Kingspan Kooltherm K10 PLUS Soffit Board Insulation

Kingspan Kooltherm K10 PLUS Soffit Board, render of a board showing the grey fibre cement face and pink phenolic core

1/2

Kingspan Kooltherm K10 PLUS Soffit Board Insulation

$2,961.00

GST inclusive

Opening Offer: 5% off orders over $1,000, 7% over $2,500, 10% over $4,000. Ends 30 November. Offer details

Thickness and edge

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

Kingspan Kooltherm K10 PLUS Soffit Board is a phenolic insulation board with a 6 mm fibre cement sheet bonded to its face, for the underside of concrete roof and floor slabs. It runs from R1.10 at 31 mm to R3.70 at 86 mm, in 2400 x 1200 mm boards made in Australia.

Thickness and edge

Thickness includes the sheet, so the 31 mm board holds 25 mm of insulation. We list six thicknesses with a Villaboard face and recessed edges for flush jointing, and all seven with square edges for butt joins. Under a 150 mm roof slab with no ceiling, Kingspan's Total R-value rises from RT1.4 at 31 mm to RT3.8 heat flow in at 86 mm. Other slab thicknesses need their own calculation.

Fire figures

The board is NCC Group 1 to AS 5637.1:2015. Kingspan calls the fibre cement face non-combustible, not the whole board, and says its smoke development figure of 3 or less applies to the K10 core only.

Packs and lead time

Sold in Kingspan's full packs, from 12 boards (34.56 m²) at 31 mm to 4 boards (11.52 m²) at 86 mm. Every size is made to order and takes about 10 business days.

On site

Fix each board with at least 11 insulation fasteners with 25 mm or larger heads, or screw it to treated battens on an uneven slab. Keep boards dry, and never cover the face of a cast-in fire collar. For a foil underside, see the Kooltherm K10 G2 Soffit Board. Full figures are in the table below.

Technical data

Kingspan technical data sheet (PDF)

Kingspan · Rigid thermoset closed cell phenolic insulation, fibre-free core, with a 6 mm fibre cement sheet on the front face and a tissue based facing on the back · Insulated fibre cement sheet for concrete soffits: the underside of a concrete roof slab with no ceiling, or of a concrete floor over an unenclosed sub-floor application

Sizes stocked

Thickness	Product R-value	Edge	Boards per pack	m² per pack	Product code	Supply
31 mm	R1.10	Recessed, Villaboard face	12	34.56 m²	100000047820	Made to order, about 10 business days
31 mm	R1.10	Square	12	34.56 m²	100000037889	Made to order, about 10 business days
36 mm	R1.40	Recessed, Villaboard face	10	28.8 m²	100000073893	Made to order, about 10 business days
36 mm	R1.40	Square	10	28.8 m²	100000037890	Made to order, about 10 business days
46 mm	R1.75	Recessed, Villaboard face	8	23.04 m²	100000048098	Made to order, about 10 business days
46 mm	R1.75	Square	8	23.04 m²	100000037824	Made to order, about 10 business days
56 mm	R2.30	Recessed, Villaboard face	6	17.28 m²	100000038585	Made to order, about 10 business days
56 mm	R2.30	Square	6	17.28 m²	100000038336	Made to order, about 10 business days
66 mm	R2.75	Recessed, Villaboard face	5	14.4 m²	100000049898	Made to order, about 10 business days
66 mm	R2.75	Square	5	14.4 m²	100000037497	Made to order, about 10 business days
76 mm	R3.25	Square	4	11.52 m²	100000038742	Made to order, about 10 business days
86 mm	R3.70	Recessed, Villaboard face	4	11.52 m²	100000036746	Made to order, about 10 business days
86 mm	R3.70	Square	4	11.52 m²	100000043450	Made to order, about 10 business days

Board

Board size	2400 x 1200 mm (2.88 m²)
Thickness quoted	Total thickness, including the 6 mm fibre cement sheet
Insulation inside each thickness	31 mm: 25 mm, 36 mm: 30 mm, 46 mm: 40 mm, 56 mm: 50 mm, 66 mm: 60 mm, 76 mm: 70 mm, 86 mm: 80 mm
Fibre cement sheet	6 mm nominal
Edge options	Recessed edges with a Villaboard face, or square edges

A recessed edge is made for flush jointing and a square edge for butt joins.

