Underlay for Hybrid Flooring: Do You Need It?

📖 6 min read

Short answer: Our hybrid flooring comes with underlay already attached. You don't need to buy it separately.

This is one of the most common questions we get asked – and the confusion is understandable. If you've installed laminate or engineered timber before, you're used to rolling out underlay as a separate step. Hybrid flooring works differently.

Let's clear up exactly what's built in, when that's enough, and the rare situations where you might need something extra.

What's already built into our hybrid flooring

Every plank in our hybrid flooring range has a minimum 1.5mm IXPE foam underlay factory-bonded to the bottom. IXPE (Irradiated Cross-linked Polyethylene) is a closed-cell foam – meaning it doesn't absorb moisture and won't compress or break down over time like cheaper foam underlays can.

Because it's pre-attached to each plank, there's no separate roll to buy, no cutting and taping, and no extra installation step. The planks click together and go straight onto your prepared subfloor.

This is one of the reasons hybrid flooring is faster and easier to install than laminate or engineered timber – the underlay is already done. For more on installation, see our guide on how to install hybrid flooring.

What the built-in underlay actually does

That 1.5mm layer isn't just padding. It serves four practical purposes:

1. Cushioning underfoot
Hybrid flooring has a rigid SPC (stone plastic composite) core – which is great for stability but can feel hard on its own. The foam layer adds just enough give to make it comfortable to stand on, especially in kitchens where you might be on your feet for a while.

2. Sound absorption
Without underlay, hard flooring can sound hollow and echoey when you walk on it. The foam layer dampens that "tap tap tap" sound, making footsteps quieter. It won't make your floor silent, but it takes the edge off. According to the Australasian Timber Flooring Association (ATFA), appropriate underlay is essential for acoustic performance in floating floor installations.

3. Minor subfloor correction
Small imperfections in your subfloor – tiny dips, bumps, or texture variations – get absorbed by the foam layer rather than telegraphing through to the surface. We're talking minor stuff here (1-2mm), not major levelling issues.

4. Moisture barrier
The closed-cell IXPE foam doesn't absorb water, so it acts as a barrier between your subfloor and the flooring above. This helps protect against minor moisture migration from concrete slabs – one of the reasons hybrid flooring performs so well in Brisbane's humid climate.

When the built-in underlay is enough (most of the time)

For the majority of residential installations, the attached 1.5mm IXPE underlay is all you need. This includes:

• Houses on concrete slabs – The foam provides adequate cushioning and moisture protection for standard slab installations
• Houses on timber subfloors – Works well over plywood or particle board subfloors
• Open-plan living areas – Handles normal household foot traffic comfortably
• Kitchens, bathrooms, laundries – The waterproof core plus foam underlay handles wet areas fine (see our guide to best flooring for kitchens)
• Bedrooms – More than adequate cushioning and sound absorption
• Single-storey homes – No upstairs neighbours to worry about
• Most freestanding houses – No body corporate acoustic requirements

If you're installing hybrid flooring in a regular house and your subfloor is in reasonable condition, you're good to go with what's already attached. Don't let anyone upsell you on extra underlay you don't need.

When you might need additional underlay

There are a few specific situations where adding a separate underlay underneath your hybrid flooring makes sense:

1. Apartments and townhouses with acoustic requirements

This is the most common reason people need extra underlay.

Many body corporates and strata schemes require flooring to meet specific acoustic ratings – usually expressed as an IIC (Impact Insulation Class) rating of 50 or higher. This measures how well the floor reduces impact noise (footsteps, dropped objects) travelling to the unit below.

The built-in 1.5mm underlay on its own typically won't meet IIC 50+ requirements. You'll need to add a separate acoustic underlay underneath – usually 2-3mm of specialised acoustic foam or rubber.

