A shed wall takes a different product to a shed roof, and it is fixed differently. On a steel girt wall the choices are a foil faced blanket behind a lining, a reflective membrane fixed to the girts before the sheeting goes on, rigid board outside a framed wall, or batts where a stud wall exists. Almost all of it goes in before the cladding.
In short
- Ametalin's RT 1.2 winter for ThermalBrane GP is the only shed wall system figure we have, and it assumes 90 mm studs.
- Nobody publishes a total R-value for a girt wall with the sheeting screwed to the girts.
- Insulshed 50 is named after sheds and publishes no R-value at all.
- Tek screws no more than 450 mm apart is the only published steel fixing spacing. Cap nails are for timber.
- Nearly every option goes on before the cladding, which is why a wall is harder to retrofit.
The roof is the first fix and the biggest win, and insulating a metal shed roof covers it. This one is about the walls.
What a shed wall is made of
A steel shed has columns at intervals and horizontal girts between them, with the wall sheet screwed to the front face of the girt. The fixing plane is that girt face, so anything between sheet and girt is clamped at every screw.
Three walls need telling apart. A girt wall not yet sheeted, where every option is open. A girt wall already sheeted, where a membrane can only go on the inside face of the girts. And a framed wall of studs or top hats, where batts behave as in a house.
How a wall is not a roof
Beyond the west wall taking the afternoon sun, three things change once the surface is vertical.
The night side is weaker. Night sky radiation is set out in condensation in metal roofs. A vertical wall has less view of the open sky, so that driver is milder. Nobody publishes a dew point case for a shed wall. Bradford say a vapour barrier belongs on the warm side, and that a designer should run a hygrothermal analysis.
The bottom of the wall is wet. Rain splashes off the apron and the slab holds moisture. Ametalin take the membrane from top plate to bottom plate, and warn that aluminium foil must not contact wet concrete or mortar, because aluminium corrodes in alkali. Bradford say the same for Performa. No sheet gives a termination height or a flashing detail.
The girt is a cold line. Where the sheet screws down, steel touches steel through the build up. NCC 2022 Housing Provisions clause 13.2.3(7) covers the roof, asking for at least R0.2 where sheeting fixes to metal purlins. The wall equivalent is clause 13.2.5(5), the same R0.2 where lightweight cladding fixes to a metal wall frame. Both are set out in the R0.2 thermal break. Whether either reaches a Class 10a shed is a question for the certifier. One product for it is ThermalBreak 7, R0.21 uncompressed and R0.20 compressed. We also stock Kingspan AIR-CELL Insulbreak 70 and 90, which Kingspan rate for the R0.20 thermal break, and Insulbreak 55, which is not a thermal break grade.
What can go on the wall
The third column is the point. What a maker publishes for a wall is not always an R-value, and not always the same kind.
