5mm underlay for laminate: the checks before you buy
Updated: 20 October 2026
You have laminate packs in a spare room and a search page full of 5 mm acoustic products, some of which are car mats. A 5mm underlay for laminate is the foam or board under a floating wood or laminate floor. Thickness does not prove the joints will stay shut, that a slab is dry, or that a neighbour will hear less. This page walks those checks in the order a UK fitter uses them. Prices for the six kept listings are on the [5mm acoustic underlay comparison](/hub/flooring/5mm-acoustic-underlay). Figures are amazon.co.uk prices from 19 October 2026. If you buy through our links, we may earn a commission at no extra cost to you. We did not run a laboratory sound test.
You have laminate packs in a spare room and a search page full of 5 mm acoustic products, some of which are car mats. A 5mm underlay for laminate is the foam or board under a floating wood or laminate floor.
You have laminate packs in a spare room and a search page full of 5 mm acoustic products, some of which are car mats. A 5mm underlay for laminate is the foam or board under a floating wood or laminate floor. Thickness does not prove the joints will stay shut, that a slab is dry, or that a neighbour will hear less. This page walks those checks in the order a UK fitter uses them. Prices for the six kept listings are on the 5mm acoustic underlay comparison. Figures are amazon.co.uk prices from 19 October 2026. If you buy through our links, we may earn a commission at no extra cost to you. We did not run a laboratory sound test.
Our top picks
| Badge | Product | Foil on the listing | Claimed sound | Stated tog | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Royale Royale Sonic Gold 5 mm | Not stated | Not stated | Not stated | 8.3 | about £29.34 | View offer |
| Best value |  AcuStick AcuStick sonic gold 15 m² | Stated | 24 dB | Not stated | 8.1 | about £29.50 | View offer |
| Alternative |  FloorPro FloorPro XPS 5 mm boards | Not stated | 23 dB | Up to 2.2 | 7.7 | about £24.77 | View offer |
On this page
What 5 mm is for
Five millimetres is a common thickness for a closed-cell foam roll with a gold-coloured film, or for a pack of XPS boards, under floating laminate or engineered wood. You want a little give and some warmth on a concrete bedroom. You do not want a wall panel, a car deadening mat, or a carpet underlay that only shares the words 5 mm and acoustic. In this set a floor underlay is a roll of about 15 m², a short roll of 7.5 m², or 21 boards covering 9.79 m².
Thicker is not kinder. Floor Depot’s notes say density matters more than the millimetre count, and they warn against Sonic Gold 5 mm under 7 mm laminate. A thin click plank has little stiffness of its own. Soft foam lets the joint rock. If your packs are that thin, read the plank sheet, then the laminate or click vinyl page. A 12 mm laminate on a flat, dry floor is a different case, and only if that maker allows about 5 mm underneath.
Support and moisture
Click joints need a firm bed. BS EN 16354:2018 sets a compressive-strength floor at 10 kPa, with a UK note that some end uses can work at 5 kPa if the maker states that use. None of the six amazon.co.uk listings print a compressive-strength figure. A bullet that only says 5 mm and acoustic does not tick the standard. If the plank maker names a minimum, that number outranks a comfortable feel in the shop.
On a cement screed, Quick-Step’s UK guidance asks for under 2.5% CM or 75% relative humidity, and tighter figures with underfloor heating. A gold foil, when the listing states one, is a vapour-control film on a slab that has already passed. It is not a cure for a wet floor. Royale’s bullets do not state a foil. AcuStick’s 15 m² roll, Smoothfit, and the Network roll do. The XPS boards do not. On timber the rule flips: the EPLF underlay bulletin says a vapour-tight film can trap moisture in the boards.
Measure the room before you trust a 15 m² label. UK reviews on the gold rolls include rolls short of the stated cover, including one measured under 12 m². A 3 m by 4 m room is 12 m² and still needs a cutting margin. Seam tape is named on the AcuStick and XPS listings and is not in the box. The laying sequence is on how to lay laminate underlay. The screed test is on the concrete floor page.
