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Vapour barrier tape vs foil tape

Updated: October 2026

Your amazon.co.uk search for a loft sheet is full of silver rolls that mention ducts, flues and heat. Vapour barrier tape vs foil tape is the split between those aisles. One product closes a polythene air and vapour control layer. The other is built for metal ductwork. The Products Compared editorial team looked at the kept membrane listings on 16 October 2026 and at why foil HVAC rolls were removed from that set. A qualifying purchase can earn a commission at no extra cost to you. Foil is not banned. It belongs when the membrane system names it. The rolls that stayed are on the [vapour barrier tape comparison](/hub/site-barriers/vapour-barrier-tape).

Your amazon.co.uk search for a loft sheet is full of silver rolls that mention ducts, flues and heat. Vapour barrier tape vs foil tape is the split between those aisles.

Our top picks

tesa tesa 60077, 50 mm

Best overall

tesa tesa 60077, 50 mm
8.2/10about £30.84
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DuPont Tyvek AirGuard 1310V, 60 mm

Rank 2

DuPont Tyvek AirGuard 1310V, 60 mm
8.6/10about £28.00
View offer
Ealyder Ealyder polyethylene, 100 mm

Best value

Ealyder Ealyder polyethylene, 100 mm
6.8/10about £17.99
View offer
On this page
  1. 1.Two products that share the word vapour
  2. 2.When a foil or metallised tape belongs
  3. 3.When the silver roll is the wrong buy
  4. 4.What to do with a duct, and what to do with a sheet
  5. 5.Three jobs, three rolls

Two products that share the word vapour

An AVCL tape is a single-sided accessory for the warm-side sheet. Tyvek's UK data sheet for AirGuard 1310V describes an internal tape, with a service band of about −40°C to 70°C. tesa's UK note for 60077 describes a polyethylene tape for vapour-barrier foils, including cable collars. Those rolls are meant to stay on plastic film at room temperature, behind plasterboard. Aluminium foil HVAC tape is doing something else. In the batch behind this category, foil listings aimed at ducts, flues and heat carried temperature lines up to 180°C. That number is a duct claim. It does not make the adhesive right for polythene, and it does not matter behind plasterboard. The sheet does the vapour job. The tape only keeps the sheet continuous.

When a foil or metallised tape belongs

Novia's vapour-control page is the fair case for foil. After butyl at least 30 mm wide in a 150 mm lap, Novia allows a single-sided aluminium foil tape or a metallised BOPP tape to hold the lap, with staples through the butyl. That foil is a named second step, the cover rather than the only tape. DuPont's UK tape selector draws the same line. Metallised tape is a separate style from AirGuard 1310V. If your membrane pack lists a metallised cover tape, buy that accessory. If it lists 1310V or another AVCL tape, a HVAC foil roll is a substitution you have invented. Face tape, foil or not, does not seal staple holes from behind. The how to tape a vapour barrier page has that sequence.
tesa tesa 60077, 50 mm

Testsieger

tesa tesa 60077, 50 mm
8.2/10about £30.84
View offer

When the silver roll is the wrong buy

The silver roll is the wrong buy when you are closing the polythene lap and the system does not name foil. Eight foil listings were removed from this category because they were aimed at ducts, flues and heat. They are not hidden alternatives if the AVCL tape is out of stock. A temperature line written for a heating duct does not tell you the adhesive will still be on polythene after the plasterboard goes on. A neat foil strip can still release on a dusty or flexing sheet. Proctor allows small scuffs to take their named system tape, not generic HVAC foil. Width and length for the kept rolls are on the buying guide.

What to do with a duct, and what to do with a sheet

Use a foil or metallised tape when the membrane system specifies it as the cover over butyl. Use an AVCL tape when you are closing the sheet and the maker does not ask for foil. If you already own a silver duct roll, leave it for metal joints the tape's own listing describes. The loft page then stops you using any of those tapes to block a ventilation path.

Three jobs, three rolls

Foil over butyl when the system names that cover. AVCL tape when the job is the polythene lap. HVAC foil when the job is a duct. One roll does not honestly cover all three. A low moisture-vapour line on silver tape does not replace the sheet, and a high temperature line does not prove the adhesive will stay on polythene.

Common questions

Can I use the silver duct tape I already have?
Only if that roll is the cover tape your membrane system names, usually over butyl. A leftover HVAC roll is specified for ducts, not for a polythene lap. Adhesion to metal and a high temperature line do not tell you it will stay on a flexing sheet. If the system does not name foil, buy the AVCL tape and keep the silver roll for ductwork.
Why do roofers use foil tape at all?
Because some vapour-control systems specify it as the second step. Novia, after butyl in the lap, allows a single-sided aluminium foil tape or metallised BOPP to hold the joint. That is a named accessory on top of a gasket. It is not an invitation to pick any silver roll from the duct aisle, and it does not remove the butyl under the staples.
Is foil tape more heat proof, and does that matter behind plasterboard?
Foil HVAC listings in the rejected batch quoted lines up to 180°C. DuPont's UK band for 1310V is about −40°C to 70°C. Behind plasterboard you are nowhere near flue temperatures. The heat claim does not answer whether the adhesive suits polythene. Match the sheet, and treat the temperature line as evidence of a different job.
What is the difference between a cover tape and the only tape?
A cover tape holds a lap that already has a gasket, often butyl, with staples through that gasket. The only tape, in a careless install, is one face strip expected to seal the overlap and the staple holes. Face tape, foil or polyethylene, only does the first of those if the sheet is flat and pressed. The holes need the layer behind them.
Is a low moisture-vapour claim on foil tape enough?
No. The vapour control layer is the sheet, as Approved Document C defines it for England. A low moisture-vapour line on the tape does not keep a lap sealed if the adhesive leaves the polythene, and it was not enough to keep duct-style foil in this set. Seal the sheet with the tape the system names.
What should I buy for a heating duct instead?
Buy a foil or HVAC tape whose listing names ducts, the metal, and a temperature band that matches the duct. That product was removed from this comparison on purpose. Do not use the AVCL rolls here as flue tape, and do not use the duct roll as the only seal on a loft sheet unless your system says that cover, over butyl, is the detail.

Related pages

Best vapour barrier tape

Vapour barrier tape

Vapour barrier tape buying guide for sheet and width

How to tape a vapour barrier so the lap stays shut

Vapour barrier tape in a loft: leave the eaves open

Sources

Public UK sources from the research digest. Listing prices, stars, and review counts are the amazon.co.uk lines stored with these four ASINs. Page updated October 2026.

  1. Approved Document C — Requirement C2 and the vapour control layer (retrieved October 2026)
  2. BSI BS 5250:2021 — Management of moisture in buildings (retrieved October 2026)
  3. IKO note on BS 5250:2021 (retrieved October 2026)
  4. A. Proctor Group — installing air and vapour control layers (retrieved October 2026)
  5. Novia vapour control layers (retrieved October 2026)
  6. DuPont UK TDS, AirGuard tape 1310V (retrieved October 2026)
  7. tesa UK 60077 note (retrieved October 2026)
  8. Passivhaus Trust airtightness guide, June 2020 (retrieved October 2026)