Hybrid Flooring Sydney: Extra Underlay With Attached Pads?

Adding extra underlay beneath hybrid flooring with an attached pad is only appropriate when the manufacturer permits the exact flooring and underlay combination. Some products, including Quick-Step Hybrid Vinyl Ciro, prohibit additional underlay. Godfrey Hirst documents a specific approved acoustic system. For Sydney homes and NSW apartments, product compatibility must be confirmed before purchasing materials. Extra cushioning cannot correct an uneven subfloor or replace proper floor preparation.

ELYMENT Insights | Flooring Installation & Renovation | Sydney, NSW | 4 November 2026

When More Underlay Becomes a Flooring Specification Problem

A hybrid flooring product with an attached acoustic pad can appear to offer the best of both worlds: a durable surface with an integrated layer intended to support the floor and contribute to acoustic performance.

For Sydney homeowners and renovation contractors, the temptation is straightforward. If one underlay helps, would another layer make the floor quieter or more comfortable?

That assumption overlooks an important feature of modern floating flooring systems.

The plank, its locking mechanism, its attached backing and the supporting substrate are designed to function together. Adding another material underneath changes the conditions under which that system operates.

In some cases, the manufacturer expressly prohibits the additional layer. In others, a particular acoustic underlay has been tested and permitted subject to installation conditions.

The distinction becomes especially important when flooring is ordered separately from the acoustic underlay, or when a builder substitutes one product for another during procurement.

The relevant question is not whether additional underlay can physically fit beneath the boards. It is whether the complete assembly is approved for that particular product.

Quick-Step and Godfrey Hirst Demonstrate Why Product Rules Matter

Two Australian manufacturer instruction sets illustrate why there is no reliable industry-wide answer to the extra-underlay question.

Quick-Step: An Integrated Pad Does Not Permit Another Layer

Quick-Step's May 2025 installation instructions for its Hybrid Vinyl Ciro product explicitly prohibit installing a separate underlay beneath the flooring.

The product already includes an integrated backing, and the manufacturer does not allow another underlay to be placed beneath the boards.

This requirement is not merely a recommendation to avoid unnecessary expenditure.

The instructions also warn that using accessories other than suitable Quick-Step Vinyl accessories may damage the flooring and invalidate the manufacturer's guarantee.

For an installer working with this product, adding generic foam or rubber underlay is therefore inconsistent with the published installation requirements.

The relevant technical reference is the Quick-Step Hybrid Vinyl Ciro installation instructions.

Godfrey Hirst: A Specific Tested Acoustic Assembly Is Permitted

Godfrey Hirst provides a contrasting example through its published instructions for installing hybrid flooring over Damtec acoustic underlay.

The August 2025 guidance states that Godfrey Hirst hybrid flooring may be installed over Damtec Rubber 910 2 mm, provided the specified conditions are followed.

The documented assembly includes:

1. Damtec Rubber 910 2 mm acoustic underlay, loose laid over a correctly prepared substrate.
2. A 200-micron builder's plastic layer installed over the Damtec underlay.
3. Godfrey Hirst hybrid flooring installed according to the applicable floating-floor installation instructions.

The underlay must also be installed according to the manufacturer's handling, orientation and acclimatisation requirements.

Importantly, Godfrey Hirst states that it cannot guarantee the performance of installations using other acoustic underlays.

This is permission for a defined system, not an unrestricted endorsement of double underlay beneath every hybrid plank.

The instructions are available in the Godfrey Hirst hybrid flooring over Damtec acoustic underlay technical document.

Before applying this specification to a particular product with an attached pad, the supplier or manufacturer should confirm that the exact product SKU and proposed build-up are covered by the current instructions.

Two Manufacturers, Two Different Installation Decisions

Additional Underlay

• Quick-Step Hybrid Vinyl Ciro: Separate underlay prohibited.
• Godfrey Hirst Hybrid: Specific Damtec Rubber 910 2 mm system permitted subject to instructions.

Manufacturer Position

• Quick-Step Hybrid Vinyl Ciro: Integrated underlay is part of the flooring system.
• Godfrey Hirst Hybrid: Documented additional acoustic assembly has been tested.

Alternative Acoustic Products

• Quick-Step Hybrid Vinyl Ciro: No separate underlay permitted under the cited instructions.
• Godfrey Hirst Hybrid: Performance with other acoustic underlays is not guaranteed.

Additional Layer Requirements

• Quick-Step Hybrid Vinyl Ciro: Follow the product's separate moisture-management requirements where applicable.
• Godfrey Hirst Hybrid: Specified assembly includes 200-micron builder's plastic over Damtec Rubber 910.

Procurement Decision

• Quick-Step Hybrid Vinyl Ciro: Do not order an additional cushioning underlay.
• Godfrey Hirst Hybrid: Confirm the exact flooring SKU, specified underlay and approved installation arrangement.

Comparison based on the identified manufacturer documents. Installation instructions can change, and the current requirements for the exact product take precedence.

Why Extra Cushioning Can Put Click-Lock Joints Under Pressure

Floating hybrid flooring relies on the substrate providing appropriate support across the floor.

