Fletcher Permatuff Building Blanket Medium Duty Metal Roof Insulation
R1.3, 15 m x 1200 mm x 55 mm (18 m²)
$126.00
Sale price
$126.00
Regular price
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Fletcher Permatuff Building Blanket Medium Duty Metal Roof Insulation
$126.00
Sale price
$126.00
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
Fletcher Permatuff Building Blanket is a glasswool roofing blanket with a medium duty, puncture resistant polyweave reflective foil facing, made for commercial and residential metal roofs. These rolls are R1.3, 55 mm thick and 1200 mm wide. Fletcher say the foil aids in minimising the risk of condensation in metal roofs.
Medium duty for wider purlin spans
Fletcher's AS/NZS 4200.2 duty table calls for medium duty or higher on unsupported spans over 900 mm and up to 1200 mm, which is where Permatuff MD fits. Light duty covers spans up to 900 mm. Over 1200 mm, fit safety mesh or similar underneath.
What R1.3 means on the roof
R1.3 is the Material R-value of the blanket. The foil needs a still air cavity of at least 20 mm to perform thermally. Compression cuts performance, so Fletcher recommend Roof Razor spacers on the purlins where the roof allows.
Fire limits
The faced blanket cannot be classified to AS 1530.1 as an assembly, so it is not suitable where non-combustible material is required. It complies with AS 3959 for Bushfire Attack Levels Low to 40 under metal sheet roofs.
Ordering and site notes
A 15 m roll covers 18 m², a 20 m roll 24 m². Allow about 5% for waste on a simple roof. Lay it over the purlins or roof battens, foil down, rolling each run over the 150 mm lap. Keep the rolls dry, and take care with the conductive foil near wiring. Not for tiled roofs. Full figures are in the table below.
Technical data
Fletcher Insulation technical data sheet (PDF)Sizes stocked
| Roll size | Thickness | Material R-value | Coverage per roll | Product code |
|---|---|---|---|---|
| 1200 mm x 15 m | 55 mm | R1.3 | 18 m² | 4020322 |
| 1200 mm x 20 m | 55 mm | R1.3 | 24 m² | 4020323 |
Thermal
| Material R-value | R1.3 m²K/W at 55 mm |
|---|---|
| Thermal resistance standard | Complies with AS/NZS 4859.1 |
| Reflective foil | Needs a still air cavity of at least 20 mm to perform thermally |
Compressing the blanket reduces its thermal performance, so give it room to recover to full thickness.
Duty selection for metal roofs (AS/NZS 4200.2, standard climate)
| Facing duty | Medium duty (MD) |
|---|---|
| Span up to 900 mm | Light duty may be used unsupported |
| Unsupported span over 900 mm up to 1200 mm | Medium duty or higher |
| Span over 1200 mm | Medium duty, with support (safety mesh or similar) below the insulation |
Permatuff MD covers the unsupported 900 to 1200 mm band without mesh, and spans over 1200 mm once mesh is fitted below.
Fire
| Combustibility (AS 1530.1) | Cannot be classified as an assembly. Not suitable where non-combustible material is required |
|---|---|
| Flammability index, facing foil (AS 1530.2) | ≤5 |
| Ignitability index (AS/NZS 1530.3) | 0 |
| Spread of flame index (AS/NZS 1530.3) | 0 |
| Heat evolved index (AS/NZS 1530.3) | 0 |
| Smoke developed index (AS/NZS 1530.3) | 2 (MD facing) |
| Group rating (AS 5637.1) | Group 1 (MD facing only) |
| Bushfire Attack Level (AS 3959) | Low to 40, under metal sheet roofs |
Fletcher state that where non-combustible material is required, laying the blanket and foil separately may comply.
Condensation and moisture
| Condensation | The reflective polyweave foil aids in minimising the risk of condensation in metal roofs |
|---|---|
| Moisture absorption | <0.2 % by volume at 50 °C and 95% relative humidity for four days |
Where the foil has to act as a vapour or air control layer, lap and tape the joins to AS/NZS 4200.2.
