Kingspan Kooltherm K8 Cavity Board Insulation
25mm - R1.10 (20 boards per pack, 12.34 m²)
$535.00
Sale price
$535.00
Regular price
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Kingspan Kooltherm K8 Cavity Board Insulation
$535.00
Sale price
$535.00
Regular price
GST inclusive
Opening Offer: 5% off orders over $1,000, 7% over $2,500, 10% over $4,000. Ends 30 November. Offer details
How many do you need?
Measure the wall, ceiling or roof area and take about 10% off for studs, joists and purlins.
You need
Which covers
Total
Dispatch: Most orders are processed the same day. Metro delivery: Usually 1–3 business days. We do our best to get most items out on the next business day.
Delivery to VIC and NSW: $55 in metro Melbourne and metro Sydney, $99 in the outer ring around both cities, $149 anywhere else in the two states · Local pickup from Epping, VIC by arrangement · Shipping details
Kooltherm K8 Cavity Board is Kingspan's insulation board for masonry cavity walls: a fibre-free, closed cell phenolic core faced on both sides with reflective composite foil. It fixes to the inner leaf on the wall ties and leaves a clear cavity to the outer leaf. Made in Australia in 25 mm (R1.10) and 40 mm (R1.75).
Choosing the thickness
Kingspan publish wall totals with a 40 mm airspace. In double brick, 25 mm gives RT2.2 heat flow in and RT2.3 out, and 40 mm gives RT2.9 both ways. On a 190 mm corefilled block inner leaf the totals are RT2.2 both ways at 25 mm, and RT2.8 in, RT2.9 out at 40 mm. For brick veneer or a timber or steel frame, look at Kooltherm K12 Framing Board.
Cavity width and fire limits
Kingspan require a residual cavity of at least 40 mm (AS 3700:2011, NCC Volume One B1D4), so the gap between the leaves has to take the board as well. Both example walls suit NCC Class 1 and 10a housing and Type C fire-resisting walls in Class 2 to 9 buildings. Type A and B walls in those buildings need a Performance Solution.
Packs and site notes
Boards are 1200 x 514 mm, sold in Kingspan's full packs: 20 boards (12.34 m²) at 25 mm, 12 boards (7.40 m²) at 40 mm. Both thicknesses are stocked. The foil conducts electricity and reflects UV, so keep it off bare cables and wear UV protective glasses in bright sun. Full figures are in the table below.
Technical data
Kingspan technical data sheet (PDF)Sizes stocked
| Nominal thickness | Declared R-value at 23 °C | Board size | Boards per pack | m² per pack | Product code | Supply |
|---|---|---|---|---|---|---|
| 25 mm | R1.10 | 1200 x 514 mm | 20 | 12.34 m² | 100000065190 | Stocked |
| 40 mm | R1.75 | 1200 x 514 mm | 12 | 7.40 m² | 100000065144 | Stocked |
Thermal
| Declared thermal conductivity, 25 to 44 mm insulant | 0.023 W/m·K at 23 °C (AS/NZS 4859.1:2018 / ASTM C518-2017) |
|---|---|
| Emittance, foil face | E0.06 (ASTM C1371:2015) |
The reflective foil faces improve the thermal resistance of the cavity next to the board.
Total R-values, typical walls with a 40 mm airspace
| Double brick cavity wall, 25 mm | RT2.2 heat flow in, RT2.3 heat flow out |
|---|---|
| Double brick cavity wall, 40 mm | RT2.9 heat flow in, RT2.9 heat flow out |
| Brick / block cavity wall (190 mm corefilled block inner leaf), 25 mm | RT2.2 heat flow in, RT2.2 heat flow out |
| Brick / block cavity wall (190 mm corefilled block inner leaf), 40 mm | RT2.8 heat flow in, RT2.9 heat flow out |
| Heat flow direction | Heat flow in is the summer case, heat flow out the winter case |
| Basis | Total R-values for the building element under the NCC 2022 Energy Provisions, calculated to AS/NZS 4859.2:2018 |
These are totals for the two walls Kingspan show, not for the board on its own.
Fire
| Early fire hazard (AS 1530.3:1999) | Spread of Flame Index 0, Smoke Development ≤ 3 |
|---|---|
| Smoke obscuration (Kingspan specification) | Tested at not more than 100 m²/kg |
| Fire-resisting construction | Typical walls shown suit NCC Class 1 and 10a housing and Type C walls in Class 2 to 9 buildings. Type A and B walls in Class 2 to 9 buildings need a Performance Solution. |
Talk to Kingspan Technical Services before using it in a Type A or B wall.