The individual boards connect through engineered locking profiles designed to keep adjacent planks engaged while allowing the floor to move as intended.

Introducing a second compressible layer can change the way loads travel through that system.

Potential consequences of an unsuitable combination include:

• Increased local deflection: The boards may move further under concentrated loads if the supporting layers compress excessively.
• Locking-system stress: Repeated movement near plank connections may place additional pressure on the click-lock profiles.
• Joint separation: Excessive movement can contribute to visible gaps or damaged connections over time.
• Unwanted movement noise: An additional soft layer does not necessarily eliminate hollow or clicking sounds caused by inadequate support.
• Warranty disputes: A failure involving an unapproved installation assembly may complicate responsibility between the flooring supplier and installer.

These are potential failure mechanisms rather than inevitable outcomes. The actual risk depends on the floor construction, underlay properties, applied loads, substrate condition and installation method.

A higher-density acoustic rubber product may behave differently from lightweight foam. Thickness alone does not establish whether an underlay is suitable.

Similarly, a product marketed as suitable for hybrid flooring is not automatically compatible with every hybrid flooring brand.

Compatibility needs to be demonstrated for the complete assembly, including the particular locking system and supporting layers.

Acoustic Performance Cannot Be Judged by the Number of Layers

Additional material beneath a floor may seem likely to provide better sound insulation, but acoustic performance is not determined by thickness alone.

Impact sound transmission depends on several factors, including the finished flooring, supporting underlay, substrate, installation details and surrounding building construction.

An acoustic underlay that performs well beneath one flooring system may produce different results beneath another.

For a Sydney renovation requiring documented acoustic performance, a useful technical submission should identify:

• The exact flooring product and construction.
• The manufacturer and specification of the acoustic underlay.
• Whether the flooring includes factory-attached backing.
• The tested floor assembly and supporting test report.
• The test method and reported acoustic measurements.
• The substrate or structural floor configuration used in testing.
• Any installation conditions affecting the relevance of the results.

A laboratory result for one combination should not automatically be presented as evidence that a substituted combination will achieve the same performance.

Nor does an acoustic test result override a flooring manufacturer's prohibition on additional underlay.

Where building-specific performance is required, the relevant acoustic consultant should assess whether the proposed evidence is appropriate for the installation.

Extra Underlay Is Not a Substitute for Concrete Grinding or Floor Levelling

One of the more consequential mistakes in hybrid flooring installation is treating an acoustic layer as a means of correcting an uneven substrate.

These materials perform different functions.

Acoustic underlay is intended to contribute to the specified flooring assembly's sound-control performance. Floor preparation establishes the physical conditions needed for the floor to operate correctly.

In older Sydney houses and apartments, removal of carpet, vinyl, tiles or timber can expose conditions that were not visible during the original quotation.

Common examples include:

• Concrete ridges beneath previous floor coverings.
• Low areas that become apparent after removal.
• Adhesive residue from carpet or vinyl installations.
• Uneven patches from earlier renovations.
• Raised joints between adjoining substrate sections.
• Loose timber panels or damaged particleboard.

Placing additional cushioning over these defects does not make the underlying surface compliant with the flooring specification.

In some cases, it may allow additional movement where the boards already lack adequate support.

Manufacturer Flatness Limits Are Not Interchangeable

The Quick-Step Hybrid Vinyl Ciro installation instructions require correction of unevenness exceeding 1 mm over 200 mm or 4 mm over 2 metres.

Godfrey Hirst's Australian hybrid flooring installation instructions specify a solid, dry, clean substrate with a flatness requirement of 2 mm over 1000 mm.

These are product-specific requirements. They should not be applied indiscriminately to other hybrid flooring ranges.

For contractors preparing an existing slab, the appropriate sequence is to:

1. Remove the existing floor covering where required.
2. Inspect the exposed substrate for damage, contamination and moisture concerns.
3. Measure surface flatness against the selected flooring specification.
4. Complete appropriate grinding, repairs or levelling.
5. Verify that the prepared substrate satisfies the installation requirements.
6. Install the approved flooring and underlay arrangement.

Elyment's floor flatness tolerance guide for hybrid, vinyl and timber flooring explains why the selected product must determine the required preparation standard.

Surface correction should be completed using suitable methods and products. An additional acoustic layer is not an alternative to that work.

The Procurement Mistake That Can Delay a Sydney Flooring Installation

Consider an illustrative renovation in Sydney's Inner West involving the replacement of existing carpet with hybrid flooring.

The owner selects a hybrid plank with an attached acoustic backing. Separately, a supplier recommends an additional 3 mm acoustic underlay as a premium upgrade.

The flooring and acoustic materials are purchased before the installer receives the complete product specification.

When the installation contractor reviews the documents, the additional underlay is found to be unsupported by the selected flooring manufacturer's instructions.

The project now has a procurement problem rather than simply an installation question.

Possible consequences include:

• Returning or replacing the additional acoustic material.
• Obtaining technical clarification from the flooring manufacturer.
• Selecting a different flooring product if additional acoustic treatment is essential.
• Reviewing the proposed floor height and transition details.
• Revising acoustic documentation if the proposed assembly changes.
• Rescheduling installation while the specification is resolved.

