Best Underlay for Carpet: What Underlay Do I Need Under My New Carpet in Peterborough?

The best underlay for carpet in most rooms is a 9–11mm PU foam. It is warm, soft and supportive, and costs £4–£6/m² supplied and fitted in Peterborough. Stairs and hallways need a denser PU foam or crumb rubber, at £6–£8/m². Standard underlay is already included in our carpet prices, so you only pay more if you upgrade.

Room by room: For most Peterborough homes, a 9–11mm PU foam underlay in a dense grade is the best choice for living rooms and bedrooms. For stairs, use a firmer, denser underlay (dense PU foam or crumb rubber, 8–10mm) to maintain carpet edge definition. For concrete subfloors — common in Peterborough bungalows and new builds — always use a damp-proof membrane underlay to prevent moisture transfer.

Most Peterborough homeowners focus on choosing the right carpet — and give almost no thought to the underlay underneath it. This is a mistake. Underlay affects how your carpet looks, how long it lasts, how warm the room feels, and how well sound is absorbed between floors. The wrong underlay can cut years off a quality carpet’s lifespan; the right underlay makes even a mid-range carpet feel considerably more luxurious.

Our carpet underlay supply and fitting service covers the whole of Peterborough — PE1, PE2, PE3, PE4, PE6, PE7 — and this guide explains everything you need to know before choosing.

What Is the Best Underlay for Carpet?

For most rooms it is a quality PU foam, 9–11mm thick. It gives the best balance of comfort, warmth and support for the money, which is why it is the underlay we fit most often in living rooms, bedrooms and on landings. The exceptions are stairs and hallways, which need something firmer, and rooms where noise from above or underfloor heating changes the answer. This is how the main grades compare:

Every figure is supplied and fitted by our own team. Underlay starts from £4/m², and a standard underlay is already included in our carpet prices, which start from £14/m² with underlay and gripper. Premium comfort and acoustic grades are optional and quoted as a separate line. The full list is on our carpet prices in Peterborough page, and the carpets themselves are on our carpets in Peterborough page.

Why Does Underlay Matter?

Carpet underlay serves four distinct functions. First, it acts as a cushion — absorbing the impact of foot traffic and preventing the carpet pile from being driven hard into the subfloor on every step. Without underlay, carpet pile compresses and flattens much more quickly, particularly in walkways and in front of sofas and chairs where people pivot their feet repeatedly.

Second, underlay provides thermal insulation. Particularly important in Peterborough’s older housing stock — the Victorian and Edwardian terraces of PE1 and PE2, the post-war bungalows of PE3, and the 1970s and 1980s estates of Bretton and Orton — a good underlay adds meaningful warmth to rooms with concrete or suspended timber subfloors.

Third, underlay provides acoustic insulation — reducing impact sound transmission between floors. This matters most in upstairs bedrooms and in multi-storey Peterborough homes where footfall noise from upper floors carries to the rooms below.

Fourth, a quality underlay extends carpet life. The additional cushioning reduces pile fatigue, and on timber subfloors, the underlay bridges minor gaps and undulations in the boards that would otherwise create uneven wear patterns across the carpet surface.

Types of Carpet Underlay We Fit in Peterborough

PU Foam Underlay

PU (polyurethane) foam is the most commonly fitted underlay across Peterborough homes. It’s available in a wide range of thicknesses (typically 8–12mm) and densities, and offers the best cushioning performance per pound of any underlay type. The key performance metric is density, not thickness — a denser foam at 11mm will outperform a softer foam at 12mm and will resist compression far longer under furniture. Density is measured in kg/m³ and printed on the label, so two underlays of the same thickness can be compared directly. We recommend a 9–11mm PU foam in a dense grade for living rooms and bedrooms in Peterborough homes; quality PU foam is £4–£6/m² supplied and fitted.

Rubber Underlay

Rubber (crumb rubber) underlay is denser and firmer than PU foam. It’s the preferred choice for stairs across Peterborough, where the added firmness helps the carpet maintain a crisp edge on each step nose. Rubber underlay also has excellent durability — it doesn’t compress or degrade over time the way softer foam does — and is a good choice for hallways where a more solid feel underfoot is preferred. It costs slightly more than PU foam: dense crumb rubber is £6–£8/m² supplied and fitted. Sponge rubber is the traditional alternative, dense and very hard-wearing, and suits the same heavy-traffic areas. Our stair carpet in Peterborough page covers how stairs are fitted and priced, from £25 per step.

Acoustic Underlay

Acoustic underlay is a dense, premium grade made to cut impact noise — the footfall you hear in the room below. It earns its place in bedrooms above living rooms, in flats and in upstairs rooms of rental properties, where a standard foam is comfortable but lets more sound through. Premium acoustic grades are £6–£8/m² supplied and fitted. We bring underlay samples to the home visit so you can feel the difference before you choose.

