Repair Systems — 04 — Roofing Defects
Anti-condensation blanket systems — metal sheet roof
Bradford Anticon and equivalent glasswool/foil blankets are installed directly under metal sheet roofing on purlin tops to control condensation and contribute thermal resistance for NCC Section J compliance. The blanket alone does not guarantee NCC compliance — a thermal assessor must confirm the total roof assembly R-value for the applicable climate zone.
Anti-condensation blanket — what it is and where it goes
Anti-condensation blanket (commonly called Anticon after the Bradford brand) is a glasswool insulation blanket with a metallised foil facing, installed directly under metal sheet roofing on top of the purlins. It reduces the risk of condensation forming on the cold underside of the metal sheet by providing a thermal break, and contributes an R-value to the total roof assembly for NCC Section J energy efficiency compliance.
Technical Reference
Condensation control function, NCC Section J compliance, installation method and blanket replacement under existing sheets
Product Reference
3 products — Bradford Anticon (primary), Knauf equivalent and other glasswool/foil blankets
Bradford Anticon
Glasswool anti-condensation blanket with foil facing; 60mm, 75mm, 90mm thickness; installed under metal sheet on purlins; NCC compliant thermal and condensation control
Product type
Metal roof anti-condensation blanket — glasswool/foil — NCC compliant
System description
Bradford Anticon is the market-leading anti-condensation blanket for metal sheet roofing in Australia, used under Colorbond, Zincalume and other metal sheet profiles on purlins. The product is a glasswool blanket with a foil facing on the room-side surface that provides a condensation-control layer and a contribution to the total roof assembly thermal resistance. Anticon is installed by rolling it out across the purlin tops before the metal sheets are fixed — the sheets clamp the blanket against the purlins, and the foil face hangs into the roof cavity. Available in 60mm, 75mm and 90mm thicknesses with corresponding R-values; 75mm is the most widely specified for Class 2 strata and commercial metal roof applications.
Technical properties
- Material: glasswool blanket with metallised foil facing
- Thicknesses: 60mm, 75mm, 90mm — confirm current range from Bradford TDS
- R-values: approximately R1.3 (60mm), R1.5 (75mm), R2.0 (90mm) for blanket only — confirm from current Bradford TDS
- Total roof assembly R-value depends on additional insulation and air gaps — confirm NCC compliance with thermal assessor
- Foil face installed facing downward into roof cavity (away from sheet)
- Width: 1200mm roll — spans between purlins with overhang at laps
- Longitudinal laps: minimum 150mm overlap between rolls
- NCC Section J: confirm blanket R-value meets current NCC energy efficiency requirements for the climate zone
Limitations
- Anticon blanket alone may not meet NCC Section J requirements in all climate zones — confirm with thermal assessor
- Must not be compressed by purlins beyond allowable limit — compression reduces effective R-value
- Do not allow blanket to sag into the roof cavity — sagging creates cold spots and condensation risk
- Does not provide acoustic insulation — separate acoustic treatment required if sound control is specified
- Not suitable as the only condensation control in high humidity environments (e.g., pool rooms, industrial processes) — engineer review required
Procurement
Bradford Insulation distributors and major insulation merchants nationally. Available to trade through roofing merchants and insulation suppliers.
Confirm suitability with the current manufacturer TDS before specifying or applying.
Knauf Metal Roof Insulation Blanket
Glasswool anti-condensation blanket for metal roofing; foil-faced; 60mm–90mm thickness; equivalent to Bradford Anticon for NCC compliance
Product type
Metal roof anti-condensation blanket — glasswool/foil — NCC compliant
System description
Knauf Insulation Australia manufactures glasswool anti-condensation blankets for metal sheet roofing applications, equivalent in function and installation method to Bradford Anticon. The products are available in standard thicknesses with comparable R-values and are installed by the same method — rolled across purlin tops before sheet fixing, foil face down into the roof cavity. Confirm the current product name, available thicknesses, R-values and NCC compliance from the Knauf TDS before specifying as an alternative to Bradford Anticon.
Technical properties
- Material: glasswool blanket with foil facing
- Thicknesses: 60mm, 75mm, 90mm — confirm from current Knauf TDS
- R-values: comparable to Bradford Anticon — confirm from Knauf TDS
- Installation: identical to Bradford Anticon — foil face down, rolled across purlins
- NCC Section J compliant — confirm applicable R-value for climate zone
Limitations
- Confirm current product name and specifications from Knauf TDS before specifying
- Same NCC Section J compliance requirements as Bradford Anticon — confirm with thermal assessor
- Same installation limitations as Bradford Anticon — do not compress, do not allow sagging
Procurement
Knauf Insulation distributors nationally. Available through insulation merchants and roofing suppliers. Confirm local availability before specifying.