Moisture
| Residual cavity | At least 40 mm (AS 3700:2011, NCC Volume One B1D4) |
|---|---|
| Cavity | Clear cavity is maintained, resists moisture penetration |
| Water vapour transmission (ASTM E96 Part B-2016) | > 35 MN.s/g |
Material and handling
| Compressive stress (AS 2498.3:1993) | Typically exceeds 100 kPa at 10% compression |
|---|---|
| Blowing agent | Zero ODP and low GWP |
| Made in | Australia |
| Board area | 0.6168 m² (1200 x 514 mm; Kingspan's sheet gives this as 0.61 m²) |
| Packaging | Labelled packs, shrink-wrapped in polythene |
| Storage | Ideally inside a building. Outdoors, stack clear of the ground under an opaque polythene sheet or weatherproof tarpaulin. Do not use boards that have got wet. |
| Solvents | The core is not resistant to some solvent-based adhesives, particularly those containing methyl ethyl ketone |
| Electrical | Foil facings conduct electricity |
Pack coverage in the sizes table uses the exact board area.
Compliance
| Standards | NCC and AS/NZS 4859.1:2018 compliant |
|---|---|
| Management systems | ISO 9001:2015, ISO 14001:2015, ISO 45001:2018, ISO 50001:2018 |
| Environmental Product Declaration | EPD-IES-0014113:002, valid until 12 December 2029 |
| Warranty | 10 years for residential and commercial installations, subject to the Kingspan Kooltherm warranty terms (KIAU0190) |
The warranty covers manufacturing defects from installation and needs the boards stored, handled and installed to Kingspan's instructions.
Fitting notes
Install to AS 3999:2015 Section 4 and AS 3000:2018. Build the inner leaf to a working height and clean excess mortar and droppings off the edges of boards already in place. Place each board against the outer face of the inner leaf and hold it with a retaining disc or clip on every wall tie; wall tie type and spacing follow the NCC. Butt boards tightly to each other and around penetrations so there are no gaps. Leave 100 mm clear around heat producing electrical fittings and 50 mm around hot flues. Build the outer leaf up to the top of the boards, then repeat, keeping a residual cavity of at least 40 mm. Cut with a fine toothed saw, or score with a sharp knife, snap over a straight edge and cut the facing on the other side. The foil conducts electricity and reflects UV, so keep it away from bare cables and fittings and wear UV protective glasses in bright sun.
Figures are taken from the Kingspan data sheet for Kooltherm K8 Cavity Board, KIAU0051 Issue 19, December 2025, with the EPD (EPD-IES-0014113:002) and the Kooltherm product warranty (KIAU0190). Boards per pack follow Kingspan's pack quantities. The manufacturer document is linked above. Kingspan can change specifications without notice, so check the current sheet before specifying on a job.
Common questions
How wide does the cavity need to be?
Kingspan require a residual cavity of at least 40 mm, under the moisture provisions of AS 3700:2011 as called up in NCC Volume One B1D4. The gap between the leaves has to take the board plus that 40 mm.
What R-value does the wall actually get?
The board alone is R1.10 at 25 mm and R1.75 at 40 mm. In Kingspan's double brick wall with a 40 mm airspace the totals are RT2.2 in and RT2.3 out at 25 mm, and RT2.9 both ways at 40 mm. With a 190 mm corefilled block inner leaf they are RT2.2 both ways at 25 mm, and RT2.8 in and RT2.9 out at 40 mm.
How much wall does a pack cover?
Each board is 1200 x 514 mm. A 25 mm pack holds 20 boards and covers 12.34 m². A 40 mm pack holds 12 boards and covers 7.40 m².
Can I use it in brick veneer or a framed wall?
The K8 data sheet covers double brick and brick / block cavity walls. For brick veneer and timber or steel framed walls, Kingspan's board is Kooltherm K12 Framing Board.
Can it go in a fire-resisting wall?
Kingspan's typical walls suit NCC Class 1 and 10a housing and Type C fire-resisting walls in Class 2 to 9 buildings. Type A and B walls in Class 2 to 9 buildings need a Performance Solution. Its AS 1530.3 result is Spread of Flame Index 0 and Smoke Development ≤ 3.
Which adhesives should I keep away from it?
Some solvent-based adhesives, particularly those containing methyl ethyl ketone, because the core is not resistant to them. Do not use boards that are damaged or have been in contact with harsh solvents or acids.
Can the boards be stored outside?
Not for long. Kingspan say the pack wrapping is not adequate long-term outdoor protection, so store them inside where possible, or stack them off the ground under an opaque sheet or tarpaulin. Boards that have got wet should not be used.
Cannot see your question? Ask our team and we will get you an answer.
Answers use the Kingspan data sheet for Kooltherm K8 Cavity Board, KIAU0051 Issue 19, December 2025, and Kingspan's pack quantities.