| Option | Thickness and roll | What the maker publishes, and what kind of figure | Fixing to steel | Facing the room |
|---|---|---|---|---|
| Kingspan AIR-CELL Insulshed 50 | 5 mm, 1350 mm rolls of 30 or 45 m² | No R-value at all. Reflectance 97 per cent, emittance E0.03 | No wall detail published, only a roof | Class 10a sheds and garages only |
| Trade Select ThermalBrane GP | 4 mm, 1500 mm rolls of 30 or 45 m² | Material R0.1, and the only shed wall system figure here, for a 90 mm stud wall: RT 1.2 winter, RT 1.0 summer, RT 1.7 and RT 1.5 lined | Tek screws at 450 mm, 150 mm laps | No Group Number published |
| Bradford Polyair Unicell | 4 mm in 1350 mm x 40 m (54 m²) or 1500 mm x 25 m (37.5 m²). 10 mm in 1350 mm x 22.25 m (30 m²) | Material R0.10 and R0.20 only, air gap excluded | No fastener type or spacing published. Framed walls, butted at the studs | Permitted exposed in Class 1 and 10, though the same sheet says it has no Group Number |
| Bradford Polyair Performa | 4 mm or 8.8 mm, 1350 mm rolls of 30 to 54 m² | Material R0.10 and R0.20 only | As Unicell, cladding the same workday | The 4 mm is Group 1. The 8.8 mm has none |
| Sisalation Foam Cell Resi Liner or Multipurpose | 5 mm or 8.4 mm, 1350 mm x 22.25 m (30 m²) | Material R0.11 and R0.25. System figures only for brick veneer R1.6, double brick R1.8 | Framed walls, lapped onto the 150 mm flap | Group 2 |
| EcoRoof foil faced blanket | 1200 mm wide: 55 mm R1.3, 75 mm R1.8, 100 mm R2.3, 130 mm R3.0 | Material R-value on the blanket | Over the girts before the sheeting | Group 1, but its own sheet says behind a lining |
| Kingspan Kooltherm K12 board | 25 to 80 mm, 2400 x 1200 mm boards, sold by the full Kingspan pack | Declared R1.10 to R3.60, and a steel framed wall total RT2.3 at 25 mm to RT3.5 at 50 mm stated for NCC Class 1 and 10a | Temporary clout nails, then treated softwood counter battens through the board into the studs, then cladding | No, the detail is lined |
| Wall batts, glasswool or polyester | 75 and 90 mm, plus 140 mm at R4.0 | Material R1.5 to R2.7 in a 75 or 90 mm stud | Friction fitted, tight all round | No, batts need a lining |
Facing the room is a fire question first, and Polyair Unicell contradicts itself. Page one says it suits roofs and walls as an exposed internal lining in Class 1 and Class 10. The limitations section says it has no Group Number to AS ISO 9705 and AS 5637.1 and is not suitable as an exposed lining. Bradford do not reconcile the two, so get it in writing before leaving Unicell showing. Ametalin also ask for an air space next to the foil, and Bradford exclude that gap from their declared R-value, so foil pressed flat does less than the box suggests.
The R-value question
Nobody publishes a total R-value for a bare colorbond wall. The closest is Ametalin's: one calculation in their sheet is headed commercial or shed wall, and the table on the same page calls the same case a steel stud framed wall with 90 mm studs, RT 1.2 winter and RT 1.0 summer, or RT 1.7 and RT 1.5 lined. It assumes studs a bare girt wall does not have, and it is worked to AS/NZS 4859.1:2002 in a document dated 2014.
Every other wall figure is for something else. Foam Cell's are brick veneer R1.6 and double brick R1.8. Kooltherm K12 runs RT2.3 at 25 mm to RT3.5 at 50 mm for Class 1 and 10a, the class a shed sits in, but the detail is a lined stud wall with board outside the frame.
Then there is the product named after sheds. The Insulshed 50 data sheet gives thickness, roll size, reflectance and emittance and stops. No R-value appears in it, the only detail drawn is a roof, and the word wall is not in the document. Our own page says shed roofs and walls, so confirm that with Kingspan.
What happens at the girt is unpublished too. Bradford say only that once compressed the material R-values are reduced and no longer meet the thermal break requirement. No percentage is given. The roof answer is a spacer, covered in stopping insulation sag.
How it is fixed to steel
Tek screws. Ametalin's method for ThermalBrane GP is the only steel wall fixing schedule we found. Install horizontally as a continuous membrane, anti-glare side out, top plate to bottom plate, fixings no more than 450 mm apart. Tek screws into steel, staples into timber, cap screws in high wind. Laps are 150 mm untaped or 50 mm taped.
Double sided fixing tape. Trade Select Double Sided Fixing Tape fixes membranes to steel frame stud work, 38 mm x 50 m, adhesion to steel of 20 N per 25 mm, applied between 10 and 40 degrees. Run a vertical strip on a clean dry member, align the membrane, then put anchor screws into the corners so wind cannot lift it. Tape every second member and around openings. Ametalin do not recommend it under a hot metal roof.
