Carpet underlay buying guide
Updated: October 2026
You are measuring a room before the carpet arrives, and the amazon.co.uk titles are a wall of 8 mm, 10 mm and 12 mm foam. A carpet underlay buying guide for this set starts with the job, then the material you can name, then whether the thickness clears the doors, then whether one roll covers the floor. Price and stars come after that. None of the eleven listings prints a BS EN 14499 end-use class, so a stair sentence on a bullet is not a class code. The full table is the [carpet underlay comparison](/hub/flooring/carpet-underlay). A shortlist by room is [best carpet underlay](/hub/flooring/carpet-underlay/sub/carpet-underlay-best). Products Compared read these listings on 19 October 2026. We did not test them in a lab.
You are measuring a room before the carpet arrives, and the amazon.co.uk titles are a wall of 8 mm, 10 mm and 12 mm foam.
You are measuring a room before the carpet arrives, and the amazon.co.uk titles are a wall of 8 mm, 10 mm and 12 mm foam. A carpet underlay buying guide for this set starts with the job, then the material you can name, then whether the thickness clears the doors, then whether one roll covers the floor. Price and stars come after that. None of the eleven listings prints a BS EN 14499 end-use class, so a stair sentence on a bullet is not a class code. The full table is the carpet underlay comparison. A shortlist by room is best carpet underlay. Products Compared read these listings on 19 October 2026. We did not test them in a lab.
Our top picks
| Badge | Product | Thickness | Coverage | Material | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  FloorPro FloorPro 10 mm 5 m² | 10 mm | 5 m² | PU foam | 9.6 | about £27.50 | View offer |
| Best value |  SIXNEA SIXNEA 12 mm PU underlay | 12 mm | 15 m² | PU recycled foam | 9.4 | about £48.99 | View offer |
| Alternative |  247Floors 247Floors PU foam 10 mm | 10 mm | 15.07 m² | PU foam | 9.4 | about £54.95 | View offer |
On this page
Start with the room, not the millimetres
A cold bedroom, a hallway and a stair flight are different orders. In a bedroom you are mostly buying cushion, and a light polyurethane roll is the domestic default in this basket. In a hall the sheet takes more traffic and furniture. On stairs, trade guides want a firmer underlay and a class that allows stairs. Floorwise’s short codes include LD/U for light domestic use, and that code is not for stairs. GD/U, L/U and HC/U are other intended-use marks. None of them appears on these eleven pages.
Published thickness maps disagree, which is why a millimetre slogan is a weak first step. Carpetshire’s room table puts bedrooms around 10–11 mm and halls and stairs around 8–9 mm, and it treats heating as a tog question. Homebuilding’s comfort map runs the other way: about 8 mm for low traffic, 10 mm for general use, and 12 mm where you want more cushion. Hold both maps, then look at your own doors. A 12 mm roll in a bedroom is reasonable only if the door still clears the carpet.
The rolls you can name here are mostly polyurethane, including recycled PU on the SIXNEA sheet. FloorPro’s £25.99 roll is polyethylene, with a 7 mm title and a 6 mm catalogue line. Plushwalk is sold as 12 mm memory foam. Crumb rubber and sponge rubber are not in the basket. That material split is PU foam vs rubber carpet underlay.
Thickness is a door and nosing check
Thicker is not a quality score. Carpetshire’s reason for stopping near a common manufacturer cap of about 11 mm is practical: door clearance, carpet movement, and a sheet soft enough to let the carpet shift. A 12 mm foam under a door that already brushes the pile will force you to plane the door or live with a scrape. On a stair nosing, a very soft thick foam can leave the carpet feeling loose even when the gripper is right. Stair guides talk about density bands, such as under 90 kg/m³ for low traffic or about 100–120 kg/m³ as a residential stair range. Do not copy those numbers onto these ASINs. Density is not on the listings.
The FloorPro 8 mm roll is about £25.95 for 5 m² and the 10 mm roll is about £27.50 for the same 5 m². Both titles say they are suitable for stairs. That line is seller text. BS EN 14499:2024 is the current classification, with seven intended-use classes, and it supersedes the 2015 edition. These pages do not print a class from either edition. One buyer of the 8 mm roll wrote that 10 mm might have been better in their case, which is a feel comment, not a laboratory result.
The 12 mm group will feel deeper underfoot in reviews. One Flooring Online review says the grippers were raised by 10 mm so the extra thickness would sit inside them. If your grippers are already fixed and you cannot raise them, 12 mm is the wrong comfort upgrade. Heating is a separate limit, covered on carpet underlay for underfloor heating, because a thick cold-room roll can block the pipes.
Coverage, width, and the extra bits
Measure the floor, add cutting waste, then see whether one roll still covers it. TradeCalculator’s worked example is a 4 m by 3.5 m room, which is 14 m². Five percent waste stays inside a 15.07 m² roll, the 1.37 m by 11 m size. Ten percent tips you over that roll and into a second one. Most of the large rolls here are about 15 m². 247Floors states 15.07 m². Grandismo is 10 m², at 1.37 m by 7.3 m. The two FloorPro polyurethane rolls, and Flooring Online’s smaller red roll, are 5 m².
Width changes the seams. About 1.37 m is the usual fitted-carpet width, so a 3.5 m room needs three widths and a strip of offcut. A 1 m roll, which is what the FloorPro sheets are, needs more joins across the same room. More joins mean more tape, and a ridge if you overlap instead of butting the edges. Joining tape and gripper rods are not in this comparison. The polyethylene bullets name Barrier Pro X tape and do not say it is included.
