Soundproof Flooring for Apartments: What Reduces Noise

No hard floor is truly soundproof. What your neighbours below will hear is impact noise, footsteps and dropped things travelling through the slab, and the thing that reduces it most is the acoustic underlay or mat under the boards. Most owners corporations set a minimum acoustic performance for hard floors, so choose the board and underlay together, check them against your building’s rules, and get approval before anything comes up.

The two kinds of noise

When people say they want a quiet floor, they usually mean one of two different things.

Impact noise is what happens when something strikes the floor: heels, a dropped spoon, a chair dragged back from the table, kids jumping off the couch. The energy goes into the slab and comes out as sound in the apartment below. Carpet absorbs a lot of it. A hard floor laid straight onto concrete absorbs very little. This is the noise building rules are written about.

Airborne noise is voices, music and the television. It travels mostly through walls and the slab itself, and changing the floor covering has little effect on it. If a neighbour can hear your TV, a new underlay won’t solve it.

There is also the noise you hear in your own apartment. A hard floor makes a room more echoey, and some floors give a sharper click underfoot than others. Rugs, curtains and soft furniture help here far more than the floor does.

Start with your building’s rules

Before you look at a single sample, get a copy of your owners corporation rules from your manager or committee, and read the section on floor coverings. Buildings differ a lot. The main points to look for are:

• whether you need written approval before replacing carpet with a hard floor
• whether the rule names an acoustic rating, and whether it is a laboratory rating for the product or a test done in your apartment after installation
• whether an acoustic consultant has to sign off
• permitted hours for noisy work such as grinding and removal
• lift bookings, loading bay access and protection for common areas

If the rules are vague, ask the manager in writing what they will accept, and keep the reply. It is much easier to meet a clear requirement at the start than to resolve a disagreement about a floor that is already down.

The underlay does most of the work

An acoustic rating applies to a combination: a particular board, on a particular underlay, over a slab of a particular thickness, tested in a particular way. A board on its own doesn’t really have an acoustic rating, and neither does an underlay listed on its own in a brochure. When a supplier quotes a figure, ask for the test report and check that it matches your setup.

Thicker and softer is not automatically better. Floating floors need firm support at the joints. An underlay that is too soft lets the boards flex, which leads to creaking, joints opening and, with click floors, broken locking profiles. That is why manufacturers list the underlays they approve for each product. We choose the board and underlay as a pair for exactly this reason.

Questions to ask about any acoustic claim

Acoustic figures are often quoted loosely in apartment flooring. Before you rely on one, we suggest asking:

• Is the figure for the board and underlay together, or for the underlay alone?
• Was it measured in a laboratory, or in a real apartment after installation? Your building may want one or the other.
• How thick was the slab in the test, and was there a ceiling below? A thinner slab than yours, or a ceiling that yours doesn’t have, changes the result.
• Can I have the full test report as well as the brochure?

If the answers don’t match your apartment, the number doesn’t tell you much. That is why we match the combination to your building’s rules rather than quoting a figure from a sales sheet.

Floating or glued in an apartment

Floating the floor over an acoustic underlay is the most common approach in apartments. It keeps the boards separated from the slab, which is what you want for impact noise, and it avoids the adhesive work that some buildings restrict.

Glued floors can also be used with an acoustic mat system bonded between the slab and the boards. They feel more solid and give a less hollow sound in your own apartment, but the system has to be tested as a whole to show what it achieves. Our post on floating floor vs glue down covers the wider trade-offs.

Which floor for an apartment

Floor	How it’s laid	In an apartment
Engineered oak, 15 mm, 4 mm oak wear layer	Glued with an acoustic system, or floated where the product allows	Real timber surface. Needs a flat slab and the right underlay or mat.
Laminate, 12 mm, 5G click	Floating on underlay	Hard-wearing and quick to lay. Can sound sharper underfoot in your own apartment, which the underlay softens.
Hybrid	Floating, often with an attached underlay	Water-resistant core. Check whether the attached underlay meets your building’s rule on its own.
Carpet	Stretched over underlay	Best at impact noise, which is why buildings treat replacing it carefully.

You can see the specs for our engineered oak and laminate online. For hybrid, we have samples in the showroom. We suggest looking at them side by side and listening to each one in hard-soled shoes.

Where noise leaks around the edges

The details can undermine a good underlay. Sound takes the easiest path, and if the floor touches the building anywhere, some of it goes that way instead.

1. Perimeter gaps. The boards should stop short of the walls, with the gap covered by skirting or scotia, not packed with anything hard.
2. Skirting and scotia fixing. These should be fixed to the wall, not down through the floor into the slab.
3. Kitchen cabinets and pipes. Where the floor meets cabinet kickers, door frames and pipe penetrations, a flexible sealant keeps the floor isolated.
4. Fixings through the underlay. Screwing or nailing anything through the floor into the concrete bridges the acoustic layer at that point.
5. Furniture. Felt pads under chairs and stools cut scraping noise more than most people expect. They are one of the least expensive acoustic improvements you can make.

What you find under apartment carpet

Once apartment carpet comes up, the slab is often rougher and less level than it looked. There may be old adhesive, gripper holes and dips near balcony doors. A floating floor over a dip flexes and clicks, which is unpleasant for you and noisy for the people below, so levelling is part of doing an apartment floor properly. It is covered on our floor removal and subfloor page. If you’re in one of the towers around Box Hill Central, our Box Hill page also covers new apartments handed over with a builder’s floor already down.

Planning the job in a building

Apartment installs have more moving parts than houses. Removing carpet and grinding a slab is noisy, so it needs to fit inside the permitted hours. Boards, underlay and rubbish all go up and down in the lift, which usually means a booking and lift protection. Some buildings ask contractors to sign in or show paperwork before starting.

It is courteous to let your neighbours below know before work starts. A short note with the dates is usually appreciated, and they will be living under your floor for years. Once it’s down, a few habits help: house shoes instead of heels, pads under stools, and not dragging furniture. Those habits do as much for the people below as the underlay does.

Next step: bring the rules with you

Bring a copy of your owners corporation rules, and the approval form if there is one, to the showroom or to a free measure and quote. We’ll check the board and underlay combination against what the building asks for before you commit, and the quote will list the underlay, levelling and removal as separate lines. You’re welcome to visit us at 2/1386 Toorak Road, Camberwell, or call 1300 690 160 to book.