpaper) with a plastic squeegee. The more pressure that is applied, the more surface contact will be reached, therefore, the greater the bond surface.
  • The tape should then be cut and fitted with a knife and scissors. The same wiping instructions should then be used as above.

In the absence of other protection exposed board edges should be protected by silver Kingspan Insulation Tape with a minimum 48 mm wide overlap onto the board face or alternatively use a  proprietary metal c-section.

Where the board edge is exposed at the external building perimeter, appropriate protection should be detailed to shelter from adverse weather.

Concrete Soffit

Fixing Directly to Concrete Soffits
Kingspan Kooltherm K10 G2 Soffit Board can be fully restrained to a concrete soffit by the use of minimum 11 No. approved insulation fasteners with a minimum head diameter of 35 mm.

  • The fasteners should be evenly distributed over the whole areaof the board and designed to  provide suitable restraint for the project requirements. Consultation with the chosen fastener
    supplier is recommended.
  • Board joints can be either staggered (see Figure 5) or squared (see Figure 6) and taped with 96 mm wide silver Kingspan Insulation Tape. Fasteners along each length – no less than 50 mm – no more than 150 mm from edge of board, 3 No. fasteners along the middle (offset from edge positions as per diagram Figure 3).
  • Where the board may be subject to external wind pressure, the requirement for additional fixings should be assessed in accordance with appropriate Australian wind load standards.
  • Consideration should be given to the material the fixing is made from and should be deemed appropriate for application, exposure and fire rating by the fixing manufacturer.

About fixings, why 11 fixings?
Best practice determines that any rigid board insulation, not just Kingspan Kooltherm® K10 G2 Soffit Board, should be fixed with 11 appropriate fixings for very good reasons:

  • There will always be differential expansion and contraction between any rigid insulation material and adjacent building products due to varying moisture content and temperature.
  • In any concrete forming, there will be an uneven surface throughout the slab.
  • Where concrete formwork is joined it is normal to have ridges of up to 3 mm which make the concrete surface uneven.
  • An insulation board held horizontally may bow like any other sheetmaterial under its own weight.

Using 11 fixings ensures that the insulation board has a strong and permanent fix under the concrete soffit and that it is not compromised by any of the above issues. It also provides a proven robust fire safe solution.

These best practice recommendations are a result of over 30 years of Kingspan Insulation experience in soffit applications.

Proprietary Grid Systems

  • Kingspan Kooltherm® K10 G2 Soffit Board can also be fixed to a proprietary grid system comprising metal furring bars or timber battens. For further information regarding proprietary grid system specifications, please contact the Kingspan Insulation Technical Service Department.

For advice on ancillary materials, such as fixings and tapes please contact our Technical Services Department.

Installation around Fire Collars

  • Fitting Kingspan Kooltherm® K10 G2 Soffit Board tight to the fire collar is recommended to reduce the effects of thermal bridging through the slab.
  • Do not cover the face of the fire collar. For fire collars to activate in a fire situation the front face needs to be exposed. This is particularly important when using cast-in collars as the face will be flush with the concrete and it would be easy to cover with the insulation board.

CAD PDF – Flat Concrete Roof Soffit_No Suspended Ceiling Download
PSI – Kooltherm Range Download

Management Standards

Standard Management System
ISO 9001:2015 Quality Management
ISO 14001:2015 Environmental Management
ISO 45001:2018 Health and Safety Management
ISO 50001:2011 Energy Management

Product Testing

Characteristic Standard Result
Compressive Stress AS 2498.3 Typically exceeds 100 kPa at 10% compression
Water Vapour Resistance BS EN 12086:1997 / I.S. EN 12086:1998 > 35 MN·s/g

Fire Performance

Test Test Method Result
Flame Spread
Heat Release
Smoke Release
AS 1530.3 Spread of Flame Index: 0
Smoke Development ≤ 3
NCC Group Number AS ISO 9705 Group 2
Tested in accordance with AS/NZS 5637 as required by NCC
FM Class No. 4880* UBC 26-3 Class 1
SMOGRARC AS ISO 9705 ≤ 30 m2/S2x1000
Fire-resistance test of elements of construction AS 1530.4** -/240/240 (HDPE pipe)

*This approval is valid for ceiling / soffit installation only, with non-combustible walls. Please contact us for correct installation instructions.
** Testing to AS 1530.4 performed in accordance with NCC BCA C3.15 Opening for service penetrations using a 120 mm concrete soffit.

Environmental Data Table

Aspect Characteristic
Recyclability Non-contaminated insulation site waste is recyclable, but there are currently no facilities in Australia to process returned material
Re-usability Re-usable if removed with care (long term of service expected)
Water Use No water used in Kingspan Insulation’s manufacturing process
Blowing Agent Global Warming Potential (GWP) Manufactured with a blowing agent that has low GWP
Blowing Agent Ozone Depletion Potential (ODP) Manufactured with a CFC/HCFC-free blowing agent that has zero ODP
Packaging Contains 0% recycled product
Polythene wrap and EPS skids 100% recyclable

FM Certification
The Factory Mutual Approval standard for soffit lining boards is Class Number 4880:2015 (Approval Standard for Class 1 Fire Rating of Building Panels or Interior Finish Materials). Kingspan Kooltherm® K10 G2 Soffit Board (thicknesses up to, and including, 120 mm) produced at Kingspan Insulation’s Somerton manufacturing facility is certified as achieving Class 1 Fire Rating to Factory Mutual Class Number 4880.

For further details please contact the Kingspan Insulation Technical Service Department or alternatively search for Kingspan Insulation on

This approval is valid for ceiling / soffit insulation only, with non–combustible walls with no height restriction. This approval is valid for any fixing specification. However, for mechanical reasons, the fixing specification and the taping specification must still be followed.