Repair Systems — 04
Roof insulation systems — R4 ceiling batts
Technical product reference for R4.0 and R4.1 ceiling batt insulation systems. Covers product selection, AS/NZS 4859 classification, NCC minimum R-values by climate zone, glasswool vs polyester alternatives, and brand comparisons for Australian residential and Class 2 strata buildings.
What are R4 ceiling insulation batt systems?
R4 ceiling batts are bulk insulation batts installed between ceiling joists at the ceiling level of a building — not in the roof space under the tiles. The R-value (thermal resistance) measures the insulation's ability to resist heat flow — R4.0 is the NCC minimum for ceiling insulation in climate zones 4–6. Ceiling batts are installed horizontally, resting in the ceiling joist bays above the plasterboard ceiling lining. They are entirely separate from under-tile sarking systems (reflective foil or PIR board) which are installed in the roof space under the roof tiles.
Brand Equivalency
| Brand | R value | Material |
|---|---|---|
| Bradford Gold | R4.1 | Glasswool |
| Bradford Polymax | R4.0 | Polyester |
| Knauf Earthwool | R4.0 | Glasswool |
| Fletcher Optimo | R4.0 | Glasswool |
Product Reference
4 products — 3 brands — glasswool and polyester ceiling batt systems — scroll to view all
Bradford Gold R4.1 Ceiling Batts
R4.1 glasswool ceiling batt — AS/NZS 4859 — NCC compliant
System Description
Bradford Gold R4.1 Ceiling Batts are CSR Bradford's standard glasswool ceiling insulation product and one of the most widely specified ceiling batt systems in Australian residential and Class 2 strata construction. The R4.1 value slightly exceeds the NCC minimum R4.0 requirement for ceiling insulation in climate zones 4–6 — providing a margin above the minimum and making Bradford Gold a compliant product for all NCC climate zones that require R4.0 or higher. Available in 430mm width for 450mm joist spacing and 580mm width for 600mm joist spacing. Both widths are available in standard lengths for ease of installation between ceiling joists. Bradford Gold is a glasswool product — it contains glass fibres that can cause skin and respiratory irritation during installation and require PPE (long sleeves, gloves, P2 dust mask). Installation is at ceiling joist level — between and over ceiling joists where required — not in the roof space under tiles. Bradford Gold R4.1 is the benchmark ceiling batt product against which alternative brands are commonly compared. Confirm current product R-value, dimensions, and NCC compliance with Bradford before specifying — the product designation (Gold) and R-value have been consistent but confirm the current TDS before ordering.
Technical Properties
- Glasswool ceiling insulation batt — R4.1 — AS/NZS 4859 classified
- Exceeds NCC minimum R4.0 ceiling insulation requirement for climate zones 4–6
- 430mm width for 450mm joist spacing — 580mm width for 600mm joist spacing
Limitations
- Glasswool product — causes skin and respiratory irritation — wear long sleeves, gloves, and P2 dust mask during installation
- Ceiling-level installation only — do not confuse with under-tile PIR sarking or reflective foil sarking which are installed under the tiles
- Must not block eave ventilation — do not pack batts into eave space without anti-ponding board and insulation stop
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Description
Bradford Polymax R4.0 is Bradford's polyester/recycled fibre ceiling insulation batt — an alternative to the Bradford Gold glasswool product. The primary practical difference is that Polymax is an itch-free product — it does not contain glass fibres and does not cause skin or respiratory irritation during handling and installation. This makes it a preferred product for installers who handle large volumes of insulation batts, and for homeowners who wish to top up or rearrange ceiling insulation themselves after installation. The R4.0 value meets the NCC minimum for climate zones requiring R4.0 at ceiling level. Polymax is not as widely distributed as Bradford Gold and may carry a small price premium — confirm current availability and pricing with Bradford or a local insulation supplier. The product is manufactured from recycled polyester fibres and is marketed as an environmentally preferable alternative within the Bradford range. Install at ceiling joist level between joists — not in the roof space under tiles. Confirm current product dimensions, R-value, and availability with Bradford before specifying.
Technical Properties
- Polyester/recycled fibre ceiling batt — R4.0 — AS/NZS 4859 classified
- Itch-free — no glass fibres — can be handled without long sleeves or respiratory protection
- Meets NCC minimum R4.0 ceiling insulation requirement for applicable climate zones
Limitations
- R4.0 — does not exceed NCC minimum — if specifying above minimum for energy performance, specify Bradford Gold R4.1 or R6 product
- May not be as widely stocked as Bradford Gold — confirm availability with local supplier before specifying
- Ceiling-level installation only — do not confuse with under-tile PIR sarking or reflective foil sarking
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Knauf Earthwool R4.0 Ceiling Batts
R4.0 glasswool ceiling batt — formaldehyde-free — Knauf ECOSE
System Description
Knauf Earthwool R4.0 Ceiling Batts are Knauf Insulation's glasswool ceiling insulation product for the Australian market. The Earthwool product range uses Knauf's proprietary ECOSE binder technology, which is a bio-based binder derived from natural rapidly renewable materials — specifically, it is formaldehyde-free. This distinguishes Earthwool from traditional glasswool products that use formaldehyde-containing resole binders. The ECOSE binder gives Earthwool its distinctive brown colour (rather than the pink or yellow of traditional glasswool). Knauf Earthwool R4.0 is classified to AS/NZS 4859 and meets the NCC minimum R4.0 ceiling insulation requirement for applicable climate zones. It is available through major hardware chains and insulation suppliers nationally as an alternative brand to Bradford Gold. Like all glasswool products, Earthwool can cause skin and respiratory irritation during installation — PPE is required. Install at ceiling joist level between joists — not under roof tiles. Confirm current product dimensions, R-value, and NCC compliance with Knauf Insulation before specifying.
