Hybrid flooring underlay

Most hybrid flooring comes with an underlay already attached. It is a thin soft layer fixed under each plank. In November 2026 we read the official supplier pages of 111 hybrid ranges. A range is one product line from one supplier. On 88 ranges the supplier stated an attached underlay. So with a hybrid floor the main question is not which underlay to choose. It is whether a second one may go under your floor at all.

What the attached underlay is

The attached underlay is a thin layer of foam or cork. It is fixed under the plank in the factory. It softens the sound of footsteps in the room and the feel under your feet.

• How thick. On 17 of the 111 ranges the supplier named its thickness. It was 1 mm on 4 ranges, 1.5 mm on 12 ranges and 2 mm on 1 range.
• What it is made of. We also read the suppliers' own web pages for 85 ranges. For 16 ranges the page named IXPE, a kind of foam. For 2 ranges it named cork. For 1 range it named EVA, another kind of foam.
• Not stated. On 23 of the 111 ranges, the pages we read did not say if an underlay is attached. Ask the supplier before you order.

Does hybrid flooring need underlay?

Usually not a separate one. A plank with an attached underlay already has its soft layer. We read the installation instructions of 14 suppliers. For 2 of them these were the instructions of one herringbone range. 9 of the 14 speak about a second underlay. None of them asks for one in a normal house.

• 4 state that a second soft or foam underlay is not to be used under their planks. Two of them give the reason: it can weaken the click joints of the planks.
• 5 state that a second underlay is not needed or not recommended, or that it needs a supplier's approval or instructions.

The other 5 do not speak about a second underlay.

If your floor has no underlay attached, ask the supplier which underlay it needs.

Underlay and plastic film are two different things

A plastic film is a moisture barrier. It keeps damp from the subfloor away from the planks. The subfloor is the floor under your new floor. A film is not an underlay, and it does not soften sound. One supplier states in plain words that its attached underlay holds no moisture barrier.

9 of the 14 suppliers speak of a plastic film or another damp-proof layer under the planks. Each supplier is counted once in this list.

• 3 state it under every floor.
• 1 states it on every concrete subfloor.
• 4 state it on concrete where the moisture was not tested, or where the reading is too high.
• 1 states it only over a heated slab.

Where a thickness is stated, it is 200 microns, or 150 microns or more. A micron is one thousandth of a millimetre.

Acoustic underlay for hybrid flooring in apartments

In an apartment, footsteps on a hard floor can be heard in the home below. An apartment building can have its own noise rules for hard floors. Ask your owners corporation or building manager what your building requires, before you order.

Some buildings need more sound control than the floor gives. 4 of the 14 suppliers speak of a second layer of cork or rubber under the planks for sound. None of them names a soft foam for it. A supplier can be in more than one line of this list.

• 3 of the 4 state it for the case where more sound control is needed.
• 1 asks for its own approval first.
• 2 state that you should check with an acoustic specialist or an acoustic engineer.
• 1 states a plastic film between this layer and the planks, so the underlay of the planks does not grip it.

What a 5 star or 6 star acoustic rating means

The star rating comes from the Association of Australasian Acoustical Consultants (AAAC). It is part of its guideline for apartments and townhouses. For footsteps through a floor, the guideline uses a measured number, written LnT,w. A lower number is better. The association's words are: "The lower the Lnt,W the better the impact sound insulation." The association writes the name of this number in both ways.

These are the limits in the guideline for floors between two homes.

• 6 stars: 40 or lower.
• 5 stars: 45 or lower.
• 4 stars: 50 or lower.
• 3 stars: 55 or lower.
• 2 stars: 65 or lower.

Suppliers often print a star rating on the web page of a range. We read 75 of these pages. 24 of them stated an acoustic star rating. It was 5 stars on 12 pages and 6 stars on 11 pages. One page showed 6 stars in one place and 5 stars in another.

A star rating belongs to a whole floor, not to a plank or an underlay alone. The guideline states: "The star rating system measures the actual installed performance of the wall or floor system." In 2023 the association added a note. It states: "It cannot and should not be claimed that any particular building product (eg underlay) in isolation will achieve a certain acoustic rating, particularly where the floor/ceiling system details are different to that initially tested."

So a star rating on a range page tells you about the floor that was tested. That means the plank, the concrete slab or timber floor under it, and the ceiling below. Your building can give a different result.

What to ask about an acoustic rating

1. Ask the supplier for the test report of the range.
2. Read which floor was tested. The association's note states that the rating claim "should be evidenced by laboratory or field test results and the complete floor/ceiling system build-up clearly listed". Of the 75 pages we read, 7 gave a measured number. Three of them also named the tested floor: a 150 mm concrete slab with a ceiling under it.
3. Compare the tested floor with your building. A thinner slab, or no ceiling below, can change the result.
4. Get your building's rule in writing, with the number or the stars it asks for.
5. If you need to be sure, the association's note states: "For certainty, the finished floor should be tested".

Sources of the quotes: Guideline for Apartment and Townhouse Acoustic Rating, Version 1.0 (June 2017); Explanatory notes regarding the impact sound insulation rating, Version 2.0 (May 2023).