Gas driven pins and washers. ICCONS GTW25 steel washers are 25 mm across, 250 to a pack, fired with 22 mm Gripshank pins from a gas tool. At 300 mm centres a pack covers roughly 75 lineal metres.
Cap nails, which are the wrong tool here. Ametalin Cap Nails are a 25 mm polymer cap on a 25 mm ring shank nail, published for timber framework only: 300 mm centres on cavity walls, 150 mm direct to a stud. A colorbond wall is steel.
Nobody publishes a fixing schedule for a girt wall, a fastener count per square metre, or an unsupported span on a vertical surface. The only spans Bradford publish, 900 mm and 1200 mm, are roof cases.
New build against retrofit
Every installation instruction here assumes the membrane goes on before the cladding. Bradford are bluntest on Performa: the cladding should go on the same workday to comply with the warranty.
| Option | Shed being built or reclad | Shed already sheeted |
|---|---|---|
| Membrane or blanket over the girts | Fix to the frame, lap, then sheet | Not possible without taking sheets off |
| Membrane on the inside face of the girts | Possible, though outside is better | Possible with tape or pins, girt left uncovered |
| Rigid board outside a frame | Temporary clout nails, counter battens through the board, cladding | No, the detail needs the cladding off |
| Batts in a stud or top hat wall | Build the frame, fit batts, line it | Possible, but it means an inner frame and lining first |
Doing it properly later means a second wall inside the first. The general case is in retrofit against new build.
The slab, the flues and the doors
Ametalin state that within 500 m of the sea, or where foil may meet a corrosive atmosphere in a non-residential building such as an agricultural shed, foil should face an enclosed unvented air space. Bradford say Unicell is not suitable within 500 m of saltwater in a ventilated space.
Clearances appear in two sheets only. Kingspan ask for 100 mm clear of hot flues and light fittings for Insulshed 50. Ametalin ask for 50 mm clear of a hot flue for ThermalBrane GP, or whatever the flue maker specifies. The Kooltherm K12 sheet publishes neither. Insulshed 50 is damaged above 105 degrees, so keep welders away. These foil facings conduct electricity.
A big steel door undoes some of what the walls do. The only door method published in the set is Ametalin's: clean both surfaces, remove any anti-glare or painted finish, wipe with acetone or isopropyl alcohol, then run horizontal strips of double sided tape across the panels. It suits fixed panel or rigid doors only, because the movement of a roller door pulls the insulation off.
Working out how much
Wall area is easier than roof area: no pitch multiplier. Measure the perimeter, multiply by the height to the eaves, add the gable triangles. No source publishes a waste allowance for a wall, so work from the roll size and lap.
Worked example. A 12 m by 7 m shed, 3 m to the eaves, so a perimeter of 38 m.
- In ThermalBrane GP. The roll is 1500 mm wide and the lap 150 mm, so each run covers 1350 mm of height. Three runs cover the 3 m, which is 114 lineal metres. The 45 m² roll is 30 m long, so 4 rolls.
- In EcoRoof blanket. At 1200 mm wide with a 150 mm flap, each run covers 1050 mm. Three runs again, and the 55 mm roll is 15 m, so 8 rolls.
One correction on our own numbers. Our EcoRoof 130 mm variant is listed as R3.2 at 12 m², where the data sheet gives R3.0 in a 6 m roll, 7.2 m². Go by the data sheet.
We supply it, and we install batts, wall wrap and sarking
AWBM supplies shed wall insulation across Victoria and New South Wales, and we install batts, wall wrap and sarking. Send the shed size, the wall height, whether the sheeting is on and whether it will be lined. 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.
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Frequently asked questions
What goes on shed walls and how is it fixed?
A reflective membrane fixed to the girts before the sheeting, a foil faced blanket behind a lining, rigid board outside a framed wall, or batts in a stud wall. Fixing to steel is tek screws no more than 450 mm apart, double sided tape on every second member, or gas driven pins with 25 mm washers. Cap nails are timber only.