Thermal

R-value basis	Declared product R-value at 23 °C
Thermal conductivity, insulant 25 to 44 mm	0.023 W/m.K at 23 °C
Thermal conductivity, insulant 45 mm and over	0.022 W/m.K at 23 °C
Thermal conductivity, fibre cement sheet	0.23 W/m.K at 23 °C (6 mm sheet)

The product R-value is for the board alone, while the Total R-values below cover the whole slab build-up.

Total R-value, concrete roof slab with no ceiling (150 mm concrete)

31 mm	RT1.4 heat flow in, RT1.4 heat flow out
36 mm	RT1.6 heat flow in, RT1.6 heat flow out
46 mm	RT2.0 heat flow in, RT2.1 heat flow out
56 mm	RT2.5 heat flow in, RT2.6 heat flow out
66 mm	RT3.0 heat flow in, RT3.1 heat flow out
76 mm	RT3.4 heat flow in, RT3.5 heat flow out
86 mm	RT3.8 heat flow in, RT4.0 heat flow out

A slab of any other thickness needs its own calculation.

Total R-value, unenclosed sub-floor (150 mm concrete)

31 mm	RT1.3 heat flow in, RT1.4 heat flow out
36 mm	RT1.5 heat flow in, RT1.7 heat flow out
46 mm	RT2.0 heat flow in, RT2.1 heat flow out
56 mm	RT2.5 heat flow in, RT2.7 heat flow out
66 mm	RT2.9 heat flow in, RT3.1 heat flow out
76 mm	RT3.3 heat flow in, RT3.6 heat flow out
86 mm	RT3.8 heat flow in, RT4.0 heat flow out

Fire

NCC fire classification (AS 5637.1:2015 / AS ISO 9705:2003 (R2016))	Group 1
Outer face	Non-combustible building board (the fibre cement sheet)
Spread of Flame Index (AS 1530.3:1999)	0
Smoke Development (AS 1530.3:1999)	≤ 3, applies only to the K10 insulation board used in the product
Average specific extinction area (AS/NZS 3837:1998)	≤ 100 m²/kg, applies to compliant fibre cement facing

Kingspan calls the fibre cement face non-combustible, not the whole board.

Vapour and strength

Water vapour	Resistant to the passage of water vapour
Water vapour transmission (ASTM E96 Part B-2016)	> 35 MN·s/g
Fibre cement sheet resistivity, for condensation risk calculations	250 MN·s/g·m
Compressive stress of insulant (AS 2498.3:1993)	On average exceeds 100 kPa at 10% compression

Kingspan suggests sealing the joints where vapour transmission needs to be kept down.

Material and handling

Core	Rigid thermoset, closed cell phenolic insulation, fibre-free
Facings	Fibre cement sheet on the front, tissue based facing on the back, autohesively bonded during manufacture
Made in	Australia
Insulation board plant	Somerton, Victoria
Packaging	Packs, labelled and shrink-wrapped in polythene
Storage	Ideally inside a building. The packaging is not adequate for long term outdoor protection
Wet or damaged boards	Do not use boards that have got wet, are damaged, or have been in contact with harsh solvents or acids
Adhesives	The core is not resistant to some solvent-based adhesives, particularly those containing methyl ethyl ketone
Safety	Chemically inert. A Product Safety Information sheet is available from Kingspan

Compliance and warranty

Product standard	NCC and AS/NZS 4859.1:2018 compliant
Total R-value calculation	NCC 2022 energy provisions, AS/NZS 4859.2:2018 and NZS 4214:2006
Buildings covered by the Total R-value tables	NCC Volume One Class 2 to 9, NCC Volume Two Class 1 and 10a
Installation standards	AS 2908.2:2000 (fibre cement sheet), AS 3999:2015 (bulk thermal insulation), AS 3000:2018 (wiring)
Management systems	ISO 9001:2015, ISO 14001:2015, ISO 45001:2018, ISO 50001:2018, ISO 37301:2021
Warranty	10 years, residential and commercial, subject to Kingspan's full Kooltherm warranty terms
Project warranty	Kingspan's specification clause asks for a Kingspan Project Specific Warranty to be submitted
GreenTag	Global GreenTag GreenRate Level A, licence KIN:VI05:2025:GR, valid to 23 January 2027
Environmental Product Declaration	EPD S-P-07446, valid until 23 March 2028

