How to use self-levelling compound under LVT

How to mix, pour and finish self-levelling compound so a glue down LVT floor goes down flat, with the bag maths and drying times worked through.

The quick answer

Clean and prime the floor, seal the edges, then mix one bag at a time with exactly the water the bag says and pour it in strips, keeping a wet edge. Most compounds use about 1.5 kg of powder per m² for each millimetre of depth, so a 20 kg bag covers roughly 4.4 m² at 3 mm. Leave it to dry for the time on the bag (often about 24 hours at 3 mm) before you glue LVT down. Glue down LVT needs the floor within 3 mm under a 2 m straightedge.

This is for anyone about to lay glue down LVT on a floor that is not flat enough: a homeowner doing it themselves, or someone who wants to know what their fitter should be doing. It covers what self-levelling compound is, which type to use, how much to buy, how to mix and pour it, and how long to wait. Prices were checked on 11 November 2026 and include VAT. We do not sell compound or primer, so we name no brand: the bag you buy is the final word on its own figures.

Why LVT needs a flat floor

Glue down LVT is thin. Our own Daytona LVT range is 2.0 mm, and most glue down floors are 2.0 to 2.5 mm. It takes the exact shape of whatever it is stuck to. A ridge, a trowel mark or a dip that you cannot see in a bare room shows the first time low sun crosses the floor.

The UK standard for resilient floors, BS 8203, asks for no more than 3 mm under a 2 m straightedge. That is the figure to work to. Self-levelling compound (also called a smoothing compound, a leveller or, loosely, latex screed) is how you get there: a powder you mix with water, or with a latex liquid, that flows out into a flat, smooth skin a few millimetres thick.

Flat is not the same as level. A floor can slope gently from one wall to the other and still be fine. What matters is that there are no humps or hollows. Our subfloor preparation guide explains how to check, and the moisture tests to do first.

Do you need it at all?

Lay a 2 m straightedge (a long spirit level or a straight length of timber) across the floor in both directions and on the diagonals. Mark every place where a 3 mm gap opens under it.

A few small dips: fill them with a patching compound, let it dry and sand it smooth. You may not need to pour the whole floor.
Dips and humps all over, old adhesive, a rough screed: skim the whole floor. It is quicker than patching and looks better.
Click flooring: it is more forgiving, but it still needs a flat base, usually around 3 mm under 1 m. Check the product. Our glue down vs click guide explains the difference.

Which compound to use

Floor underneath	Compound to look for	Worth knowing
Concrete or sand and cement screed	Standard cement-based smoothing compound	The everyday case
Anhydrite (calcium sulphate) screed	A compound the maker rates for anhydrite	Sand off the surface skin first, and use the primer that maker names
Plywood overlay on timber	Fibre-reinforced or two-part latex compound	These cope with small movement in the timber
Old tiles or old adhesive	A compound the maker rates for it	Hollow tiles out first. Bitumen adhesive needs a special primer

Two-part latex compounds come as a bag of powder and a drum of liquid that you mix together. They are a little more flexible, which is why fitters use them over timber. Never pour any compound straight onto floorboards: overlay them with plywood first, screwed down at close centres, then level the ply if it needs it.

How much compound you need

Most compounds use about 1.5 to 1.7 kg of powder for every m² at every millimetre of depth. The bag gives the exact figure. Here is the working for a 15 m² room at an average depth of 3 mm:

15 m² x 3 mm x 1.5 kg = 67.5 kg
At 1.7 kg it is 76.5 kg
Either way that is 4 bags of 20 kg (80 kg)

Measure the depth properly. A floor that is 1 mm out at one end and 6 mm at the other averages more than you think, and running out halfway through a pour is the worst thing that can happen. Buy one bag more than the sum says: an unopened bag can usually go back to the merchant, a missing one cannot be fetched while the floor is setting.

Check the minimum and maximum depth on the bag as well. A skim thinner than the minimum can crack or turn to dust. Thicker than the maximum and you need two layers, or a deep-fill product.

