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Vapour barrier buying guide

Updated: 21 October 2026

You are about to line a garden-room frame or a timber stud wall, and the amazon.co.uk results mix green sheets with a foil. A vapour barrier buying guide puts the moisture job first, then the thickness, then a width you can check against the title. Stars come after those three. This page does not name a winner. The [vapour barrier comparison](/hub/flooring-tools-and-accessories/vapour-barrier) lines up the five listings, and who each one suits is on the [best vapour barrier](/hub/flooring-tools-and-accessories/vapour-barrier/sub/vapour-barrier-best) page. Peter F. compared those listings. No sheet was lab-tested. A qualifying purchase can earn a commission at no extra cost to you.

You are about to line a garden-room frame or a timber stud wall, and the amazon.co.uk results mix green sheets with a foil.

Our top picks

B2C B2C yellow 0.2 mm, 20 m²

Best overall

B2C B2C yellow 0.2 mm, 20 m²
5.2/10about £19.79
View offer
ndcpolipak ndcpolipak 500 gauge, 2.7 m x 50 m

Rank 2

ndcpolipak ndcpolipak 500 gauge, 2.7 m x 50 m
8.0/10about £63.69
View offer
Just The Job Supplies Ltd Just The Job GVC2, 2.5 m x 5 m

Best value

Just The Job Supplies Ltd Just The Job GVC2, 2.5 m x 5 m
7.0/10about £12.60
View offer
On this page
  1. 1.What you are actually buying
  2. 2.Thickness before the price
  3. 3.Width, length and the clashes
  4. 4.What a standard line does not prove
  5. 5.Which kind of sheet to take next

What you are actually buying

A vapour control layer slows water vapour leaving a warm room before it reaches cold insulation. LABC Warranty treats 125 micron polythene as one accepted form on the warm side of a frame. A damp-proof membrane blocks liquid moisture from the ground. Approved Document C asks for polyethylene of at least 300 micrometres, 1200 gauge, below a ground-supported slab. The third object is a sauna facing. The B2C foil, B0H717S9WR, at £42.25 for 30 m², is that facing, not a thicker green stud-wall sheet. If the water comes from the ground, the thickness changes on the vapour barrier vs damp proof membrane page.

Thickness before the price

500 gauge, 125 micron and 125MU are the same stated warm-side thickness. NHBC Standards 2025, section 6.2.12, sets a minimum of 500 gauge on the warm side of external timber-framed walls. That does not make the sheet the membrane under a slab. 1200 gauge, about 300 micrometres, belongs with ground moisture. In this set, B084FM2VF2 states 500 gauge at £63.69. B0DTKQ7FW2 at £12.60 and B0DLBDRDXV at £15.69 state 125 micron, with no EN 13984 line. The yellow sheet states 0.2 mm with a tolerance of ±30% at £19.79, so the film can be thinner than 200 micrometres.
B2C B2C yellow 0.2 mm, 20 m²

Testsieger

B2C B2C yellow 0.2 mm, 20 m²
5.2/10about £19.79
View offer

Width, length and the clashes

A timber-frame roll is often sold at 2.7 m wide so one drop covers a storey. On B084FM2VF2 one verified UK review says the sheet was 2.45 m wide, and another reports holes at the folds. Measure the first metre before you cut a wall. GVC2 is titled 2.5 m by 5 m, while the dimension line reads 1000 by 250 by 0.01 cm, and two UK reviews say it arrived folded. GVC4 is titled 4 m wide and 5 metres, and the dimension line shows 400 cm without the 5 m length. The yellow sheet’s coverage field says 20 m², while the title also says 2 m by 50 m.

What a standard line does not prove

EN 13984 is the product standard for a vapour control sheet. In this set only B084FM2VF2 states it, as a CE mark under the Damplas name. That line does not mean your floor complies. LABC’s May 2025 note still wants the layer on the warm side, and cold-deck flat roofs sit outside that warranty except areas of 3 m² or less. Where the sheet is also the air barrier, Approved Document L expects a taped overlap. The staple sequence is on how to fit a vapour control layer.

Which kind of sheet to take next

A full timber frame points at B084FM2VF2, with the 2.45 m review left in the open. A single wall can use B0DTKQ7FW2 at £12.60, or B0DLBDRDXV at £15.69 when you want a stated 4 m width. Neither names EN 13984. The yellow film is the 20 m² coverage field. The foil stays with the sauna. None of these five is a stated 1200 gauge damp-proof membrane.

Common questions

Is 500 gauge the same as 125 micron?
Yes, as these sheets print them. 500 gauge, 125 micron and 125MU are the warm-side thickness on the green rolls here. 1200 gauge is the other pair, about 300 micrometres, and that is the minimum polyethylene in Approved Document C below a ground-supported slab. A listing that says 0.2 mm, as the yellow sheet does, is a third figure, with a stated tolerance of ±30%.
Do I buy 2.7 m width or 4 m width?
Buy the width that covers the drop, then check the dimension line. A 2.7 m roll is the usual timber-frame drop. A 4 m title, on Just The Job GVC4, is a short wide cut, and the dimension line shows 400 cm without confirming 5 m of length. If a review of the 2.7 m title reports 2.45 m, measure before you set the laps, because 2.45 m by 50 m is also a real trade size.
Does a CE or EN 13984 line mean the floor complies?
No. EN 13984 is a product standard for a vapour control sheet. In this set only the ndcpolipak roll states it. Whether a floor or a wall complies depends on position, laps and the rest of the build-up. LABC’s cold-deck limit of 3 m² is a warranty condition, not a pass mark you can claim from a CE line on a bullet.
Is a short £12.60 cut enough for one wall?
It can be, when the wall is small and you measure what arrives. Just The Job GVC2 is listed at £12.60 as green 125 micron, titled 2.5 m by 5 m. The dimension line can be read as 10 m by 2.5 m, two reviews say it arrived folded, and there is no EN 13984 line.
What do I still need if the sheet is also the air barrier?
Laps on supports, a tape meant for the sheet, and a repair before the plasterboard. Approved Document L describes overlap and taping where the vapour control layer is the air barrier. The government’s internal-wall-insulation guidance names duct tape, gaffer tape, expanding foam and decorator’s caulk as products that do not make a robust air barrier.

Related pages

Vapour barrier under laminate

Vapour barrier

Best vapour barrier: the 500 gauge roll to measure

How to fit a vapour control layer on the warm side

Vapour barrier or a damp-proof membrane: the split

Sources

Public UK sources used for this comparison. Listing prices, stars and review counts are the amazon.co.uk lines kept with these five products. Shelf date 19 October 2026.

  1. Approved Document C, 2013 (retrieved October 2026)
  2. Approved Document L Volume 1 (retrieved October 2026)
  3. LABC Warranty vapour control layers (retrieved October 2026)
  4. NHBC 7.2.15 pitched roofs (retrieved October 2026)
  5. BS EN 13984:2013 (retrieved October 2026)
  6. NDC Polipak damp proofing (retrieved October 2026)
  7. Wickes Damplas VCL sheet (retrieved October 2026)
  8. Wickes laminate flooring guide (retrieved October 2026)