Does Laminate Flooring Need Underlay in Australia?

A new laminate floor can look fantastic on day one, but what sits beneath it often determines how it feels, sounds and performs over the years. So, does laminate flooring need underlay? In most floating-floor installations, yes - but the right answer depends on the laminate product, the subfloor and whether the boards already have an attached underlay.

Underlay is not simply an optional layer of foam. It can provide cushioning, reduce sound, help manage moisture and support a more even installation. Just as importantly, the wrong underlay - or using a second layer where one is already attached - can create movement in the floor and affect the manufacturer’s warranty.

Does laminate flooring need underlay on every job?

Most laminate flooring is installed as a floating floor, meaning the boards click together and sit over the subfloor rather than being fixed directly to it. An appropriate underlay beneath the boards gives that system the support it needs.

There are two common exceptions. Some modern laminate products are manufactured with an acoustic or comfort backing already attached to every board. In this case, a separate foam underlay is usually not required and may be specifically prohibited. The other exception is where the manufacturer specifies a particular installation system for a particular substrate. Their instructions should always take priority over general rules.

This is why selecting underlay should happen alongside selecting the laminate, not as an afterthought. A quality laminate plank with the incorrect backing underneath can feel less stable than it should, particularly in busy family areas where there is regular foot traffic, pets, chairs and kids at play.

What underlay actually does beneath laminate flooring

The best underlay is chosen for the conditions of the home, rather than simply choosing the thickest option on the shelf. Its role can include several practical benefits.

It improves comfort and sound

Laminate is a hard, durable surface. A suitable acoustic underlay can soften the feel underfoot and reduce the hollow tapping sound sometimes associated with floating floors. This makes a noticeable difference in living areas, hallways and upstairs rooms, where footsteps can otherwise travel through the home.

For apartments, townhouses and commercial spaces, acoustic performance may also be a body corporate or tenancy requirement. In these settings, the underlay’s tested acoustic rating matters more than a broad claim that it is “sound reducing”.

It helps protect against moisture from below

Concrete slabs can hold and release moisture, even when they appear completely dry. For laminate flooring over concrete, moisture protection is often essential. Depending on the product and site conditions, this may mean an underlay with an integrated vapour barrier or a separate moisture membrane beneath the underlay.

This is particularly relevant for ground-floor homes, newer concrete slabs and renovation projects where the existing floor covering has been removed. Moisture testing and proper subfloor preparation are the reliable way to assess the risk. Guesswork can lead to swelling, damaged joints or a floor that fails well before it should.

It smooths minor imperfections, not major defects

A good underlay can take up very slight texture or tiny irregularities in a prepared subfloor. It does not level a floor. If there are hollows, ridges, cracked areas or noticeable changes in height, they need to be repaired or levelled before laminate is installed.

Trying to hide an uneven slab with a thicker underlay is a common and costly mistake. The floor may flex when walked on, click joints can become stressed, and boards may eventually separate or chip at the edges. Proper floor levelling creates the stable base that laminate needs to perform properly.

Concrete, timber and existing floors: the subfloor changes the answer

The subfloor is one of the main factors behind the question of whether laminate flooring needs underlay.

Over a concrete slab, laminate generally needs a moisture-management layer that meets the product’s specifications. This may be built into the underlay, but it should never be assumed. The slab must also be clean, dry, flat and properly tested before work begins.

Over a timber subfloor, underlay is commonly used for acoustic comfort and to help the floating floor sit consistently. Any loose boards, squeaks, high points or damaged sections should be addressed first. The timber subfloor must be structurally sound and within the laminate manufacturer’s flatness tolerance.

When installing over an existing hard floor, such as ceramic tiles, the same principles apply. The existing surface needs to be secure, flat and free of significant lipping between tiles. Underlay can support the laminate system, but it cannot correct loose tiles or an uneven base.

Carpet, old underlay and soft resilient flooring are generally not suitable bases for laminate. These surfaces allow too much movement and can compromise the click-lock joints. They should be removed so the condition of the subfloor can be assessed properly.

Attached underlay: when more is not better

Many premium laminate ranges now include an attached backing. This can simplify installation and deliver the comfort and sound performance the product was designed to provide.

If your laminate has attached underlay, do not automatically add another layer underneath. Doubling up can make the floor too soft, allowing excess vertical movement at the joins. That movement can cause gaps, creaking, broken locking mechanisms or warranty issues.

There is one important nuance: attached backing does not always replace the need for a moisture barrier over concrete. Some products with pre-attached acoustic pads still require a separate approved vapour barrier. Check the installation instructions for the exact laminate range and the type of subfloor beneath it.

Choosing the right underlay for an Australian home

There is no single “best” underlay for every property. The right choice balances moisture protection, acoustic needs, floor height, subfloor condition and the laminate manufacturer’s requirements.

A busy household may benefit from a quality acoustic underlay that makes the floor quieter and more comfortable in everyday use. A home built on a concrete slab may need a product with verified vapour protection. In a renovation, finished floor height can be critical where laminate meets existing tiles, cabinetry, sliding doors or stair finishes.

Thickness should not be treated as a shortcut to quality. Very thick, soft underlays are not always appropriate for click-lock laminate because they can allow too much movement. A denser underlay at the approved thickness often gives better support and a more solid feel underfoot.

For South Australian homes, conditions can vary significantly between older properties, new builds and coastal locations. A professional site inspection helps identify issues that are easy to miss before installation, including slab moisture, floor flatness and height transitions between rooms.

Preparation matters as much as the underlay

Underlay performs best when the preparation beneath it is right. Before laying laminate, the subfloor should be checked for moisture, flatness, cleanliness and structural stability. Dust, building debris and small pieces of old adhesive can create pressure points beneath a floating floor.

Expansion gaps also matter. Laminate naturally expands and contracts with changes in temperature and humidity. Installers leave the specified clearance around walls, door frames, cabinetry and fixed objects so the floor has room to move without buckling. Underlay does not remove this requirement.

At Thinking Flooring, this preparation is treated as part of the installation, not an optional extra. Whether the job needs concrete grinding, floor levelling or a moisture-management solution, getting the base right protects the finished result.

Signs your laminate floor may have the wrong support underneath

Problems are not always caused by underlay alone, but certain signs are worth investigating. A floor that feels bouncy, makes excessive clicking noises, develops open joints or shows lifted edges may be reacting to an uneven subfloor, unsuitable underlay or missing expansion space.

Moisture-related issues can include swelling around board edges, raised joins or changes near external walls and wet areas. Laminate is durable, but it is not a substitute for addressing water leaks, slab moisture or unsuitable room conditions.

If you are replacing an existing floor, removing it before making assumptions is often the sensible approach. It reveals the actual state of the subfloor and allows any required repairs to be completed before the new laminate goes down.

A well-chosen underlay will not be the part of the floor you see, but you will notice the difference every time you walk across it: a quieter, firmer and more comfortable surface that is properly supported from the ground up.