Before you order flooring for an apartment:

• Check your body corporate or strata rules for acoustic requirements
• Ask what IIC rating is required (usually IIC 50 or IIC 55)
• Factor in the cost of acoustic underlay ($8-15/m² for good quality)
• Make sure you get documentation for the combined floor system – some body corporates want proof

For more information on acoustic ratings and strata requirements, the NSW Fair Trading strata living guide provides useful background on common body corporate rules.

2. Concrete slabs with known moisture issues

While the IXPE underlay acts as a moisture barrier, it's designed for normal conditions – not active moisture problems.

If your concrete slab has a history of dampness, is below ground level (like a basement or lower-ground floor), or you're in a flood-prone area, some installers recommend an additional polyethylene moisture barrier (builder's plastic) underneath the hybrid flooring.

This is a precaution, not always necessary. A proper moisture test of your slab before installation will tell you whether it's needed. Australian Standard AS 1884 recommends concrete slabs have a relative humidity of 75% or less before installing flooring. Your installer should test this as part of standard subfloor preparation.

3. Very uneven subfloors

The built-in underlay handles minor imperfections – small dips and bumps up to about 1-2mm. Anything bigger than that needs to be fixed at the subfloor level, not covered up with thicker underlay.

If your subfloor has noticeable dips, high spots, or waves, you'll need to level it with self-levelling compound (for concrete) or sand down high spots (for timber) before installing. Trying to fix major unevenness with extra underlay doesn't work – you'll end up with a bouncy, unstable floor that wears unevenly.

The rule: Fix the subfloor first. Underlay is for comfort and sound, not for levelling. For more on this, see our subfloor preparation guide.

Types of additional underlay (if you need it)

If you do need to add extra underlay – usually for acoustic reasons in apartments – here are the main options:

Acoustic foam underlay

Cost: $5-10/m²
Thickness: 2-3mm
Best for: Apartments needing to meet IIC requirements on a budget

This is the most common choice for apartments. It's a denser, more specialised foam than basic underlay, designed specifically to reduce impact sound transmission. Look for products with tested IIC ratings – don't just trust marketing claims.

Rubber acoustic underlay

Cost: $10-20/m²
Thickness: 2-5mm
Best for: Apartments with strict acoustic requirements, or where maximum sound reduction is wanted

Rubber underlays generally perform better acoustically than foam, but they cost more and can be trickier to install. They're heavier and don't "give" as easily during installation. Worth it if your body corporate has strict requirements or you're particularly noise-conscious.

Cork underlay

Cost: $12-22/m²
Thickness: 2-6mm
Best for: Eco-conscious buyers, good all-round performance

Cork is a natural material with good acoustic and thermal properties. It's more expensive but appeals to people who want a more sustainable option. Make sure any cork underlay you use is compatible with hybrid flooring – some are designed for timber only.

Polyethylene moisture barrier

Cost: $2-5/m²
Thickness: 0.2mm (thin plastic sheet)
Best for: Additional moisture protection on concrete slabs

This is just builder's plastic – a thin polyethylene sheet laid over concrete before the flooring goes down. It's cheap insurance if you're worried about slab moisture, but it doesn't add cushioning or sound absorption. You'd use this in addition to the built-in underlay, not instead of it.

Common underlay mistakes to avoid

We've seen a few recurring mistakes when it comes to underlay decisions:

❌ Doubling up on underlay "for extra cushioning"

More underlay isn't always better. If you add thick foam underlay underneath hybrid flooring that already has underlay attached, the floor can feel too soft and bouncy. The click-lock joints work best on a firm base – too much give can stress the locking mechanism and cause issues over time.

If you need extra underlay (for acoustic reasons), stick to 2-3mm maximum on top of what's already built in.

❌ Using cheap, thin underlay to "save money"

Since our hybrid flooring already has quality underlay attached, you don't need to buy any underlay for most installations. But if you do need acoustic underlay for an apartment, don't cheap out on the thinnest option available – it probably won't meet your body corporate's requirements anyway, and you'll have to do it again.