The example is hypothetical, but the operational risk is straightforward: materials purchased independently may not form a compatible installation system.

Once the flooring has been delivered, changes become more expensive and harder to coordinate.

What Should Be Confirmed Before the Flooring Order Is Released?

For renovation managers, flooring installers and homeowners, a simple specification review can prevent incompatible materials from reaching the site.

1. Identify the Exact Flooring Product

Record the manufacturer, range, SKU, plank construction, attached backing and locking-system type.

A generic description such as "premium 7 mm hybrid flooring" is not sufficient to confirm compatibility.

2. Confirm Whether Additional Underlay Is Permitted

Check the manufacturer's current Australian installation instructions.

If a second acoustic layer is proposed, obtain written confirmation that the exact flooring and underlay combination is acceptable.

Do not rely solely on a retailer's description of the underlay as suitable for hybrid flooring.

3. Confirm the Complete Floor Build-Up

Document the proposed substrate, moisture-control layers, acoustic underlay, integrated backing, plank thickness and installation method.

Any membrane requirement must be checked separately. A moisture-control plastic sheet is not equivalent to an additional cushioning underlay.

4. Inspect the Existing Subfloor

Confirm whether grinding, repairs, adhesive removal or self-levelling compound will be needed.

Subfloor correction should be included in the project scope rather than left to the flooring installer to improvise.

5. Check Finished Floor Heights

Even a permitted additional 2 mm layer changes the finished floor build-up.

That difference may affect transition trims, door clearances, adjoining floor finishes and other interfaces.

These details should be checked before installation starts.

6. Record the Approved Specification

The final order and installation instructions should identify the agreed materials.

Any substitution should trigger a compatibility review before the replacement product is accepted.

This is particularly important where the flooring supplier, builder, acoustic consultant and installation contractor are different businesses.

NSW Apartment Renovations Require Two Separate Technical Decisions

For Sydney strata properties, flooring manufacturer compatibility and building acoustic requirements are separate matters.

The NSW Government's strata renovation guidance identifies installing or replacing hard flooring as work that generally requires approval through the applicable minor-renovation process. It also identifies acoustic certification as information to provide for flooring applications.

However, obtaining approval for an acoustic system does not automatically establish that the flooring manufacturer permits the proposed underlay combination.

Equally, a manufacturer-approved installation may still need separate evidence to satisfy the building's acoustic requirements.

Both conditions must be addressed where applicable.

Elyment has examined the broader approval process in its separate article on hybrid flooring acoustic underlay and strata approval in Sydney apartments.

The immediate procurement issue is narrower: confirm that the specific products being purchased are permitted to work together.

The Installation Handover Should Match the Approved Specification

Product compatibility is not fully resolved when a supplier confirms that two materials can be used together.

The installation must also follow the conditions attached to that approval.

For example, Godfrey Hirst's documented Damtec system includes requirements relating to substrate condition, underlay orientation, acclimatisation and the specified plastic layer.

Leaving out one of those components means the installed arrangement may no longer match the documented assembly.

A practical installation handover should therefore record:

• The flooring manufacturer, range and product code.
• The actual acoustic underlay installed, if applicable.
• The manufacturer instructions applying to the assembly.
• Any written compatibility clarification.
• Subfloor preparation and relevant inspection records.
• Moisture-management measures where required.
• Photographs of concealed layers before the floor is completed.
• Any approved product substitutions.

These records help distinguish a flooring product issue from a specification or installation issue if concerns arise later.

For projects involving separate trades, a clear handover record also makes responsibility easier to establish.

Elyment's analysis of self-levelling cement and acoustic underlay in Sydney apartment flooring quotations covers the related importance of identifying preparation and acoustic materials separately within the scope of works.

The Better Decision Is a Tested Floor System, Not More Material

Hybrid flooring manufacturers do not treat additional underlay as a universally interchangeable accessory.

Some products are designed to operate with their integrated backing alone. Others may be suitable for a specified additional acoustic system when all installation conditions are satisfied.

The difference can affect flooring performance, warranty exposure, material purchasing and project scheduling.

For Sydney renovation teams, the most reliable approach is to confirm the proposed assembly before buying additional underlay, assess the substrate independently and retain the relevant manufacturer documentation.

A properly prepared subfloor and a compatible flooring system provide a stronger basis for a successful installation than adding cushioning without technical approval.

Planning a Hybrid Flooring Installation in Sydney?

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Technical Sources and References

• Quick-Step Australia: Hybrid Vinyl Ciro Installation Instructions, May 2025.
• Godfrey Hirst: Hybrid Flooring Installation Over Damtec Acoustic Underlay, August 2025.
• Godfrey Hirst: Hybrid Floors Australian Installation Instructions.
• NSW Government: Strata Renovation Rules.

Editorial note: Manufacturer instructions and product specifications should be checked against the exact flooring range and current document revision before installation. Product-specific guidance takes precedence over general descriptions of hybrid flooring compatibility.