Which underlay do I need for my floor?
6 min read · Written by the WFA flooring team · Updated June 2026
Quick answer
Laminate always needs a separate underlay. Hybrid planks usually come with underlay pre-attached, so you rarely need extra. Engineered timber glued down needs no underlay; floating engineered timber does. If you're in an apartment, check your strata bylaws — you'll likely need an acoustic underlay rated at least 50 dB impact sound reduction. Over concrete, always add a moisture barrier if your underlay doesn't include one.
Laminate (floating)
Separate underlay needed?: Yes — always
Moisture barrier needed?: Yes, over concrete
Acoustic option available?: Yes — choose acoustic foam or felt
Hybrid with attached underlay
Separate underlay needed?: Usually no
Moisture barrier needed?: Built-in film usually sufficient
Acoustic option available?: Upgrade to acoustic underlay if strata requires it
Hybrid without attached underlay
Separate underlay needed?: Yes
Moisture barrier needed?: Yes, over concrete
Acoustic option available?: Yes
Engineered timber (floating)
Separate underlay needed?: Yes
Moisture barrier needed?: Yes, over concrete
Acoustic option available?: Yes
Engineered timber (glued down)
Separate underlay needed?: No
Moisture barrier needed?: Use adhesive with moisture-control properties
Acoustic option available?: Limited — check adhesive spec
Porcelain tiles
Separate underlay needed?: No — bedded in adhesive
Moisture barrier needed?: Membrane applied separately
Acoustic option available?: Not applicable
| Floor type | Separate underlay needed? | Moisture barrier needed? | Acoustic option available? |
|---|---|---|---|
| Laminate (floating) | Yes — always | Yes, over concrete | Yes — choose acoustic foam or felt |
| Hybrid with attached underlay | Usually no | Built-in film usually sufficient | Upgrade to acoustic underlay if strata requires it |
| Hybrid without attached underlay | Yes | Yes, over concrete | Yes |
| Engineered timber (floating) | Yes | Yes, over concrete | Yes |
| Engineered timber (glued down) | No | Use adhesive with moisture-control properties | Limited — check adhesive spec |
| Porcelain tiles | No — bedded in adhesive | Membrane applied separately | Not applicable |
Why underlay matters
Underlay sits between your subfloor and your new flooring. It does three jobs: it cushions foot traffic to make the floor feel softer underfoot, it absorbs minor subfloor imperfections (most underlays tolerate up to 3 mm variation per 1.8 m), and it slows moisture migration from concrete slabs — a real concern in Australian homes built on ground-bearing slabs.
Skip the right underlay and you risk a floor that sounds hollow, develops squeaks, traps moisture under the planks, or — if you're in a strata building — breaches body corporate rules and has to be ripped up. Choosing correctly the first time saves money and hassle.
Laminate flooring — always use a separate underlay
Laminate is a rigid board with a timber-effect printed layer fused over an HDF core. Because it has no cushioning built in, it always needs a separate underlay. A standard foam underlay (around 2–3 mm) works fine on timber subfloors. Over a concrete slab, choose an underlay that combines foam cushioning with a built-in polyethylene moisture barrier — look for the silver foil or film laminated to the underside.
If your apartment strata plan requires impact sound insulation (commonly 50–54 dB LnTw or better), choose a thicker acoustic foam or recycled-felt underlay rated to meet that figure. Check the product data sheet before you buy, and keep a copy for your building manager. WFA stocks underlay accessories online — use the box calculator on each product page to work out exactly how many rolls you need with waste accounted for.
Hybrid flooring — check for attached underlay first
Most hybrid planks sold in Australia — including the Clever Choice and Preference Floors ranges at WFA — come with a thin foam or cork layer pre-attached to the back of each plank. If yours does, you do not need (and should not add) a second full underlay layer, as stacking two foam layers causes the locking joints to flex and can lead to joint failure over time.
There is one exception: if your strata bylaw requires a higher acoustic rating than the pre-attached layer delivers on its own, you may be able to add a thin acoustic mat beneath — but check the flooring manufacturer's installation guide first, as some brands limit the total combined thickness. Where hybrid planks have no attached underlay (less common), treat them the same way as laminate and choose a foam-plus-moisture-barrier underlay for concrete, or plain foam for timber subfloors.
Engineered timber — floating vs glued
Engineered oak timber from WFA starts from $60.50/m2 and is commonly installed one of two ways. If you're floating the boards over a subfloor, you need an underlay — foam with integrated moisture barrier over concrete, or plain foam over particleboard or plywood. If you're gluing the boards directly to a concrete slab with a flexible timber adhesive, no underlay goes down: the adhesive itself bonds to the slab and the plank. Some specialist adhesives also include moisture-control properties; check the product datasheet or ask us at info@wholesalefloorsaustralia.com.au before ordering.
Engineered timber is more dimensionally stable than solid hardwood but it still expands and contracts with humidity changes. Good underlay for floating installations helps even out minor subfloor undulation and reduces the hollow 'tap' sound you sometimes hear with timber floors — a common concern in open-plan homes.
Ordering underlay from WFA
WFA sells underlay and accessories online at wholesale prices, with live freight pricing calculated at checkout. Delivery to Sydney Metro and Newcastle generally takes 1–3 business days; Hunter Valley, Central Coast, Southern Highlands and Illawarra 2–4 business days; interstate 4–7 business days. The minimum delivered freight charge is $97.14 including fuel levy and GST, so it often makes sense to order your flooring and underlay together in one shipment to keep freight costs down.
If you'd prefer to inspect products before buying, you're welcome to collect from our depot at 24–27 Crescent Street, Holroyd NSW 2142 (near Merrylands and Parramatta), Monday to Friday 8 am–4 pm. Orders are usually ready for collection in about 24 hours. Create a free account online and you'll receive 5% off your first order — a handy saving when you're buying underlay across multiple rooms.