Confirm suitability with the current manufacturer TDS before specifying or applying.
Other glasswool/foil blanket products
Other anti-condensation blanket products for metal roofing — confirm NCC compliance, R-value and suitability from manufacturer TDS before specifying
Product type
Metal roof anti-condensation blanket — confirm from manufacturer TDS
System description
Other manufacturers supply glasswool anti-condensation blankets for metal roofing. All products of this type function on the same principle: a glasswool blanket with a foil facing, installed under the metal sheet on purlin tops. When specifying any brand, confirm the R-value, NCC Section J compliance for the applicable climate zone, available thicknesses, and roll widths from the manufacturer TDS. The key selection criteria are the declared R-value, the total roof assembly R-value achievable, and the NCC compliance pathway.
Technical properties
- Material: glasswool blanket with metallised foil facing
- Installation: foil face down, rolled across purlins before sheet fixing
- Confirm R-value, thickness, roll width and NCC compliance from manufacturer TDS
Limitations
- Must be NCC Section J compliant for the applicable climate zone — confirm before specifying
- Same installation requirements as Bradford Anticon and Knauf — no compression, no sagging
- Confirm Australian distributor and local availability before specifying
Procurement
Various insulation merchants and roofing suppliers. Confirm local availability before specifying.
Confirm suitability with the current manufacturer TDS before specifying or applying.
Brand Equivalence
Bradford Anticon and Knauf equivalent are functionally interchangeable glasswool/foil blankets — confirm R-value from manufacturer TDS for NCC compliance.
| Product A | Product B | Equivalence note |
|---|---|---|
| Bradford Anticon 75mm | Knauf equivalent 75mm | Functionally equivalent products — same glasswool/foil construction, same installation method. R-values are similar but confirm from the specific product TDS. Both are NCC Section J compliant at appropriate thicknesses. |
| Bradford Anticon 60mm | Bradford Anticon 90mm | Different thicknesses of the same product — selection is based on the required total roof assembly R-value for the climate zone. 75mm is the most commonly specified for Class 2 strata in temperate climates. Confirm with a thermal assessor for NCC compliance. |
System Comparison
Bradford Anticon vs Knauf vs other brands. Confirm R-values and NCC compliance from current manufacturer TDS.
| Attribute | Bradford Anticon | Knauf Equivalent | Other brands |
|---|---|---|---|
| Material | Glasswool + foil | Glasswool + foil | Glasswool + foil (confirm TDS) |
| Common thickness | 60 / 75 / 90mm | 60 / 75 / 90mm | Confirm from TDS |
| Approx R-value (75mm) | ~R1.5 (blanket only) | ~R1.5 (confirm TDS) | Confirm from TDS |
| Foil face direction | Face down (cavity side) | Face down (cavity side) | Face down (cavity side) |
| Roll width | 1200mm | Confirm TDS | Confirm TDS |
| NCC Section J | Compliant (confirm zone) | Compliant (confirm zone) | Confirm from TDS |
| Installation | Rolled over purlins | Rolled over purlins | Rolled over purlins |
Do not confuse anti-condensation blanket with:
- Acoustic insulation — Anticon and equivalent blankets are not acoustic products. Separate acoustic insulation (e.g., Bradford SoundScreen) is required where acoustic performance is specified.
- Ceiling insulation — Anticon is installed under the metal sheet (above the purlins) not in the ceiling cavity. Ceiling insulation (batt or blow-in) is a separate product installed in the ceiling plane below. Both may be required for NCC Section J compliance.
- Sarking membrane — reflective foil sarking (e.g., Bradford R-MD, Anticon foil) is a separate product to the Anticon glasswool blanket. On pitched tiled roofs, sarking is installed under the battens. For metal roofing, the Anticon blanket provides the foil layer — a separate sarking membrane is not normally required under metal sheet.
Disclaimer
This page provides general technical information only. NCC Section J compliance must be confirmed by a qualified thermal assessor for the specific building, climate zone and roof assembly. R-values stated are approximate blanket-only values — total roof assembly R-value depends on the complete assembly. Do not rely on this reference as a substitute for professional engineering or thermal assessor advice.