Laminate flooring gets most of the attention, but the underlay underneath it determines how the floor actually feels, sounds, and performs. Get this wrong and even a £30/m² laminate will sound hollow, feel bouncy, and develop clicking joints within a year. Get it right and a budget floor can feel like a premium one. The good news is that quality underlay costs surprisingly little — the mistake most people make is either skipping it entirely, using the wrong type, or buying whatever the retailer upsells them without understanding the specs.
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Key Takeaways
- 3mm combination (foam + film) underlay is the right choice for most UK laminate installations over concrete.
- If your laminate has pre-attached underlay, do not add a separate layer — it voids most manufacturer warranties.
- For underfloor heating, use a specialist UFH-compatible underlay with a tog rating of 0.5 or below.
- Rubber and felt underlays offer better acoustic performance than basic foam — worthwhile for flats and upper floors.
- Underlay costs £2–£8/m² — spending slightly more here pays dividends in comfort and noise reduction.
- Always check the laminate manufacturer’s specified underlay requirements before purchasing.
Why Underlay Actually Matters
Underlay serves three distinct functions in a laminate installation, and understanding them helps you choose the right product.
Sound insulation. Laminate flooring is essentially a floating layer of compressed fibreboard with a photographic layer on top. Without underlay, impact sound — footsteps, dropped objects, chair legs — transfers straight through the floor and into the room below. In a flat or a house with rooms above and below, this matters enormously. The acoustic performance of underlay is measured in decibels of impact sound reduction; better underlays reduce impact noise by 19–24dB.
Thermal insulation. A layer of underlay adds meaningful thermal resistance between a cold concrete subfloor and your living space. This is the tog rating you’ll see on underlay packaging. For most installations, a tog of 1.0–1.5 is appropriate. For underfloor heating, you want the opposite — a low tog rating (0.5 or below) so heat passes through efficiently.
Subfloor levelling. No concrete subfloor is perfectly flat. A layer of compressible underlay absorbs minor variations (up to about 2–3mm over 1m), preventing the floor from rocking on high spots and protecting the click-lock joints from stress fractures. This is why thicker isn’t always better — an underlay that’s too thick and soft creates too much flex, which puts strain on the joints rather than relieving it.
Types of Laminate Underlay Compared
There are four main types of laminate underlay sold in the UK, each with different performance profiles and price points.
| Type | Cost (£/m²) | Sound Reduction | UFH Compatible | Best For |
|---|---|---|---|---|
| Basic foam (polyethylene) | £1.50–£2.50 | Low (10–14dB) | Sometimes | Ground floor, tight budgets |
| Foam + DPM combination | £2–£4 | Medium (14–18dB) | Sometimes | Concrete subfloors, standard rooms |
| Rubber crumb | £4–£7 | High (18–22dB) | Usually yes | Flats, upper floors, acoustic priority |
| Felt / fibreboard | £5–£8 | High (19–24dB) | Some products | Upper floors, premium installations |
Basic Foam Underlay
White or blue polyethylene foam, typically 2–3mm thick. The cheapest option (around £1.50–£2.50/m²) and adequate for ground-floor installations where noise transmission to rooms below isn’t a concern. It provides basic thermal insulation and subfloor levelling. The main limitation is its modest acoustic performance and relatively short lifespan — foam compresses over time and can lose its cushioning effect within 5–7 years on a busy floor. For an inexpensive laminate in a low-traffic room, foam is fine. For anything else, spend a bit more.
Combination (Foam + DPM) Underlay
A step up from basic foam: a foam layer bonded to a polyethylene damp-proof membrane on the underside. The DPM layer is essential when laying over concrete, which always carries some residual moisture. Without a DPM, moisture vapour can migrate up through the subfloor and damage the laminate from below — causing swelling, edge lifting and mould growth in the worst cases. If you’re laying laminate over concrete at any level, use a combination underlay with integrated DPM. It costs only slightly more (£2–£4/m²) than foam alone and the protection it provides is worthwhile. Products like Duralay Standard and Leggett B&Q Combilay are widely available examples.