What is the best insulation for shed walls?
It depends on whether the shed is lined and whether the sheeting is on. For a lined workshop, a foil faced blanket such as EcoRoof from 55 mm at R1.3 to 130 mm at R3.0, or batts in a framed wall. For a storage shed, a membrane.
What R-value will a colorbond shed wall get?
Nobody in our range publishes a total R-value for a girt framed wall with the sheeting screwed to the girts. The closest is Ametalin's RT 1.2 winter and RT 1.0 summer for ThermalBrane GP, which assumes a 90 mm stud framed wall, or RT 1.7 and RT 1.5 once lined.
Can you insulate shed walls from the inside without taking the cladding off?
Partly. A membrane can be taped or pinned to the inside face of the girts, but the girts stay uncovered and that is not what the instructions describe. Doing it properly later means an inner frame and a lining.
Can shed wall insulation be left exposed on the inside?
Some of it. Bradford's 4 mm Polyair Performa is Group Number 1 and may be used as an exposed lining where the NCC specifies one. The Unicell statement permits it exposed in Class 1 and 10, then says in its limitations that it has no Group Number and is not suitable as an exposed lining, so confirm that one with Bradford. Foam Cell is Group 2. EcoRoof, K12 board and batts belong behind a lining.
Do shed walls sweat the way the roof does?
Less, because a vertical wall does not radiate to the open night sky the way a roof does, but it is not immune. Nothing published gives a dew point case for a shed wall. Bradford's rule is that a vapour barrier belongs on the warm side.
What happens where a shed wall meets the slab?
The membrane runs from top plate down to bottom plate, and aluminium foil must not touch wet concrete or mortar, because aluminium corrodes in alkali. Past those two instructions there is no published detail for a shed wall base, so agree that junction with the builder.
Can you insulate a roller door?
Not with the published method. Ametalin's garage door method, which wipes both surfaces with acetone or isopropyl alcohol before taping, suits fixed panel or rigid doors only, because the movement of a roller door pulls the insulation off. No maker we stock publishes an R-value for one.
Sources
- Kingspan Insulation, AIR-CELL Insulshed 50, KIAU0046 Issue 10, February 2025, and Kooltherm K12 Framing Board, KIAU0057 Issue 17, November 2024
- Ametalin and Trade Select, ThermalBrane GP, DTE-42682-5, copyright 2014, calculated to AS/NZS 4859.1:2002 with Amendment 1:2006
- Ametalin, ThermalBreak, APM-45758-2, copyright 2024, Double Sided Insulation Fixing Tape, TPM-45937-0, copyright 2025, and Cap Nails, APM-45726-9, copyright 2024. None of the three carries an issue date
- CSR Bradford Product Technical Statements, Polyair Unicell PTS120 Issue G and Polyair Performa XHD PTS118 Issue J. Both carry an issue letter and no issue date
- Fletcher Insulation, Sisalation Foam Cell Resi Liner, FTDS2 Revision 7, and Foam Cell Multipurpose, FTDS1 Revision 6, both 1 March 2023
- All Weather Insulation, EcoRoof Building Blanket, a document carrying no revision number and no issue date
- ICCONS Gas Insulation Technical Data Sheet 4002.5, which carries no issue date. The GTW25 washer has no manufacturer data sheet, so its figures come from ICCONS product data and the RM Industries price list of May 2026
- CSR Bradford price catalogue, 28 May 2026, for roll and batt sizes. The file linked as the Bradford glasswool data sheet is a safety data sheet
- NCC 2022 Housing Provisions clauses 13.2.3(7) and 13.2.5(5)
- AWBM catalogue product pages read live on 23 September 2026
General information for owner builders and trade, not a design or a compliance certificate. Whether a shed is covered by the energy efficiency provisions, and whether a wall junction needs a thermal break, depends on its classification and use. Confirm both with your builder or certifier. Manufacturers change specifications without notice, so read the current data sheet before ordering.