Material and handling
| Glasswool | FBS-1 Glasswool Bio-Soluble Insulation, up to 80% recycled content |
|---|---|
| Facing | Sisalation Multipurpose MD (432), puncture resistant polyweave reflective foil laminate |
| Foil lap | 150 mm overlap along the left hand side edge |
| Maximum service temperature (ASTM C411/C447) | Glasswool 340 °C, polyweave facing 70 °C |
| Electrical | Foil laminate is electrically conductive |
| Environmental | Zero ODP, no harmful levels of VOCs released |
Limits of use
| Weather | Keep dry at all times. Not to be exposed to weather before, during or after installation |
|---|---|
| Humidity | Not suitable where high humidity is present within the building |
| Tiled roofs | Not suitable under tiled roofs |
| Ventilation | Suitable roof ventilation must be installed to the NCC |
| Foil facing | Keep away from water and alkaline materials such as wet concrete. No pressure cleaners or mineral based cleaners |
| Modifications | Not permissible |
Compliance
| Energy efficiency | AS/NZS 4859.1 as referenced in NCC 2022 Volume 1 J4D3(1) and Volume 2 ABCB Housing Provisions 13.2.2 |
|---|---|
| Insulation fire indices | Does not exceed the Spread of Flame or Smoke Developed indices required by NCC 2022 Volume 1 S7C7 |
| Installation | AS 3999:2015 and Fletcher Installation Guide IG01 |
| Warranty | 10 years in commercial building applications, under Fletcher's Trade Customer Warranty for Commercial Products (trade customers only) |
Fitting notes
Install to AS 3999:2015 and Fletcher's building blanket installation guide IG01. On a house roof it can go over the roof battens with the glasswool in continuous contact with the underside of the roof sheeting. On a commercial roof, lay the blanket over the purlins the same way as the wire mesh, with the foil facing inward into the airspace below, and fix Roof Razor spacers to the purlins so the blanket can recover to its nominal thickness. Roll each new roll over the 150 mm foil lap with the glasswool butted firmly against the last one, and lap the foil at least 150 mm at all side and end joins. Where the foil must act as a vapour or air control layer, tape the laps to AS/NZS 4200.2 and seal tears and penetrations with Vapastop 883 Reinforced Foil Tape or equivalent. Check the roof sheet maker's maximum insulation thickness and allow enough sag for the blanket to recover. At the gutter on pitches above 10 degrees, trim the glasswool at the fascia and let about 25 mm of foil only drape into the gutter. Cut with a sharp knife and straight edge, not power tools. Keep the rolls dry. The foil is electrically conductive, so take care near electrical wiring and light fittings and ask a qualified electrician if in doubt.
Figures are taken from the Fletcher Insulation Technical Data Sheet for Permatuff, HTDS2 Revision 5, 11 November 2024, with span and fitting guidance from Fletcher Installation Guide IG01 Revision 4 (18 May 2026) and the Tuff Building Blanket brochure BR047 Revision 1, and warranty terms from the Fletcher Trade Customer Warranty for Commercial Products, TWAR3 Revision 1. The manufacturer document is linked above. Fletcher Insulation can change specifications without notice, so check the current sheet before specifying on a job.
Common questions
What purlin span can Permatuff MD cover without safety mesh?
Up to 1200 mm. Under Fletcher's AS/NZS 4200.2 duty table, unsupported spans over 900 mm and up to 1200 mm need medium duty or higher, and Permatuff MD is medium duty. Over 1200 mm, safety mesh or similar must be provided below the insulation.
What R-value does it give?
R1.3 is the Material R-value of the 55 mm blanket. The foil needs a still air cavity of at least 20 mm to perform thermally, and compressing the blanket reduces its thermal performance, so Fletcher recommend Roof Razor spacers where allowable.
How much area does one roll cover?
The 15 m roll covers 18 m² and the 20 m roll covers 24 m², both 1200 mm wide. Divide the roof area by the roll coverage and allow about 5% for wastage on simple areas, more on complex ones.
Can it be used where non-combustible material is required?
No. Fletcher state the faced product cannot be classified to AS 1530.1 as an assembly and will not be suitable where non-combustible material is required. Where that requirement exists, laying the blanket and foil separately may comply.
Is it suitable in a bushfire prone area?
Fletcher state it complies with AS 3959 for Bushfire Attack Levels Low to 40 under metal sheet roofs. Check AS 3959 for the install method that matches your BAL.
Which way does the foil face?
The foil faces inward, into the airspace below, except in tropical climates. On a commercial roof the blanket is laid over the purlins the same way as the wire mesh.
Does it help with condensation under a metal roof?
Fletcher say the reflective polyweave foil aids in minimising the risk of condensation that can form in metal roofs. Suitable roof ventilation still has to be installed to the NCC.
Can it go under a tiled roof or in a humid building?
No. Fletcher list it as not suitable under tiled roofs or where high humidity is present within the building, and it must be kept dry before, during and after installation.
Cannot see your question? Ask our team and we will get you an answer.
Answers use the Fletcher Insulation Technical Data Sheet for Permatuff (HTDS2 Revision 5) and Installation Guide IG01 Revision 4.
