LVT underlay: when you need it, and when you don't

Glue down LVT never takes an underlay. Click floors may, unless one is built in. What goes under each, and what one room costs.

The quick answer

Glue down LVT never goes on an underlay. It is stuck straight to a smooth, flat, dry subfloor, and an underlay would let it move and lift. Click LVT and click SPC float, so they do need something soft underneath, but most now come with it built in, and every click floor we sell does. If yours has one built in, do not add another. The only thing you may still need under a click floor is a damp proof membrane on concrete.

This is for anyone about to buy LVT who has been asked "and which underlay?" and is not sure they need one. It covers glue down and click, what each one goes on instead, the jobs where something extra is worth it, and what a room costs with and without. Prices were checked on 13 November 2026 and include VAT.

Glue down or click: the one question that decides it

There are two ways LVT goes down, and they want opposite things underneath.

Glue down LVT is thin (about 2 to 2.5 mm) and flexible. It is stuck to the subfloor with an adhesive across its whole back. It needs a hard, smooth base so every bit of it is bonded.
Click LVT and click SPC are thicker planks that lock together at the edges and float on the subfloor, held down by their own weight. They need a thin cushion to take out small bumps and soften the sound of footsteps.

If you are not sure which you are looking at, the product name on our site always says. Our glue down vs click guide covers how to choose between them.

At a glance

	Glue down LVT	Click with built-in underlay	Click with no underlay attached
Underlay?	Never	No: it is already there	Yes, a thin one made for LVT or SPC
What goes under it	Smoothing compound on concrete, plywood on boards	The subfloor, plus a damp proof membrane on concrete if the fitting guide asks	The underlay, plus a membrane on concrete if the underlay has none
Extra cost per m²	£0 for underlay (adhesive instead)	£0	Whatever the underlay costs
Our floors	Daytona, Textures, Kulta, Invictus glue down	Nordikka SPC, Invictus Maximus Click, Amtico Click Smart	None

Why glue down LVT never takes an underlay

Put a soft layer under a glue down plank and three things go wrong. The adhesive has nothing firm to grip, so the plank lifts. The plank flexes every time someone steps on it, so the edges open up. And a dent in the soft layer shows straight through 2 mm of vinyl.

What glue down needs instead is a better base:

On concrete or screed: dry (under 75% RH), then a smoothing compound so the surface is flat and free of dust. Small dips and trowel marks will show through otherwise.
On timber floorboards: plywood screwed down over the boards, so the joins between boards do not show through or move.
Then the adhesive: a pressure sensitive LVT adhesive such as UZIN KE 49 HT, spread with an A2 notched spreader.

The tests and the limits for each subfloor are in our subfloor preparation guide, and the whole job is in our guide to laying glue down LVT. Money you were going to spend on underlay is better spent here: the base is what makes a glue down floor look right for twenty years.

Click floors: check for a built-in underlay first

Most click floors now come with a thin underlay bonded to the back of every plank: foam, cork or a rubbery layer about 1 mm thick. Every click floor we sell has one. Nordikka Woodland Fir herringbone SPC, for example, is 6 mm with its underlay attached, and Invictus Maximus Click has a cork backing.

If the underlay is built in, do not add a second one. It sounds like more comfort, but it makes the floor soft, the planks flex at the joins, and the locking edges can crack or open. Most makers say this in their fitting guide, and some will not honour a guarantee if a second underlay is used.

What you may still need is a damp proof membrane on a concrete or screed floor: a sheet of polythene laid first, with the joins overlapped and taped. A concrete slab can give off moisture for years, and the membrane keeps it off the back of the planks. Check the fitting guide for your floor: some built-in underlays include a moisture barrier and some do not. On timber floors you do not want a polythene sheet, because the boards need to breathe.

If you buy a click floor elsewhere that has no underlay attached, use a thin, firm underlay made for LVT or SPC (the fitting guide will give the thickness), never a thick carpet or laminate underlay.