Rubber Crumb Underlay
Made from recycled rubber granules, rubber underlay is denser than foam and significantly better at absorbing impact sound. It’s the preferred choice for flats and first-floor installations where the neighbour below would otherwise hear every footstep. It’s also more dimensionally stable than foam — it doesn’t compress and thin over time. Many rubber underlays are compatible with underfloor heating systems; check the manufacturer’s tog rating. Expect to pay £4–£7/m². Duralay Heatstore, Leggett Acoustilay, and Regupol are well-regarded UK options.
Felt / Fibreboard Underlay
Made from compressed recycled textile fibres. Felt underlay is the most luxurious-feeling option — boards feel solid and reassuringly firm underfoot rather than bouncy. It has excellent acoustic performance and a long lifespan. The premium cost (£5–£8/m²) is justified in high-spec installations. Acoustilay Gold, Tredaire Extrafelt and Duralay Premier are reliable UK products. Not all felt underlays are suitable for UFH, so check the specification.
Pre-Attached Underlay: When Not to Add More
Many laminate boards now come with a thin foam or felt layer pre-attached to the underside of each plank. This is convenient and cuts installation time, but it creates an important rule: do not lay a separate underlay beneath boards that already have one attached. Doubling up the underlay creates too much flex in the floating floor, putting excessive strain on the click-lock joints and leading to premature failure. Nearly every laminate manufacturer voids their warranty if the installer uses separate underlay over boards with pre-attached backing.
If your boards have pre-attached underlay and you’re laying over concrete, you still need a DPM — but use a standalone polythene damp-proof membrane (not an underlay with DPM), which adds minimal thickness. 0.2mm polythene sheeting costs around £0.50/m² and is available from any builders’ merchant.
Underlay for Underfloor Heating: Different Rules Apply
Underfloor heating and laminate flooring is a combination that requires careful specification. The key concern is thermal resistance: a thick, insulating underlay that’s great for a cold concrete floor actively impedes the heat output of a UFH system, making it less efficient and slower to respond.
For UFH installations, you need a specialist underlay with a tog value of 0.5 or below. Most laminate manufacturers specify a maximum combined tog (underlay plus board) of 1.5 for UFH compatibility — and many laminate boards themselves have a tog of 0.5–1.0, leaving little headroom for underlay.
Good UFH-compatible underlay options include: Duralay Heatstore (rubber crumb, 3mm, 0.5 tog), Leggett UFH Underlay, and Robina UFH Underlay. Always confirm both the underlay tog and the board tog before committing. Our guide to underfloor heating compatible flooring covers the full picture, including which board types work best with UFH.
The Flooring Group’s guidance on UFH and laminate is a useful technical reference, as is the Which? laminate flooring guide for broader product testing data.
How Thick Should Laminate Underlay Be?
For most laminate installations, 3mm is the sweet spot. It provides adequate cushioning, decent acoustic performance and acceptable subfloor levelling without creating too much flex. Thicker underlays (5mm+) are sometimes marketed as premium options, but for laminate flooring they can cause more problems than they solve — the additional bounce stresses click joints and can cause gaps to appear over time.
The laminate floor itself also needs to be properly flat — underlay is not a substitute for subfloor preparation. The subfloor should be within 3mm over 1.8m before underlay goes down. Any greater variation needs to be addressed with self-levelling compound first. No amount of underlay compensates for a badly prepared subfloor. See our full guide to best laminate flooring UK for board specifications and brand recommendations.
Our Top Recommendations
For most homes with a concrete subfloor: a 3mm foam + DPM combination underlay in the £2–£4/m² range is the practical choice. Duralay Standard or Leggett Combilay are both widely available and reliable. For flats or first-floor rooms where noise is a concern: step up to a 3mm rubber crumb underlay like Duralay Heatstore or Regupol — the extra £2–£4/m² makes a meaningful difference to impact noise. For UFH: use a specialist UFH underlay and keep the combined tog under 1.5. Don’t use whatever’s cheapest, and don’t double up if your boards already have underlay attached. That’s really all there is to it.
For guidance on your legal rights if a flooring product causes problems, see the Consumer Rights Act 2015 on gov.uk.