A curtain wall batt is a stone wool batt packed into the gap between a floor slab edge and the back of the facade, so fire and smoke cannot run up that gap from one storey to the next. The Bradford product is 50 mm thick, cut 1200 x 120 mm, 18 to a pack. It carries no fire rating on its own. The tested system carries the rating.
In short
- The clearance behind a curtain wall stacks up into one cavity from ground to roof. Sealing it is what the batt is for.
- NCC C3D7 governs it, worded identically in NCC 2022 and NCC 2025. The 2019 equivalent is C2.6.
- The batt appears in one of the four Deemed-to-Satisfy options, C3D7(1)(c), as the non-combustible packing. The 60/60/60 belongs to the construction behind it.
- Bradford's batt is 50 mm stone wool, 1200 x 120 mm, 18 per pack, 21.6 lineal metres, code 125082, compressed at least 10 per cent.
- CSR no longer publishes a statement for it. The one document we reached dates from 2014 and names no test report.
The gap the batt fills
A curtain wall carries no building load. Bradford's glossary calls it the "Outside skin or shell of a building that is supported off each individual slab level." It hangs off every slab and sits clear of it, so stacked up the building that clearance becomes one cavity, ground to roof.
The glossary separates two things a specification runs together. Firesafing is "Rockwool mineral fibre installed to the cavity between the edge of the slab and the curtain wall frame. Its purpose is to impede fire and smoke." Spandrel insulation goes into the "Solid wall element below the window sill", a different element entirely.
The guide is blunt: "Many fires have been reported to have moved floor to floor directly through the gap between the floor slab and the curtain wall." A rated slab does little for the storey above if fire walks around its edge.
What C3D7 actually asks for
The clause is C3D7, Vertical separation of openings in external walls. We read the NCC 2022 and NCC 2025 pages side by side and the text is word for word identical. The 2019 equivalent is C2.6. Two conditions gate it.
The first is construction type. The clause is written for Type A construction, and the ABCB guidance notes it also reaches Class 9a buildings of Type B construction, because those are the other buildings required to fire separate between floors: C3D6 sends the openings bounding patient care areas to C3D7 "as if the building were of Type A construction". Which type applies is the surveyor's call. The second is geometry. The vertical projection of the upper opening must fall no further than 450 mm outside the lower one. C3D7(3) defines an opening as "that part of the external wall of a building that does not have an FRL of 60/60/60 or greater", so a glazed facade is an opening across its whole area.
| C3D7 option | What it is | The numbers | Where the batt fits |
|---|---|---|---|
| (1)(a) | A spandrel between the two openings | At least 900 mm high, at least 600 mm above the intervening floor, non-combustible, FRL 60/60/60 | Not involved |
| (1)(b) | Part of a curtain wall or panel wall doing the same | As (a) | Not involved |
| (1)(c) | Construction complying with (a) behind the curtain wall, with the gaps packed | As (a), plus packing that is non-combustible and withstands thermal expansion and structural movement without loss of seal against fire and smoke | This one. The batt is the packing. The 60/60/60 belongs to the construction behind it |
| (1)(d) | A horizontal projection off the face of the wall | At least 1100 mm outwards, at least 450 mm along the wall beyond the openings, non-combustible, FRL 60/60/60 | Not involved |
| (2)(c) | Sprinkler exemption | Specification 17 sprinklers throughout, other than FPAA101D or FPAA101H. C3D7(2) also exempts open deck carparks, open spectator stands and openings within one stairway | None of (1) applies at all |
Read (1)(c) slowly. The 60/60/60 attaches to the construction behind the facade, and the batt is only the material filling the gaps in it. The clause asks three things of that packing: non-combustible, able to survive thermal expansion and structural movement, and holding a seal against fire and smoke throughout. Compression answers the second. A steel flashing usually answers the third.