Sound figures and heating
A bullet that says 23 dB, 24 dB, or 25 dB is the seller’s claim. It is not, on these listings, an ISLam result. EPLF describes ISLam as an impact-sound improvement under a reference laminate, with at least 14 dB as a basic bar and 18 dB as a higher one. The test has a named floor build. Walking noise in the same room is a different measure. A crisp-packet crinkle is the room you are standing in, even if the flat below is quieter.
Approved Document E, for England, is about sound between dwellings, not a bedroom inside one house. East Lindsey’s note on that document puts new separating floors at a minimum of 45 dB DnT,w + Ctr airborne and a maximum of 62 dB L’nT,w for impact. Scotland’s domestic handbook 2022, section 5.1, asks at least 56 dB DnT,w and no more than 56 dB L’nT,w. Northern Ireland’s Technical Booklet G (2012) matches the England figures of 45 dB and 62 dB. Use the nation where the floor is. SITMA’s point is that a loose laminate underlay is not the soft covering used in a standard impact test.
Heat runs the other way from warmer underfoot. Floor plus underlay over underfloor heating is commonly capped at 0.15 m²K/W, the limit Quick-Step UK states. Ten tog equals 1 m²K/W, so up to 2.2 tog on the XPS boards is 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. Add the floor before you call either figure safe.
What to do with the six listings
Match the stated foil, tog, and recommended use to the floor you have. A printed decibel line is not a legal pass, and none of these six print compressive strength. If the plank maker allows about 5 mm on a flat, dry floor, use the table, then read who should skip each listing before you order two rolls for a room you have not measured. A specialist mat with a stated impact improvement, well above about £2 per square metre, is a different purchase. DEFRA’s good-practice range, hosted by Sandwell Council, put ordinary underlay around £1–£3 per square metre. That range is the guide’s, not a 2026 survey of every shop.
Common questions
Is 5 mm better than 3 mm?
Only if the flooring maker allows it and the underlay is firm enough for the click. Floor Depot warns that a 5 mm sonic gold foam under 7 mm laminate can open the joints, because the thin plank cannot bridge a soft bed. A thicker board can feel warmer on concrete. Warmth and joint support are different jobs, and a millimetre count does not settle both.
What does compressive strength mean for a click floor?
It is how much the underlay squashes under a set load. BS EN 16354:2018 uses 10 kPa as the specification floor, with a UK note that 5 kPa can be enough when the maker states the end use. None of these six listings print the figure. If your plank sheet names one, buy to that number. A soft feel in the hand is not a substitute.
Is a printed 24 dB an Approved Document E pass?
No. The 24 dB line on the AcuStick listing is a seller claim. Approved Document E judges the finished separating floor in the building, with different numbers in Scotland from England and Wales. ISLam, in the EPLF bulletin, is a laboratory improvement under a reference laminate, at least 14 dB for a basic bar. A bullet without that method is not either test.
When do you need a vapour layer?
On a mineral floor that is already dry enough for the flooring maker, and only with a film the listing states. Quick-Step UK uses under 2.5% CM or 75% relative humidity on cement screed, tighter with underfloor heating. On timber, a vapour-tight film can trap moisture, which is the EPLF warning. Royale’s bullets do not state a foil, so do not invent one from a gold colour reviewers describe.
Can a 2.2 tog board go over underfloor heating?
The XPS listing claims up to 2.2 tog, about 0.22 m²K/W for the boards alone. A combined cap of 0.15 m²K/W for floor plus underlay, as Quick-Step UK states, is already exceeded before you add the planks. Leave that pack off a heated floor unless the system designer accepts a higher resistance in writing.
Why do some 5 mm acoustic results turn out to be car mats?
The words are shared. Car deadening and wall foam use 5 mm and acoustic in titles, and some floor rolls are filed under musical instruments. Read the recommended use. If it is not wood or laminate on a floor, it is outside this job. The comparison is limited to the six floor listings that survived that check.
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)