Underlay for concrete floor
Updated: 20 October 2026
The screed looks pale and hard, and a gold roll promises a damp-proof layer for about £30. Underlay for a concrete floor can include a vapour-control film, and only after the slab is dry enough for the flooring you are laying. A gold colour does not measure moisture. One UK review on a short gold roll describes foam that filled with water and a laminate that lifted, with no leak in the room. That is the failure this page is about. The six listings and their prices are the [5mm acoustic underlay comparison](/hub/flooring/5mm-acoustic-underlay). If you buy through our amazon.co.uk links, we may earn a commission at no extra cost to you. We used Quick-Step UK, Wickes, Forbo UK, and the product bullets. We did not meter a slab.
The screed looks pale and hard, and a gold roll promises a damp-proof layer for about £30.
The screed looks pale and hard, and a gold roll promises a damp-proof layer for about £30. Underlay for a concrete floor can include a vapour-control film, and only after the slab is dry enough for the flooring you are laying. A gold colour does not measure moisture. One UK review on a short gold roll describes foam that filled with water and a laminate that lifted, with no leak in the room. That is the failure this page is about. The six listings and their prices are the 5mm acoustic underlay comparison. If you buy through our amazon.co.uk links, we may earn a commission at no extra cost to you. We used Quick-Step UK, Wickes, Forbo UK, and the product bullets. We did not meter a slab.
Our top picks
| Badge | Product | Foil on the listing | Coverage | Thickness on the listing | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Royale Royale Sonic Gold 5 mm | Not stated | 15 m² | 5 mm | 8.3 | about £29.34 | View offer |
| Best value |  AcuStick AcuStick sonic gold 15 m² | Stated | 15 m² | 5 mm | 8.1 | about £29.50 | View offer |
| Alternative |  FloorPro FloorPro Smoothfit 7.5 m² | Stated | 7.5 m² | 5 mm / 0.01 m | 4.8 | about £21.50 | View offer |
On this page
Test before any roll
Write down a number before you unroll anything. Quick-Step’s UK guidance for a moist subfloor sets cement screed at under 2.5% CM or 75% relative humidity, and anhydrite at under 0.5% CM or 50% relative humidity. With underfloor heating those tighten to 1.5% CM or 60% relative humidity on cement, and 0.3% CM or 40% relative humidity on anhydrite. Record the reading, the method, and the date.
New screed needs time as well as a meter. Quick-Step’s rule of thumb is about a week per centimetre up to 4 cm, then slower. A 5 cm screed is a reason to wait and then measure. Heating in the slab is turned through a commissioning cycle before the floor goes down.
Wickes uses an overnight polythene square as a rough look, and a moisture meter as the real check, with figures they state as 12% on a prong reading or 3% on their meter. Those percentages are not the CM method and they are not 75% relative humidity. Do not average them into one dry-enough line. If the polythene square comes up fogged, you have a warning, not a pass. Forbo’s UK notes want the slab below 75% relative humidity, and an older slab still needs a structural damp-proof membrane or a surface damp-proof membrane if you cannot show one. Carpet breathes. Laminate on a film does not.
What a gold foil is
A stated gold foil is a vapour-control layer for residual moisture in a slab that has already passed. It slows water vapour. It does not stop liquid water, and it does not replace a liquid damp-proof membrane on a floor that has failed the reading. EPLF’s underlay bulletin talks about a vapour barrier in the region of an sd value of 75 m on mineral subfloors. These amazon listings do not print an sd value. Gold foil moisture membrane in a bullet is a description of a film, not that test result.
If the reading fails, the next step is a surface damp-proof membrane the flooring maker accepts, or a specialist, and then a new test. Laying the roll and hoping is how the Smoothfit kitchen review ends: foam full of water, laminate lifted, no leak in the room, and wasted materials the reviewer put above £500. One kitchen is not a rate for every gold product. It is enough to refuse the idea that the colour is the membrane.
Once a cement screed has passed, and the listing states a foil, that film can be the vapour layer. Untaped seams are a gap in the film every metre. AcuStick names Barrier Pro X tape and does not include it. Underfloor heating makes the moisture limits tighter and adds a heat limit. Floor plus underlay is commonly capped at 0.15 m²K/W. The XPS boards claim up to 2.2 tog, about 0.22 m²K/W before the floor. The Network roll’s 0.9 tog is about 0.09 m²K/W for the underlay alone. The sum sits on the buying guide.
