What preparation does LVT require?

LVT needs a subfloor that is flat, sound, clean and dry. Over concrete that often means a moisture check and a primed smoothing compound; over timber it usually means a plywood overlay. Glue-down LVT also needs a dust-free surface the adhesive can bond to. Poor preparation is one of the most common reasons an LVT floor looks or wears badly.

LVT (luxury vinyl tile) is thin and fairly flexible, so it takes on the shape of whatever is underneath it. That is why preparation is often the biggest variable in an LVT job, and why it is usually itemised separately on a quotation.

Why does LVT need such a flat subfloor?

Any ridge, hollow, lump of old adhesive, nail head or board edge can show through LVT as a visible line or bump, particularly in low light from a window. High spots also take more wear, so they can scuff sooner than the rest of the floor.

A base that is fine for carpet is often not flat enough for LVT, because carpet and its underlay hide a lot. Flatness tolerances vary by product. Many manufacturers ask for something in the region of no more than 3 mm deviation under a 2 m straightedge, and some ask for tighter. The installation instructions for the specific product are the figure that matters.

How is a concrete or screed floor prepared for LVT?

Typical steps on a solid floor:

• Moisture check. Concrete and sand and cement screeds can hold moisture for a long time. In the UK, resilient flooring is generally installed in line with BS 8203, and the usual approach is a hygrometer test, with many manufacturers and adhesive suppliers asking for a reading of 75% relative humidity or lower before laying. If the floor is wetter than that, a surface damp-proof membrane may be needed, or the job may need to wait.
• Removing what shouldn’t be there. Old adhesive, paint, plaster splashes and loose material are scraped or ground off so the new layers bond properly.
• Repairs. Cracks, holes and damaged areas are filled.
• Priming and smoothing. A primer is applied, then a smoothing compound (often called self-levelling or latex) is poured to give a smooth, flat surface. A thickness of around 3 mm is commonly used under LVT, more where the floor is uneven. The compound must dry before the LVT goes down; drying times depend on the product, depth and room conditions.

Anhydrite (calcium sulphate) screeds, which are common with underfloor heating, have their own rules, including removing the surface laitance and using compatible primers. If you know what type of screed you have, mention it when you ask for a quote.

How is a timber floor prepared for LVT?

LVT is not usually laid directly onto floorboards, because the gaps, cupping and movement in the boards will show through. The common approach is:

• Securing the boards. Loose or squeaky boards are fixed down and damaged boards replaced.
• Plywood overlay. A plywood suited to flooring is fixed over the boards at close centres to give a flat, stable surface. Around 6 mm is a common thickness, but the right sheet and fixing pattern depend on the floor and the LVT manufacturer’s instructions.
• Chipboard decking. Upstairs in many newer homes the floor is chipboard sheet. If it is sound, flat and well fixed it may need only minor work, but joints and any damaged areas still need attention.

Suspended timber floors also need to stay ventilated underneath, so airbricks shouldn’t be blocked. For more on timber floors, see laminate over floorboards, which covers similar issues.

Click vs glue-down LVT: does the preparation differ?

Both need a flat, sound base. The differences are in the detail:

• Glue-down LVT bonds directly to the subfloor, so the surface has to be clean, dust-free and compatible with the adhesive. It shows imperfections most readily, and is often chosen for larger areas and for use over underfloor heating.
• Click LVT is usually laid as a floating floor, sometimes with a pre-attached underlay and sometimes with a separate underlay specified by the manufacturer. Rigid-core click products can bridge very small imperfections, but they still need a flat base or the joints can be stressed.

Over concrete, many click LVT products also call for a moisture barrier. The click vs glue-down LVT comparison sets out the pros and cons of each.

Does LVT need acclimatising?

Most manufacturers ask for LVT to be left in the room where it will be fitted for a period beforehand, commonly around 24 hours, with the room kept within a stated temperature range before, during and after fitting. See acclimatisation. Follow the specific product’s instructions, as they do vary.

What about underfloor heating?

LVT can be used with many underfloor heating systems, but manufacturers typically set a maximum floor surface temperature (often around 27°C) and ask for the system to have been commissioned and run before the floor is laid, then turned down around fitting. Check both the heating and the flooring guidance.

New-build floors

New concrete and screed hold construction moisture and can take months to dry, so a recently built ground floor is a common reason for a failed moisture test. See when to install flooring in a new-build for timing.

Common questions

Can LVT go straight onto concrete?

Only if the concrete is dry enough, flat enough and sound. Most concrete floors need at least some repair and smoothing before glue-down LVT, and a moisture test is sensible on anything recent.

Can LVT be laid over existing vinyl or tiles?

Sometimes, if the existing floor is well bonded, flat and the manufacturer allows it. Cushioned vinyl is generally not a suitable base. Grout lines in tiles usually need filling or smoothing so they don’t show through.

Why is preparation priced separately?

Because it can’t be known until the subfloor is seen. Two rooms of the same size can need very different amounts of work, which is why a home measure is the point where preparation is confirmed.

Next step

If you are planning LVT in Burton-on-Trent or nearby, ask for an LVT estimate or request a home measure so the subfloor can be assessed and any preparation written into your quotation.