Fitting notes

Install the fibre cement sheet to AS 2908.2:2000 and the insulation to AS 3999:2015, with any wiring work to AS 3000:2018. Fixed straight to the concrete, each 2400 x 1200 board takes at least 11 insulation fasteners with a head diameter of at least 25 mm, which is 3.81 fixings per m². Put four along each long edge, 50 to 150 mm in from the edge, and three down the middle, spread evenly. Joints can be staggered or squared. The fixing must suit the application, exposure and fire rating, and where the board sees wind pressure, extra fixings are assessed to the Australian wind load standards. On an uneven slab or around services, fix treated 50 x 25 mm battens or furring channels at 600 mm centres to suit the board edges and centres, then screw the boards to them at no more than 300 mm, in rows no more than 600 mm apart, at least 12 mm from sheet edges and 50 mm from corners. Fit the board tight to fire collars but never cover the exposed face of a cast-in collar. Cut with a fibre cement blade and trim for close-butting joints. Kingspan says taping is not required for bonded boards, though sealing the joints cuts vapour transmission. Protect exposed edges with silver Kingspan Insulation Tape lapped at least 48 mm onto the face, or a metal C-section. Store the packs inside. If they have to sit outdoors, stack them off the ground under an opaque polythene sheet or tarpaulin, and do not use any board that has got wet.

Figures are taken from the Kingspan Kooltherm K10 PLUS Soffit Board product data sheet, KIAU0059 Issue 13, November 2024. Edge types, boards per pack, product codes and lead time are from Kingspan's current Kooltherm product list (May 2026), and the GreenTag and EPD details from Kingspan's GreenTag certificate KIN:VI05:2025:GR and EPD S-P-07446. The manufacturer document is linked above. Kingspan can change specifications without notice, so check the current sheet before specifying on a job.

Common questions

Why is the thinnest board 31 mm and not 25 mm?

Kingspan quotes the product thickness with the 6 mm fibre cement sheet included. The 31 mm board is 25 mm of insulation plus the sheet, and the R-values are declared against the total thickness.

What is the difference between the recessed edge and square edge boards?

Kingspan's list offers each thickness with a Villaboard face and recessed edges or with square edges, at the same R-value. Recessed edges are made for flush jointing and square edges for butt joins. We list the 76 mm board with square edges only.

What Total R-value do I get under a 150 mm slab?

Under a roof slab with no ceiling, Kingspan gives RT1.4 both ways at 31 mm, up to RT3.8 heat flow in and RT4.0 heat flow out at 86 mm. Over an unenclosed sub-floor it is RT1.3 in and RT1.4 out at 31 mm, up to RT3.8 in and RT4.0 out at 86 mm. Other slab thicknesses need their own calculation.

Is K10 PLUS non-combustible?

Kingspan calls the fibre cement outer face a non-combustible building board, not the whole product. The board has an NCC Group 1 fire classification to AS 5637.1:2015. Its AS 1530.3 results are a spread of flame index of 0 and smoke development of 3 or less, and Kingspan footnotes the smoke figure as applying only to the K10 insulation board inside it.

How many fixings does each board need?

At least 11 insulation fasteners per 2400 x 1200 board, each with a head of at least 25 mm, which works out at 3.81 per m². Four go along each long edge, 50 to 150 mm in from the edge, and three down the middle. Where wind pressure acts on the board, extra fixings are assessed to the Australian wind load standards.

How much does a pack cover, and how long does it take?

Each board is 2.88 m². A pack is 12 boards (34.56 m²) at 31 mm, 10 (28.8 m²) at 36 mm, 8 (23.04 m²) at 46 mm, 6 (17.28 m²) at 56 mm, 5 (14.4 m²) at 66 mm and 4 (11.52 m²) at 76 and 86 mm. Every size is made to order and takes about 10 business days.

Can the packs be stored outside?

Ideally not. Kingspan says the pack wrapping is not adequate for long term outdoor protection. If outdoor storage cannot be avoided, stack the boards off the ground under an opaque polythene sheet or tarpaulin, and do not use any board that has got wet.

What about fire collars in the slab?

Fit the board tight to the collar to cut thermal bridging through the slab, but never cover the exposed face of a cast-in fire collar.

Cannot see your question? Ask our team and we will get you an answer.

Answers use the Kingspan Kooltherm K10 PLUS Soffit Board product data sheet, KIAU0059 Issue 13 (November 2024), and Kingspan's current Kooltherm product list (May 2026) for edge types, pack contents and lead time.