Which listings state a foil
AcuStick’s 15 m² roll states a gold foil moisture membrane, 24 dB, and wood or laminate, at £29.50. The 30 m² listing repeats the same claims and the same review text. Smoothfit states a gold foil damp-proof membrane on a titled 7.5 m² roll, and it is the listing with the waterlogged-foam review. The title says 5 mm and the thickness field says 0.01 m. Network states a gold foil, 25 dB, 0.9 tog, and vinyl, with 5.0 from one rating and no review text. Those are the listings where a foil is a bullet, not a guess.
Royale, 4.6 from 800 ratings and £29.34 for 15 m², does not state a foil or a decibel figure. Reviewers describe a gold face and an overlap used on screed. That is a review observation. If your plank sheet requires a manufacturer-stated vapour layer, Royale’s bullets do not give you one. On a concrete floor that needs a stated membrane, the stated-foil roll is the honest buy, and you still test the slab first. Who each listing suits is on the best 5mm acoustic underlay page.
The XPS pack states no foil. It is 21 boards, 9.79 m², up to 2.2 tog, 23 dB, 4.5 from 336 ratings. On a slab you still need a separate vapour plan if the flooring maker requires one. Reviews also say the foam holds water if moisture gets in. A foil does not level the slab. Hollows need a levelling compound compatible with the membrane, after the moisture test.
Timber is a different rule
If the floor under your laminate is timber or floorboards, do not copy this concrete method. EPLF’s bulletin warns that a vapour-tight film on wood can trap moisture in the boards. A gold roll that is right on a dry screed can be the wrong layer on a suspended timber floor. Leave the boards able to breathe unless the flooring maker gives you a different written instruction for that build.
A dry slab and a stated foil still leave you with a soft 5 mm foam. Vinyl clicks unclip on that foam in the AcuStick reviews. Dry and suitable are different words. Pass the moisture test, then check the plank type. Laying the sheets, the tape, and the wall gap come after that pass.
Common questions
Does gold foil replace a damp-proof membrane?
It replaces nothing until you have a passing moisture reading. On a dry-enough cement screed, a foil the listing actually states can act as the vapour-control layer. On a failed reading, or on an older slab with no effective membrane, Forbo’s UK notes point to a structural membrane or a surface damp-proof membrane. The Smoothfit review of water inside the foam is what hoping the foil copes looks like.
What moisture reading should you see before laminate?
Use the method your flooring maker prints. Quick-Step UK: cement screed under 2.5% CM or 75% relative humidity, anhydrite under 0.5% CM or 50% relative humidity, and tighter with underfloor heating (1.5% CM or 60% RH on cement, 0.3% CM or 40% RH on anhydrite). Wickes’s meter figures are a different test. Do not mix the percentages.
What if the screed is new?
Wait, then measure. Quick-Step’s guide suggests about a week per centimetre for the first 4 cm, then longer, and a meter at the end. A new heated screed also needs its commissioning cycle. Colour and surface hardness are not a CM reading. Lay the underlay after the number passes, not after the plasterers have left.
Which of these six listings state a foil?
AcuStick, both the 15 m² roll and the twin-pack title, Smoothfit, and the Network roll state a gold foil. Royale’s bullets do not, although reviewers mention a gold face. The XPS boards do not state a foil. A stated foil still needs a dry slab and taped seams.
What if the foam gets wet after the floor is down?
Lift the floor. Foam that has held water, as in the Smoothfit kitchen report and in XPS reviews, will not dry usefully under a locked laminate. The planks that have swollen or lifted are often scrap. Find the moisture path, which may be the slab rather than a pipe, before you lay anything else. A fitter or a damp survey is cheaper than a second floor.
When do you stop and use a liquid DPM or a fitter?
When the reading is over the maker’s limit, when you cannot show a membrane in an older slab, when the floor is too uneven to float, or when heating plus this underlay cannot stay at or under about 0.15 m²K/W. A liquid or surface damp-proof membrane is a specified system, not a thicker gold roll. After it cures and a new reading passes, you can lay.
Related pages
Sources
Public UK sources listed in the research digest. Listing prices, stars, and review counts are from amazon.co.uk on 19 October 2026.
- Approved Document E, GOV.UK (retrieved 19 October 2026)
- East Lindsey Guidance Note 53, resistance to the passage of sound (retrieved 19 October 2026)
- Scottish Technical Handbook 2022, section 5.1, noise separation (retrieved 19 October 2026)
- Technical Booklet G 2012, Northern Ireland (retrieved 19 October 2026)
- SITMA, sub-floor testing requirements under Approved Document E (retrieved 19 October 2026)
- BSI, BS EN 16354:2018 laminate floor underlays (retrieved 19 October 2026)
- EPLF underlay materials bulletin, December 2022 (retrieved 19 October 2026)
- Quick-Step UK, vinyl with underfloor heating or cooling (retrieved 19 October 2026)