Price per square metre is arithmetic on the 19 October 2026 shelf prices, not a quote for your postcode. The polyethylene roll is about £1.73/m². The FloorPro PU rolls are about £5.19 to £5.50/m² because they cover only 5 m². Most 10–15 m² foam rolls land about £3.27 to £3.95/m². Flooring Online’s 5 m² 12 mm roll and the Plushwalk roll are both about £8.00/m². Catalogue weights near 1 kg on Royale, the small Flooring Online roll and Plushwalk conflict with the roll size, so do not use those cells as the weight you will carry upstairs.
What a missing class actually means
A missing class means you cannot tell, from the page, whether the roll is light domestic, general domestic, or a stair grade. You can still buy it for a bedroom if the thickness, the coverage and the material line make sense. You should not treat “stairs” or “hard wearing” as the class you did not get. SIXNEA’s title says UK manufactured. That is a title claim, not a factory audit in this file. The star line, 4.7 from 1,686, is the largest sample here, and it is still not a wear test. The polyethylene roll is 3.9 from 83. The two Flooring Online ASINs share one review text and both show 4.6 from 422, so those counts are one sample printed twice.
“Tested to BS 5808:1991” on the Plushwalk bullets is the older British Standard that some Amazon listings still quote. It is not a current BS EN 14499 end-use class, and the bullet does not give a class code even under the old line. Plushwalk also prints a seller figure of 3.5 tog and 49 dB. Those are seller claims. A decibel figure is not a substitute for a class, and it is not Approved Document E evidence for a flat. If the class check fails for your stairs, or the tog is missing on a heated floor, stop and use a listing that prints the number you need.
Which check comes first
If the room is an unheated bedroom and the door clears, choose thickness and coverage before the ticket price. If the flight needs a stair class, leave this set, because none of the eleven pages prints one. If the grippers are already fixed, a 12 mm roll is the wrong upgrade. If the floor is heated, the next check is tog, not millimetres. A qualifying purchase through our links can earn a commission at no extra cost to you.
Common questions
What thickness should I buy for a bedroom, a hallway, and the stairs?
For a bedroom in this set, 10 mm or 12 mm polyurethane is the cushion people are buying, provided the door still clears. Halls and stairs are where the maps split: one trade table prefers about 8–9 mm and a firmer sheet, and another comfort map treats 12 mm as the busier-room choice. This basket does not print a stair class, so a hallway or a flight is not settled by thickness alone.
Is 12 mm automatically better than 10 mm or 8 mm?
No. Twelve millimetres is more cushion, and reviews of these rolls often like that feel. It also raises the floor. One shared Flooring Online review describes grippers lifted by 10 mm. Eight millimetres on the FloorPro 5 m² roll is a smaller stack, and one buyer still wished they had chosen 10 mm. Match the gap under the door, not a bigger number on the title.
How many square metres do I need, and do I add waste?
Multiply length by width, then add about 5–10 percent for cuts. A 4 m by 3.5 m room is 14 m². Five percent still fits a 15.07 m² roll. Ten percent does not, so you would be buying two rolls. A 5 m² roll only suits a box room, a landing, or a short run where the offcut from 15 m² would be most of the roll.
Why are some rolls 1 m wide and others about 1.37 m?
About 1.37 m is the usual fitted-carpet width, used by 247Floors, SIXNEA, Royale, SnugStep, Grandismo, Plushwalk and the Flooring Online rolls. The FloorPro sheets are 1 m wide. A narrower roll means more seams across a normal room, and each seam needs tape you buy separately. The 1 m width is not a defect. It is a cutting plan you should make before you order.
What does a missing BS EN 14499 class mean on the listing?
It means the page does not say which of the seven intended-use classes the roll was made for. Light domestic, LD/U in Floorwise’s shorthand, is not a stair grade. You can still use an unclassified foam in a low-traffic bedroom if the other checks pass. You cannot prove a stair or contract use from these bullets.
Is “tested to BS 5808” the same as a current end-use class?
No. BS 5808:1991 is the older standard. BS EN 14499:2024 is the current classification. Plushwalk’s bullet mentions a test to BS 5808 and does not print a class code. The other ten listings do not mention either standard’s class. A test name without a class still leaves the stair question open.
Why is a cheap 15 m² roll not the same bargain as a small roll?
Divide the shelf price by the stated square metres. FloorPro’s polyethylene sheet is about £1.73/m², and it is a different material from the PU rolls, with a thickness the listing does not agree on. The 5 m² polyurethane rolls cost more per square metre than the 15 m² foams near £3.30 to £3.95, even when the ticket price looks similar. Compare the rate, then check the material line.
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.
- BEAMA underfloor-heating guide — floor covering and the 2.5 tog combined limit (retrieved 19 October 2026)
- Nu-Heat — carpet and underfloor heating (retrieved 19 October 2026)
- Approved Document E — resistance to the passage of sound (retrieved 19 October 2026)
- NBS — BS EN 14499:2024 textile floor coverings, classification of carpet underlays (retrieved 19 October 2026)
- Floorwise recommendation guide — end-use class labels (retrieved 19 October 2026)
- Interfloor Omega 10 specification — example PU underlay (retrieved 19 October 2026)
- Carpetshire — thickness by room as a rule of thumb (retrieved 19 October 2026)
- Homebuilding — 8 mm, 10 mm, and 12 mm comfort map (retrieved 19 October 2026)