The batt, and its one document
We stock one item: Bradford Rockwool Fireseal Curtain Wall Batts, 50 mm thick, 1200 x 120 mm, 18 pieces to a pack, CSR code 125082. Eighteen pieces at 1.2 m gives 21.6 lineal metres, and lineal metres is how to estimate a long run of one joint.
The documentation is the reason this page exists. CSR Bradford no longer publishes a Product Technical Statement for it, and its sitemap carries no curtain wall page. The one manufacturer document we reached is a data sheet marked Fireseal Curtain Wall Batt V2, publish date 01/14, from an archived copy. It cites the combustibility standard as AS/NZS 1530.1:1994, the sheet's own slip for AS 1530.1-1994, and predates NCC 2019, 2022 and 2025.
The PDF linked from our own product page is the party wall batts statement, which does not cover code 125082, and the subtitle was copied from that product too. Both are being corrected. The four Fireseal products are compared in fire rated insulation batts.
| Property | Figure | Test or basis |
|---|---|---|
| Size and pack | 50 mm thick, 1200 x 120 mm, 18 per pack, 21.6 lineal metres, code 125082 | Manufacturer SKU table, matches our catalogue |
| Fusion temperature | In excess of 1150 °C | No test method stated |
| Thermal conductivity | 0.037 W/mK at 23 °C mean temperature | No test method stated |
| Declared R-value | None given | No AS/NZS 4859.1 figure in the document |
| Density | Not published | Absent from every source we read |
| Combustibility | Non-combustible | AS 1530.1-1994, printed on the sheet as AS/NZS 1530.1:1994 |
| Fire hazard indices | Ignitability 0, spread of flame 0, heat evolved 0, smoke developed 0 | AS/NZS 1530.3:1999 |
| Fire Protection Level | Slab 120 mm against 45: -/120/120. Against 90: -/120/120. Against 135: -/120/90 | No test report, assessment number or assessor named |
Two things need saying. That smoke developed index of 0 disagrees with the rest of the family, because every current Fireseal statement we hold gives 1 on the same standard, so quote it as the 2014 sheet's figure or not at all. And the Fire Protection Level table heads a column thickness of Fireseal Curtain Wall Batt with 45, 90 and 135, for a product supplied only at 50 mm. One, two or three batts compressed 10 per cent would give those figures, but the sheet never says so.
The blank density row is the one people ring about, because perimeter seals are usually specified denser than a ceiling batt. There is no figure to give. What Bradford publishes across the stone wool we carry runs from 50 kg/m³ for the Party Wall Sealer to 110 kg/m³ for Fibertex 820, and this batt sits somewhere in that band. We will not guess where. Those densities are listed in fire rated insulation batts and Fibertex and Fibermesh.
A second document circulates and describes something else. Bradford's Fire Protection Design Guide, drawings dated 2001, specifies a curtain wall batt at 1500 x 168 x 100 mm, compressed to 85 per cent of its original width, at a minimum effective depth of 135 mm. That is twice the thickness of the batt CSR sells now. Take concepts from that guide and never a number.
Compression is the fixing
The data sheet gives one installation instruction and repeats it in its sample specification: the batt "shall be compressed into position with a minimum 10 per cent compression in height, fitted snugly into the cavity." That is the retention mechanism. The batt is held by friction against both faces of the gap and nothing else, and no pins, clips or fixings are named anywhere in it. The design guide shows Fireseal support clips, but CSR no longer lists them.
Compression is also the second demand in C3D7(1)(c). A facade moves, so a gap that is 50 mm on the drawing is not 50 mm all day, and a batt cut to the exact width would open a crack the first time the joint grew. Bradford's reason for stone wool is its "remarkable resistance to shrinkage at temperatures encountered in fire conditions". The materials are compared in insulation materials compared.