When something extra underneath is worth it

Flats. Many leases ask for a sound rating on any hard floor. Read yours before you buy. The built-in underlay on a click floor helps, but it may not meet the figure on its own. For glue down there are acoustic mats made to go under the adhesive. We do not sell these, so ask your fitter which one meets your lease.
Underfloor heating. Everything between the heating and your feet slows the heat down. Keep the total under 1.5 tog and the floor surface at no more than 27°C. Glue down LVT is the best choice here, with nothing in between. Adding a second underlay under a click floor wastes heat. Our underfloor heating guide has the detail.
Old, uneven floors. An underlay will not fix a floor that is out of level. It just hides the dip until the planks start to rock. Level the floor first.

Mistakes we see

Laying LVT over old carpet underlay. Always lift it.
Putting laminate underlay under glue down LVT. Glue down goes on a hard base, nothing else.
Adding a 3 mm foam underlay under a click floor that already has one. The joins give way within months.
Skipping the membrane on a new screed. Let the screed dry, test it, then lay the membrane if your floor needs one.

What a room costs, with no underlay to buy

Here is the working for a 15 m² living room on a concrete floor in Daytona Natural Oak plank, our own LVT range, checked on 13 November 2026:

Floor: 15 m² plus 10% for cuts is 16.5 m². 16.5 ÷ 3.685 = 4.48, so 5 packs (18.43 m²). 5 x £84.72 = £423.60.
Adhesive: at 3 to 3.5 m² per kg, 15 m² needs about 4.3 to 5 kg, so one 6 kg tub of UZIN KE 49 HT at £79.99.
Spreader: one A2 notched spreader at £9.95.
Underlay: none, £0.
Total: £513.54 inc VAT, plus the smoothing compound for your floor, which your fitter will price once they have seen it.

The same room in Nordikka Woodland Fir herringbone SPC: 16.5 ÷ 1.114 = 14.81, so 15 packs (16.71 m²). 15 x £30.02 = £450.30 inc VAT, with the underlay already on the back and no adhesive needed. Add a damp proof membrane from your merchant if the fitting guide asks for one.

Daytona has a 0.55 mm wear layer and a 25 year residential guarantee and a 10 year commercial guarantee, backed by Flooring Monster. For your own room, use the flooring calculator and the LVT adhesive calculator.

LVT underlay questions people ask

Do you need underlay for LVT?

Not for glue down LVT: it is stuck straight to a smooth subfloor. Click LVT and SPC need a thin underlay, but most have one built in, and if yours does you need nothing extra apart from a damp proof membrane on concrete where the fitting guide asks for it.

Can you put underlay under glue down LVT?

No. The adhesive needs a hard base to grip, and a soft layer lets the planks flex, lift and show dents. The exception is an acoustic mat made for glue down LVT, which goes under the adhesive in flats where the lease asks for a sound rating.

Can you put underlay under click LVT that already has underlay?

No. A second layer makes the floor too soft and the joins can open or break. Most makers say not to, and it can affect the guarantee.

Do I need a damp proof membrane under LVT?

For a click floor on concrete or screed, usually yes, unless the fitting guide says the built-in underlay already does that job. For glue down, the slab must be dry before you start (under 75% RH), and a damp slab needs a liquid damp proof treatment, not a sheet.

What thickness of underlay for click LVT?

Thin and firm, as the fitting guide says, usually around 1 to 1.5 mm. Never a thick carpet or laminate underlay. If the planks have one built in, you need none.

Does LVT feel hard without underlay?

It feels firmer than carpet and warmer and quieter than tile. Glue down feels solid underfoot, like a stone or wood floor. Click floors with a built-in underlay have a little more give.

Next steps

Order up to five free samples and feel the difference between a glue down and a click plank in your hand.
Browse the Daytona range or the click SPC floors.
Still choosing? Start with what LVT flooring is, our LVT buyer's guide, the laminate vs LVT comparison or the which floor for which room guide.

Written by Flooring Monster. Facts and prices checked 13 November 2026. Moisture figures are from BS 8203; product figures are from our live product pages. Questions? Call us free on 0800 870 8795.