If you own an apartment and you're dreaming of replacing carpet with timber floors, there's one word your strata committee will want to hear before anything else: acoustics. Impact noise — footsteps, dropped keys, dragged chairs — is the single biggest reason hard floor applications get knocked back by owners corporations. Get the acoustic underlay right, and the approval process is straightforward. Get it wrong, and you could be looking at a rip-out order months after installation.

At Acorn Timber Flooring, REGUPOL acoustic underlay is our go-to system for apartment and multi-residential installations across Sydney. Here's what it involves, what the Building Code actually requires, and — critically — what paperwork you'll need before your strata committee will sign off.

Why acoustic underlay matters more in apartments than anywhere else

In a freestanding house, underlay is about comfort and floor feel. In an apartment, it's about your neighbours downstairs. Timber floors transmit impact sound far more readily than carpet, and that sound travels straight through a concrete slab into the unit below. An acoustic underlay sits between your timber flooring and the slab, absorbing and dampening that impact energy before it becomes someone else's problem.

This isn't optional in strata buildings. Most owners corporations have a by-law specifically covering hard floor coverings, and almost all of them require documented proof that your flooring system meets a minimum acoustic performance standard before work begins.

What the National Construction Code actually requires

The National Construction Code (NCC), under Part F7 — Sound Transmission and Insulation, sets the minimum standard for floors separating apartments in Class 2 buildings. The figure you'll see referenced constantly is:

• Weighted standardised impact sound pressure level (LnT,w), or the older Ln,w + Ctr notation: not more than 62 dB

In plain terms: the lower the number, the quieter the floor. A rating of 62 dB is the legal minimum for new construction — it is not necessarily what your strata by-laws will accept, and it's often not enough to genuinely satisfy the neighbours below you.

A few things worth knowing:

• By-laws frequently set a stricter benchmark than the NCC. Many Sydney strata schemes require Ln,w of 55 or even 50, particularly in premium or older buildings where slabs are thinner.
• Lab results don't automatically transfer to your building. REGUPOL's published performance figures are generated under controlled lab conditions on a specific slab thickness and construction type. Your building's actual slab, ceiling treatment, and construction will affect real-world performance — which is exactly why on-site or system-specific test evidence matters, not just a product brochure.
• Slab thickness is a major variable. Older buildings with 150mm slabs behave very differently to newer builds with 200mm+ slabs. The same underlay can pass in one building and fail in another.

The REGUPOL range we specify

REGUPOL is one of the most widely tested and specified acoustic underlay brands in the Australian market, with a NATSPEC-recognised worksection and a product range built specifically around different timber flooring build-ups. Depending on your flooring system and the acoustic target for your building, we typically work with:

• REGUPOL sonus core — a rubber crumb underlay designed for floating floor installations under engineered timber, T&G, parquetry and bamboo, commonly used across multi-residential projects.
• REGUPOL sonus curve — a 3D dimple-profile underlay (available in multiple thicknesses) purpose-built for apartment-grade sound isolation under solid and engineered timber.
• REGUPOL sonus multi — a lightweight, direct-stick system suited to engineered timber, laminate and bamboo where a glue-down build-up is preferred.
• REGUPOL sonus eco — a sustainability-focused option manufactured from recycled tyre and cork elastomer, GECA-certified for green building projects.

The right product depends on your slab construction, your flooring build-up (floating vs direct stick), your building's specific acoustic target, and whether the installation needs to satisfy a sustainability rating alongside its acoustic performance. This is a specification decision, not a one-size-fits-all pick — which is exactly why we work through it with each client rather than defaulting to a single product.

What test and data sheets you'll actually need

This is where most DIY approvals stall. Owners corporations don't accept "the underlay is rated for apartments" as evidence — they need documentation. Before submitting a hard-floor application, you should have:

1. An independent acoustic test report. This should show results from an accredited laboratory (or, ideally, on-site testing for your specific building) using the relevant Australian testing standard for impact sound (AS ISO 717.2 based testing methodology). It needs to state the LnT,w / Ln,w + Ctr figure for the tested floor build-up — not just the underlay in isolation, but the full system: your specific timber flooring product, adhesive or fixing method, and the REGUPOL underlay together.
2. REGUPOL technical data sheets for the specific underlay product being installed, confirming thickness, composition, compressive strength and the manufacturer's published acoustic performance figures.
3. Written confirmation from your flooring supplier that the proposed system — timber + underlay + installation method — meets both the NCC F7 requirement and your building's specific by-law figure, where one exists.
4. A copy of your building's specific by-law on hard flooring, checked against the test evidence before you submit — some schemes prohibit certain underlay types outright or require testing by a specific acoustic consultancy.

For higher-risk buildings — older slabs, previous noise complaints, or particularly strict by-laws — we recommend engaging an independent acoustic consultant to review the proposed system and, where necessary, arrange in-situ testing after installation. It's a more rigorous step, but it protects you from a rip-out order down the track, which costs far more than the testing itself.

How Acorn manages this for you

When we quote an apartment installation, acoustic compliance is built into the process from day one — not an afterthought once the floor is down. We'll:

• Recommend the appropriate REGUPOL underlay for your slab and flooring build-up
• Provide the technical data sheets and test reports needed for your strata application
• Confirm compliance against both the NCC minimum and any stricter by-law figure your building specifies
• Advise when independent acoustic consultation is warranted before work begins and provide a recommendation of an Acoustic engineer.

Getting this right the first time means your strata application moves through committee without delay — and your downstairs neighbours never know you've renovated at all.

Planning a timber floor installation in a Sydney apartment? Get in touch with the Acorn Timber Flooring team at our Surry Hills showroom on (02) 9167 3624, and we'll help you put together an acoustic package your owners corporation will approve.

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