What goes on top, and what we do not supply
The installation drawing shows four things at the slab edge: the concrete floor slab dimensioned 120 mm minimum, the batts compressed by a minimum of 10 per cent, a fire rated spandrel panel, and above the seal a layer labelled "Galvanised Sheet Steel (1.2mm tickness) Installed as smoke barrier", the manufacturer's spelling. That 120 mm is the slab, the figure heading the Min Depth of Slab column in the sheet's own Fire Protection Level table, not a facade dimension.
On whether that flashing is a condition of the rating the documents disagree. The 2014 table is silent. The design guide makes it compulsory: the fire safing "shall be installed in conjunction with a smoke seal of continuous galvanised steel sheeting at least 1.2mm thickness, sealed with a fire rated sealant between the back pan and the floor slab". The clause settles it, because C3D7(1)(c) asks for a seal against smoke as well as fire, and stone wool is an air permeable fibre.
None of that is ours. We searched our catalogue for spandrel board, safing, firestop, fire rated sealant and smoke flashing and stock none of it. We supply the batt. The rest comes from the facade or fire contractor, who installs the seal.
What the certifier will ask for
Nobody certifying a building asks to see a batt. They ask for the system: the detail drawing, the FRL claimed, the test report to AS 1530.4-2014 or the assessment standing in for it, and the assessor behind it. Service penetrations and control joints are covered by AS 4072.1-2005, referenced alongside AS 1530.4 at C4D15. A perimeter gap is neither, which is why the evidence has to come from the tested facade system.
For this product we cannot hand that over. The 2014 sheet claims up to two hours of fire protection and prints -/120/120 without naming a test report or assessor. The rest of the range is documented properly: the party wall batts statement cites Jensen Hughes assessment FAS210056, Warringtonfire assessment FAS210154 and CSR lab report R-20121, and the FZ roof batts statement cites four more. The curtain wall sheet cites nothing.
So the sequence on a live job is fixed. Check whether C3D7 applies, then let the fire engineer or facade consultant nominate the tested system, which names the packing, its depth, its compression and the flashing and sealant with it. Only then does anyone order a batt, and swapping it later means the test no longer describes what was built. Product properties against system ratings is the subject of fire performance in insulation, and the same argument on separating walls is in insulation in party walls and apartments.
We supply it, and we install batts, wall wrap and sarking
AWBM stocks the Bradford Fireseal curtain wall batt at Epping and quotes it by the pack or by the lineal metre off your perimeter. Send the detail drawing or the specification clause and we will confirm the size, the pack count and the CSR code against it, and tell you what documentation exists. The spandrel board, flashing, sealant and clips are not ours, and a perimeter fire seal is installed by the facade or fire contractor to the tested detail. Delivery is $55 in metro Melbourne and metro Sydney, $99 in the outer suburbs and $149 anywhere else in Victoria and New South Wales, set by postcode.
Or browse fire protection, Rockwool and commercial insulation.
Frequently asked questions
What are curtain wall batts?
Non-combustible stone wool batts packed into the gap between a floor slab edge and the back of a curtain wall facade, so fire and smoke cannot pass up that cavity. Drawings call the element firesafing, and a schedule saying curtain wall insulation may mean the spandrel panel instead. Bradford's is 50 mm thick, 1200 x 120 mm, 18 to a pack, code 125082.
Do curtain wall batts have a fire rating?
No. A batt is a material and a fire resistance level belongs to a tested system, so the rating attaches to the whole slab edge detail: the construction behind the facade, the packing, the flashing and the sealant. Bradford's sheet prints -/120/120 and -/120/90 against slab depths but names no test report or assessor.
What does NCC C3D7 require at the slab edge of a curtain wall?
C3D7 applies to Type A construction, and to Class 9a buildings of Type B construction, where an opening sits above another and the vertical projection of the upper one falls no further than 450 mm outside it. The curtain wall option is C3D7(1)(c): construction behind the facade that is non-combustible, at least 900 mm high and rated 60/60/60, with the gaps packed in non-combustible material that holds its seal against fire and smoke as the walling moves.