What you need before you start

The compound, and the primer its maker names for your floor
Two large buckets, and a measuring jug or a bucket marked at the right water level
A paddle mixer on a strong drill
A steel smoothing trowel or a gauging rake
A spiked roller and spiked shoes, to work in the compound and let out air
Foam edge strip or tape for the walls, and a strip of timber to dam the doorway
A vacuum cleaner, a 2 m straightedge, and a helper if the room is over about 10 m²

Step by step

Check the floor is dry. On concrete and screed, under 75% RH with a hygrometer. On timber, 13% or less. Compound will not fix a damp floor. The subfloor guide has the tests.
Clean it. Scrape off old adhesive, paint and plaster. Then vacuum, do not sweep. Dust under compound is the most common reason it lets go.
Prime it. Use the primer the compound maker names, mixed and spread as their label says, and let it dry. Primer stops the floor sucking the water out of the compound, which causes pinholes and a weak bond. Most makers say not to use PVA instead.
Seal the edges. Fill gaps at the skirting and around pipes, run edge strip round the walls and fix a dam across the doorway. Compound finds every hole.
Get the room right. Most compounds want the room and floor above 5 to 10°C. Shut windows to stop draughts drying it too fast, and turn any underfloor heating off. The bag gives the range.
Mix one bag at a time. Water into the bucket first, then the powder, mixing with the paddle for the time the bag says, usually two or three minutes, until there are no lumps. Use exactly the water stated. Extra water makes it flow nicely and then dry weak and dusty.
Pour in strips. Start at the wall furthest from the door. Pour a strip about a bucket wide, spread it with the trowel, then pour the next bag against it while the first is still wet. A helper mixing while you pour keeps the edge wet. Most compounds give you about 20 to 30 minutes.
Roll it. Go over it with the spiked roller, in your spiked shoes, to work it into the floor and let the air bubbles out.
Leave it alone. Most compounds take foot traffic after a few hours. Do not glue anything to it until the bag says it is ready for floorcoverings.
Check it. Run the straightedge across it again. Sand off any ridges, vacuum thoroughly, and it is ready for the adhesive.

How long before you can lay LVT

For a typical cement-based compound at about 3 mm in a room at 20°C, about 24 hours is a common figure. Thicker layers, cold rooms and damp weather all take longer, and some fast-drying compounds take less. Work to the time on the bag, not to a fitter's diary. Glue down LVT on a compound that is still wet can blister, and the adhesive may never set properly.

If the floor has underfloor heating, follow the commissioning steps in flooring and underfloor heating before the floor goes down. Daytona is fine over heating up to a floor surface of 27°C.

What the floor on top costs

Once the compound is down, here is the rest of the bill for the same 15 m² room in Daytona Natural Oak plank, checked on 11 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 adhesive at £79.99.
Spreader: one A2 notched spreader at £9.95.
Total: £513.54 inc VAT, plus the compound and primer from your merchant.

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 sizes, use the flooring calculator and the LVT adhesive calculator. When the floor is ready, our guide to laying glue down LVT takes it from there.

Five mistakes that show through the floor

Too much water. It pours easily, then dries soft and dusty, and the adhesive pulls the top off.
No primer. The floor drinks the water, the compound pinholes and the bond is weak.
Running out mid-pour. A hard edge between two pours shows as a line under thin LVT. Buy a spare bag.
Too thin a skim. Under the bag's minimum depth it can crack. Fill deep hollows first, then skim.
Laying too soon. Wet compound under glue down LVT can blister the floor. Wait for the time on the bag.

Self-levelling questions people ask

How much does a 20 kg bag of self-levelling compound cover?

About 13 m² at 1 mm, 4.4 m² at 3 mm and 2.7 m² at 5 mm, if the compound uses 1.5 kg per m² per mm. Some use up to 1.7 kg, so check the bag and buy one spare.

Do I need PVA before self-levelling compound?

Use the primer the compound's maker names, not PVA. Most makers say PVA should not go under their compound. The right primer controls how fast the floor drinks the water and helps the bond.

Can I pour self-levelling compound over floorboards?

Not straight onto the boards. They move and leave gaps, and the compound cracks. Overlay them with plywood screwed down at close centres, then use a fibre-reinforced or latex compound on the ply if it still needs levelling.

Can I pour self-levelling compound over existing concrete?

Yes, that is what it is for. The concrete must be dry, sound, clean and primed. Loose or crumbly patches need cutting out and repairing first.

How long does self-levelling compound take to dry before LVT?

Often about 24 hours at 3 mm in a room at 20°C, but it depends on the product, the depth and the room. Thick layers and cold rooms take longer. The bag gives the time before floorcoverings: work to it.

Do I need self-levelling compound under click flooring?

Not always. Click is more forgiving and usually wants around 3 mm under 1 m, so small dips can be filled with a patching compound. Glue down LVT needs the whole floor within 3 mm under 2 m.

Next steps

Read the standards and moisture tests in our subfloor preparation guide.
Order up to five free samples to see the floor before you prepare for it.
Browse the Daytona range and flooring adhesive.
New to LVT? Start with the LVT buyer's guide.

Written by Flooring Monster. Facts and prices checked 11 November 2026. Flatness and moisture figures are from BS 8203; compound figures are typical, so always follow the bag of the product you use. Questions? Call us free on 0800 870 8795.