Technical Properties
- Glasswool ceiling insulation batt with ECOSE bio-based binder — formaldehyde-free
- R4.0 — AS/NZS 4859 classified — meets NCC minimum R4.0 ceiling insulation requirement
- Distinctive brown colour from ECOSE binder — readily identifiable in the ceiling space
Limitations
- Glasswool product — formaldehyde-free binder but glass fibres still present — PPE required during installation
- R4.0 — does not exceed NCC minimum — specify R4.1 or higher if margin above minimum is required
- Ceiling-level installation only — do not confuse with under-tile PIR sarking or reflective foil sarking
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
Fletcher Insulation Optimo R4.0
R4.0 glasswool ceiling batt — Fletcher Insulation — AS/NZS 4859
System Description
Fletcher Insulation Optimo R4.0 is Fletcher Insulation's glasswool ceiling insulation batt product for the Australian market. Fletcher Insulation is part of the Fletcher Building group and distributes insulation products nationally through timber merchants, hardware suppliers, and insulation specialists. The Optimo R4.0 ceiling batt is classified to AS/NZS 4859 and meets the NCC minimum R4.0 ceiling insulation requirement for applicable climate zones. It is positioned as an alternative brand option to Bradford Gold and Knauf Earthwool — all three products deliver comparable R4.0 glasswool ceiling insulation performance and meet NCC requirements. The primary differentiation between brands in this category is product availability through local suppliers, pricing at the time of ordering, and any specific installation features or dimensions that may suit the joist layout. Like all glasswool ceiling batts, Optimo requires PPE during installation — skin and respiratory irritation from glass fibres is expected without protection. Install at ceiling joist level — not under roof tiles. Confirm current product dimensions, R-value, NCC compliance, and pricing with Fletcher Insulation before specifying.
Technical Properties
- Glasswool ceiling insulation batt — R4.0 — AS/NZS 4859 classified
- Meets NCC minimum R4.0 ceiling insulation requirement for applicable climate zones
- Distributed nationally through timber merchants, hardware suppliers, and insulation specialists
Limitations
- Glasswool product — glass fibres present — PPE required during installation (long sleeves, gloves, P2 mask)
- R4.0 — does not exceed NCC minimum — specify Bradford Gold R4.1 if margin above minimum is required
- Ceiling-level installation only — do not confuse with under-tile PIR sarking or reflective foil sarking
PROCUREMENT SOURCES
Confirm suitability with the current manufacturer TDS before specifying or applying.
System Comparison
Side-by-side comparison of R4 ceiling batt systems. Confirm all product selections against the current manufacturer TDS and NCC climate zone requirements before specifying.
| Product | Brand | Material | R-value | Itch-free | Formaldehyde-free | Width options |
|---|---|---|---|---|---|---|
| Bradford Gold R4.1 | Bradford | Glasswool | R4.1 | No | No | 430mm, 580mm |
| Bradford Polymax R4.0 | Bradford | Polyester / recycled fibre | R4.0 | Yes | Yes | Confirm with Bradford |
| Knauf Earthwool R4.0 | Knauf | Glasswool — ECOSE binder | R4.0 | No | Yes — ECOSE binder | Confirm with Knauf |
| Fletcher Optimo R4.0 | Fletcher | Glasswool | R4.0 | No | Confirm with Fletcher | Confirm with Fletcher |
Do not confuse R4 ceiling batts with:
- Under-tile PIR sarking insulation board (Kingspan, Recticel and similar) — PIR boards are installed in the roof space under the roof tiles and over the sarking membrane — they are not ceiling batts and serve a different function — listed on the Sarking — PIR page
- Reflective foil sarking (Bradford Anticon, Fletcher Sisalation and similar) — reflective foil is installed under the roof tiles in the roof space — it is a combined sarking and radiant heat barrier product, not a bulk insulation batt — listed on the Sarking — foil page
- Mineral wool under-tile insulation (Bradford, Knauf, Rockwool under-tile products) — mineral wool under-tile products are installed in the roof space under tiles, not at the ceiling level — listed on the Sarking — mineral wool page
- R6 or higher R-value ceiling batts — R4.0/R4.1 is the NCC minimum for climate zones 4–6 only — climate zones 7 and 8 require higher R-values — confirm with certifier
- Wall insulation batts — wall batts have different widths, thicknesses, and R-values suited to wall stud spacing — do not substitute wall batts for ceiling batts
Disclaimer
Minimum R-value depends on NCC climate zone. Confirm with energy assessor or building certifier before specifying. Final product selection must be confirmed against the current manufacturer technical data sheet, project specification, joist spacing, and NCC Section J requirements. Ceiling insulation installation must comply with AS 3999. Do not rely on this reference as a substitute for professional engineering, energy assessment, or roofing consultant advice.