Felt Underlay

Wool or synthetic felt underlay offers very high thermal insulation and is the traditional choice for period properties in PE1 and PE2 where natural materials are preferred. It has a firmer, more traditional feel than PU foam and is well-suited to wool carpets from brands like Ulster or Westex where a natural fibre pairing is desirable. Felt underlay is less commonly fitted today than foam or rubber but remains an excellent product when specified correctly.

Which Thickness and Density for Different Rooms?

• Living rooms and bedrooms: 9–11mm PU foam in a dense grade. Upgrade to a denser, premium underlay for premium carpets from Westex or Ulster.
• Hallways: 10mm PU foam or rubber underlay — firmer feel, better durability at turning points and near doors.
• Stairs: 8–10mm crumb rubber or high-density PU foam. A deep, soft underlay on stairs lets the carpet move at the step edges, which wears it faster and can be a trip hazard.
• Bedrooms with UFH (underfloor heating): Combined tog rating of carpet + underlay should usually be 2.5 or below. Use a thin, dense, low-tog underlay made for underfloor heating.

Is Thicker Underlay Always Better?

No. Thickness adds softness, but density is what stops an underlay flattening, so a dense 9–11mm underlay will outlast a softer, thicker one. Too thick an underlay under a heavy carpet can feel unstable, and on stairs it lets the carpet move on the step edges. Thickness also raises the finished floor, so with a deeper grade we check that the doors still clear; door trimming, where it is needed, is quoted as a separate line.

Underlay for Concrete Subfloors in Peterborough

Concrete subfloors are the norm in post-war bungalows and 1950s–1980s housing across Peterborough — particularly in Dogsthorpe (PE1), Paston (PE4), and the Orton and Bretton estates (PE2 and PE3). Concrete subfloors can transmit ground moisture, which is absorbed by carpet backing and underlay over time, causing musty smells, mould growth, and premature carpet deterioration.

For any concrete subfloor, we always recommend a damp-proof membrane underlay — a foam or rubber underlay with an integrated foil or polythene vapour barrier. This is the single most important underlay specification decision for Peterborough homes with solid ground floors. Without it, a quality carpet installed on a concrete floor can develop moisture-related issues within a few years, regardless of how good the carpet itself is.

What Underlay Do You Need Over Underfloor Heating?

A thin, dense, low-tog underlay made for underfloor heating, so the heat passes into the room instead of being held under the carpet. The carpet and underlay together should usually stay at 2.5 tog or below, and the heating manufacturer's limit has the final say. A deep comfort underlay can use up most or all of that allowance on its own. Underfloor heating is common in newer Peterborough homes in Hampton and Cardea, so we ask about it at every home visit before recommending an underlay.

Can You Use Carpet Underlay Under Laminate or LVT?

No. Carpet underlay is too soft for a floating floor: the boards move, the floor sounds hollow and the joints wear early. Under laminate flooring in Peterborough homes we fit a thin, firm acoustic underlay, often with an integral damp-proof membrane over concrete, and it is included in our laminate prices.

Underlay Brands We Use in Peterborough

We specify and fit underlay from leading manufacturers including:

• Duralay — a British-made underlay brand, best known for dense crumb rubber and sponge rubber grades of the kind we use on stairs and in hallways.
• Ball & Young Cloud 9 — a premium PU foam underlay for homeowners who want the best possible cushioning performance. Available in several thicknesses and densities.
• Tredaire — a well-known name in PU foam and rubber underlay. The Tredaire Dreamwalk, an 11mm PU foam, is a popular premium choice for carpets in formal living rooms and master bedrooms.

Standard underlay is included in our carpet prices, and any upgrade is itemised in the written quote that follows your free home visit. We don’t charge separately for underlay selection advice — it’s part of the service.

How Much Does Underlay Cost in Peterborough?

As a guide, carpet underlay costs from £4/m² supplied and fitted, depending on type and specification: £4–£6/m² for quality PU foam and £6–£8/m² for dense crumb rubber and premium acoustic grades. Standard underlay is already included in our carpet prices, so on a carpet quote you only pay more if you upgrade, and the upgrade is shown as its own line. The full list for every floor type is on our flooring prices in Peterborough page. For a full carpet fitting quote including underlay for your Peterborough home, call us on 01733 924009.

Book a Free Home Visit for Carpet Underlay Advice

The quickest way to choose an underlay is to stand on the samples. As carpet fitters in Peterborough, we bring carpet and underlay samples to your home, check the subfloor, measure up and send a written quote within 24 hours, with the underlay itemised. Every floor is fitted by our own team and backed by a 2-year workmanship guarantee. You can also see samples at our showroom at 4 The Manor Grove Centre, Vicarage Farm Road, Peterborough PE1 5UH, and we fit in every Peterborough neighbourhood. Call 01733 924009 to book your free home visit with samples, Monday to Friday, 9am–5pm.