Written by the Carpet Flooring Supplies team
Practical buying guidance based on current manufacturer specifications and our experience supplying carpet underlay nationwide.
The best carpet underlay for reducing noise is one that suits your carpet and room, with relevant impact-sound test results to support its performance. Start with the noise you want to reduce, then compare the specifications of suitable products.
“Soundproof underlay” is a common search term, but it can create the wrong expectation. Carpet and underlay can cushion footsteps and other impacts. They cannot guarantee silence, stop every noise from the room below or repair weaknesses elsewhere in the building.
What kind of noise are you trying to reduce?
Impact sound starts with contact against the floor: footsteps, a chair being moved or a toy dropped upstairs. That contact sends vibration into the structure. A resilient underlay beneath carpet helps cushion it before the vibration travels further.
Airborne sound starts in the air, such as conversation, music or a television. It can travel through the floor, walls, gaps and connected parts of the building. Changing the underlay may form part of a wider improvement, but its impact-sound figure does not measure how much speech it will block.
If your main concern is footfall from a bedroom above a lounge, carpet underlay is relevant. If you hear clear conversations through a party wall, investigate that sound path before choosing a different roll. ROCKWOOL's acoustic guidance explains why sound passing around a separating surface also matters.
What does an underlay's dB rating mean?
Look for a defined measure such as impact sound reduction, ΔLw, or an impact sound improvement index on the manufacturer's technical sheet. The number describes a result obtained under stated test conditions. For comparable improvement figures, a larger number means greater measured improvement.
A 43dB figure does not promise that every noise in your house will become 43dB quieter. The carpet, structural floor, ceiling, installation and surrounding construction influence what you hear. A laboratory improvement figure is also different from a measurement of the complete floor in your home.
Before ranking two products, check that the figures use the same type of measure and a comparable test basis. Ask for clarification if the test construction or conditions are unclear. A small difference between catalogue numbers is a poor reason to ignore an important requirement such as carpet support or heating compatibility.
Examples of published acoustic figures
These are manufacturer-published examples from products listed by Carpet Flooring Supplies, checked in September 2026. They illustrate different priorities and are not a like-for-like laboratory trial conducted by us.
On a small screen, scroll the comparison table sideways.
| Product | Material and thickness | Published impact-sound figure | Thermal resistance |
|---|---|---|---|
| Cloud 9 Cumulus | PU foam, 11mm | 43dB | 3.1 tog |
| Cloud 9 Cirrus | PU foam, 9mm | 39–41dB | 2.6 tog |
| Tredaire Chromium | PU foam, 9mm | 42dB | 2.26 tog |
| Tredaire Treadmore | Crumb rubber, 7.95mm | 32dB | 1.03 tog |
| Duralay Heatflow Carpet | Sponge rubber, 6.1mm | 31dB | 0.75 tog |
The current Cumulus and Cirrus technical sheets report an impact sound improvement index. The Chromium, Treadmore and Heatflow Carpet sheets report ΔLw. They cite different test editions, so the table should not be read as proof that closely spaced numbers will produce an audible difference in your home.
Cirrus is shown as the manufacturer's 39–41dB range; some retail listings use a single figure. For Treadmore, the table uses Interfloor's 1.03 tog. Confirm the exact product specification if a small difference affects your purchase.
Choose acoustic underlay for the room
Bedrooms and lounges
For an unheated bedroom or lounge, a cushioned domestic underlay with useful impact-sound performance can be a sensible starting point. Cumulus and Cirrus are comfort-focused examples. Chromium provides another PU option, with a heavy-contract classification. Check the carpet manufacturer's requirements and the available height at doors and thresholds before deciding.
Stairs and landings
Repeated traffic and support around stair edges matter alongside noise. Treadmore has an explicit manufacturer recommendation for stairs, landings and heavy-use areas. Its lower published acoustic figure does not make it an inferior choice for a staircase where firm support is the main requirement.
Our stairs and hallways guide explains what to check before choosing a stair underlay.
Rooms with underfloor heating
First find a product approved for the heating system. A high tog means more resistance to heat passing through the floor, which can conflict with heating requirements. Calculate the combined thermal resistance of the carpet, underlay and any required overlay, then compare it with the system manufacturer's limit.
Heatflow Carpet combines a low 0.75 tog with a published 31dB impact-sound result. Its manufacturer does not recommend it for electric mat or dry underfloor-heating systems. Read our underfloor-heating underlay guide and confirm the complete installation before ordering.
Flats and floors between separate homes
If the project has an acoustic specification or requires approval from a landlord or freeholder, establish those requirements before buying. An underlay's dB figure alone does not demonstrate the performance of the complete floor. For a persistent noise problem, an acoustic specialist can identify whether the main route is through the floor or around it.
Is thicker underlay always quieter?
Thickness and resilience can help cushion footfall, as Interfloor's impact-sound guidance explains. However, thickness is not a substitute for a relevant acoustic result or a suitable use classification.
A deeper product may introduce extra height at a doorway, too much thermal resistance over heating or a feel that does not suit the carpet. Dense rubber and PU foam can both offer useful acoustic performance. Compare named products rather than assuming that one material or thickness wins every time.
Read our underlay thickness comparison and PU foam versus rubber guide for the other parts of that decision.
Floor condition and fitting still matter
Underlay is not a repair for a loose, uneven or damaged floor. Ask your fitter to assess the subfloor and investigate squeaks before the new carpet goes down. Any work around pipes, cables or floor penetrations needs an appropriate installation detail.
The underlay must suit the fitting method as well as the carpet. Interfloor's installation guidance distinguishes stretch-fit and double-stick methods and calls for secured underlay seams. Follow the instructions for the products being fitted; overlapping sheets or adding an unapproved second layer is not a soundproofing plan.
A practical buying checklist
- Identify whether footsteps and impacts, airborne noise or both are the concern.
- Confirm carpet compatibility, room suitability, fitting method and heating requirements.
- Compare relevant acoustic figures and their test basis within that shortlist.
- Check finished floor height, roll quantity and total delivered cost.
- Have the floor condition and installation assessed before fitting.
Carpet Flooring Supplies sells online for nationwide delivery on a supply-only basis. Arrange measuring and fitting separately, and check current product availability and delivery details before booking the work.
Frequently asked questions
Will carpet underlay soundproof a room?
It can reduce impact noise through a carpeted floor, but it cannot guarantee complete soundproofing. Voices, music and sound travelling through other parts of the building may need a wider solution.
What dB rating should I look for?
Start with the right type of test result and a product suitable for the room. Compare improvement figures on the same basis. A larger headline number is not a guarantee of a particular result in your building.
Is foam or rubber underlay better for noise?
Both can be useful. Foam includes products with high published impact-sound figures; rubber includes firm-support and low-tog options. Use the exact specifications and intended application to choose.
Will new underlay stop voices from downstairs?
Do not rely on its impact-sound rating for that job. Speech is airborne sound, and the floor, ceiling and surrounding sound paths need to be considered together.
Can I fit two layers of underlay for extra noise reduction?
Use only an installation approved by the carpet and underlay manufacturers. Doubling ordinary underlay does not provide a verified acoustic result and can change the carpet's support and finished height.
Can I get acoustic underlay for a heated floor?
Yes, but heating compatibility and the complete floor's thermal limit come first. Compare acoustic performance among the products that meet those requirements, including any restrictions on the type of heating system.