❌ Using underlay designed for other flooring types

Underlay designed for carpet or solid timber isn't always suitable for hybrid flooring. Some products are too thick, too soft, or not compatible with floating floor installations. If you need additional underlay, make sure it's rated for use with rigid core/SPC/hybrid flooring. The ATFA resources page has technical guidance on underlay compatibility.

❌ Using underlay to fix a bad subfloor

We've said it already, but it's worth repeating: underlay is not a substitute for proper subfloor preparation. If your subfloor is uneven, damaged, or has moisture problems, fix those issues first. No amount of underlay will solve underlying problems.

❌ Removing the attached underlay

We've had people ask if they should peel off the built-in underlay before adding their own. No! The attached underlay is factory-bonded and designed to work with the plank. Removing it would damage the flooring and void any warranty. If you need extra underlay, add it underneath – don't try to replace what's already there.

Frequently asked questions

Do I need underlay for hybrid flooring?

Not usually. Our hybrid flooring comes with 1.5mm IXPE underlay pre-attached, which is sufficient for most residential installations. You only need additional underlay if your apartment has specific acoustic requirements, or in rare cases involving concrete moisture issues.

Can I install hybrid flooring without underlay?

You shouldn't install hybrid flooring without any underlay – but since ours has underlay built in, you don't need to buy it separately. The attached foam layer provides necessary cushioning, sound absorption, and moisture protection.

What underlay is best for hybrid flooring?

The best underlay for hybrid flooring is the one that's already attached. If you need additional underlay for acoustic reasons (apartments), look for 2-3mm acoustic foam or rubber underlay that's rated for use with SPC/rigid core flooring.

Does hybrid flooring need acoustic underlay?

Only if you're in an apartment or townhouse with body corporate acoustic requirements (usually IIC 50+). Freestanding houses generally don't need additional acoustic underlay – the built-in layer is adequate.

Can you put hybrid flooring directly on concrete?

Yes. Our hybrid flooring can go directly onto a concrete slab – the attached underlay acts as both cushioning and moisture barrier. Just make sure the slab is clean, dry, and level (within 3mm over 2 metres as per AS 1884). For slabs with known moisture issues, you might add a polyethylene sheet underneath as extra protection.

How thick should underlay be for hybrid flooring?

The built-in 1.5mm is designed to be optimal for the product. If adding extra underlay for acoustic purposes, 2-3mm is usually sufficient. Going thicker than that can make the floor feel unstable and stress the click-lock joints.

Is IXPE underlay better than EVA?

Yes, generally. IXPE (Irradiated Cross-linked Polyethylene) is a closed-cell foam that doesn't absorb moisture and maintains its structure over time. EVA (Ethylene Vinyl Acetate) is cheaper but can compress and break down faster. We use IXPE because it performs better long-term.

What's the difference between hybrid flooring and laminate underlay requirements?

Laminate flooring typically requires you to purchase and install underlay separately – it doesn't come pre-attached. Hybrid flooring has the underlay built in, which simplifies installation and ensures you have the right underlay for the product. This is one of several differences covered in our hybrid vs laminate comparison guide.

The bottom line

For most people, the underlay question is simple: you don't need to buy any. Our hybrid flooring comes with quality IXPE underlay already attached, and for standard residential installations – houses, townhouses, ground-floor apartments – that's all you need.

The main exception is apartments with body corporate acoustic requirements. If you're installing in a unit with neighbours below, check your strata rules for IIC ratings before you order. You may need to add a separate acoustic underlay to meet their requirements.

Not sure what applies to your situation? Give us a call on 0406 304 357 or send us a message. We're happy to talk through what you need – and more importantly, what you don't.

As members of the Australasian Timber Flooring Association (ATFA), we follow industry best practices and can point you to the right resources for your specific installation.

Last updated: December 2025 · Written by the team at Hybrid Floors Australia.

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