Does a sprinklered building still need a perimeter fire seal?
Not under C3D7. Clause C3D7(2)(c) exempts a building with a Specification 17 sprinkler system throughout, other than FPAA101D or FPAA101H, because sprinklers "should prevent the fire developing to the stage where it could spread to the floor above". A seal may still be drawn for another reason, so confirm with the fire engineer.
What size are Bradford Fireseal curtain wall batts and how many come in a pack?
One size is made: 50 mm thick, 1200 mm long by 120 mm wide, 18 pieces to a pack under CSR code 125082. That gives 21.6 lineal metres per pack, the figure to estimate from on a linear joint. The sheet's nominal coverage of 0.54 square metres does not reconcile with those dimensions, so we quote lineal metres.
How much are curtain wall batts compressed?
A minimum of 10 per cent compression in height, fitted snugly into the cavity. Compression is the only thing holding the batt in place, because the data sheet names no pins, clips or fixings. It also keeps the seal closed as the facade moves, which is what C3D7(1)(c) demands.
What density are curtain wall batts?
Bradford does not publish one. No density appears in the data sheet, the design guide, our catalogue data or any stockist page we could find. Published densities across the Bradford stone wool range run from 50 to 110 kg/m³, but this batt sits in that band unnamed. Ask us to get it from CSR before ordering.
Can party wall batts be used in the perimeter gap instead?
No. The Fireseal Party Wall Batt is a different product for a different element: 100 mm thick, 1200 x 168 mm, five to a pack, scoped by its technical statement to inter-tenancy walls in Class 1 buildings only. C3D7 reaches Type A construction and Class 9a buildings of Type B construction, neither of which is Class 1.
Sources
- CSR Bradford, Fireseal Curtain Wall Batt data sheet V2, publish date 01/14, from an archived copy, 23 September 2026. Every figure attributed to the 2014 sheet.
- NCC 2022 and NCC 2025 Volume One, clauses C3D6 and C3D7 with guidance, ncc.abcb.gov.au, read 23 September 2026 and word for word identical. The options, definitions, exemptions and the Class 9a Type B reach.
- NCC 2022 Volume One, Schedule 2 Referenced documents, read 23 September 2026. Titles, years and referencing clauses for AS 1530.1-1994, AS/NZS 1530.3-1999, AS 1530.4-2014 and AS 4072.1-2005.
- CSR Bradford, Rockwool Fireseal Party Wall Batts, PTS058, Issue H, read 23 September 2026. Party wall size, code 119161, 75 kg/m³, R2.80, the Class 1 scope and the assessment references. Wrongly linked from our product page.
- CSR Bradford, Rockwool Fireseal Party Wall Sealer, PTS059, Issue H, read 23 September 2026, for 50 kg/m³.
- CSR Bradford, Fireseal FZ Roof Batts, PTS063, Issue C, read 23 September 2026, for the assessment and report references.
- Bradford Fibertex 820 (PTS068 Issue J) and Fibermesh 450 and 650 (PTS069 Issue D), read 23 September 2026, for 110 kg/m³ and the smoke developed index of 1.
- CSR Bradford Insulation, Fire Protection Design Guide, BI105.BMS7323.0901, drawings dated 2001, from a third party reseller CDN, 23 September 2026. The glossary, the fire path and the smoke seal. Its 1500 x 168 x 100 mm batt, 135 mm depth and 85 per cent compression are superseded.
- AWBM product data: variant titles and custom.datasheet metafields, read 23 September 2026. Sizes and codes from the CSR Bradford price catalogue, 28 May 2026.
General product information, current at September 2026. It does not decide compliance for any building. Whether C3D7 applies, what sits behind the facade, which system is tested and what a certifier accepts are for the fire engineer, the facade consultant and the building surveyor, and the specification takes priority. Manufacturers change specifications, so confirm with CSR Bradford before you order.