Self-levelling floor in Batumi for laminate, SPC vinyl and tiles

Self-levelling floor and screed: the difference

Screed sets the height of the floor: it is poured to guide rails in a layer several centimetres thick, and pipes, cable or soundproofing are hidden inside it. A self-levelling floor goes over the screed in a layer a few millimetres thick and brings its surface to a flat plane. The mix flows out by itself, and small waves, straightedge marks and pits disappear under a smooth surface.

We pour self-levelling floors in Batumi from cement-based mixes. The same name is used for polymer coatings based on epoxy resin, which become the finished floor themselves, but in apartments they are rarely ordered. Here we mean a levelling layer under a floor covering, and work with a thick base is described on the page about floor screed to guide rails.

When a self-levelling layer is needed, and when it isn't

• Under glue-down vinyl flooring it is needed almost always: thin vinyl follows every bump, and by the window, in light falling at an angle, it shows at once.
• Under laminate and click SPC vinyl we pour it if the gap under a two-metre straightedge is more than 2 mm. With a smaller gap the screed is already within tolerance, and laminate laying goes straight onto it.
• Under porcelain floor tiles in 60×60 and 60×120 formats we level when the screed wanders by a few millimetres: a wave like that can't be taken out with a thick bed of adhesive.
• After old tiles are removed, we fill the pits and the adhesive residue, if the screed under them is sound.

A thin layer can't strengthen a weak base: if the top of the screed crumbles or sounds hollow, the new layer will come away together with it. A level difference of more than 3 cm is also more honestly dealt with by screed than by pouring centimetres of expensive mix.

Preparing the base: strength, moisture, primer

The mix holds on to the screed, so first we check the screed itself: we scratch the top with a nail, tap it and measure its moisture with a moisture meter. We take the screed age required before pouring from the mix's data sheet, and for cement-based products it is usually at least 28 days. With developer's screed in a white frame apartment the pouring date is usually unknown, so we measure moisture at several points, including by the external wall.

We grind off a weak top and the laitance, open up and fill cracks, and remove the dust with a vacuum cleaner. Then we prime in one or two coats, depending on how much water the base absorbs. Primer seals the pores: otherwise the mix thickens before it has flowed out, and air from the screed rises through it and sets as craters. Along the walls and around pipes and columns we fix a perimeter strip, so that the layer doesn't butt against them and crack at the edge.

How we pour: levels, mixing, rolling

With a laser level we take readings across the whole area and set level pins to the height of the future layer. We calculate the thickness from the highest points of the screed: there the layer must be no thinner than the minimum on the mix's data sheet, usually 2–3 mm.

We mix with a paddle mixer and measure out the water for each bag according to the data sheet. Extra water thins the mix: the heavy filler settles, a weak film is left on top, and later it dusts and flakes under the floor covering. We pour in strips without a break, so that each new batch meets the still-liquid edge of the previous one, and immediately go over it with a spiked roller: it lets the air out and spreads the mix. Consumption on the data sheet is usually 1.5–1.8 kg per m² per millimetre, so a 5 mm layer over 40 m² takes 300–360 kg, or 12–15 bags of 25 kg.

Drying, and when to lay the floor covering

You can walk on a thin layer after a few hours, but the floor covering goes down later, after the time given on the mix's data sheet. For ordinary cement-based mixes it grows with the thickness: about three days for a layer up to 10 mm, a week for 10–30 mm and two weeks for 30–60 mm. These times are calculated for a warm, dry room, so in the wet months we go by the moisture meter, not the calendar.

A fresh layer doesn't need watering like screed: there is enough water in the mix, and the main thing is not to let draughts dry it out. For the first day we keep the windows closed and the layer out of the sun, and we don't point a space heater at it, otherwise the top dries before the body of the layer and a network of cracks appears. We start airing and running a dehumidifier on the second day.

How much a self-levelling floor costs in Batumi

Pouring a self-levelling floor costs from 14 to 18 ₾ per m², and that is labour only. The mix is priced separately: in our table it is 21–30 ₾ per m² at a normal layer thickness, and a thick layer needs more of it. If the screed needs grinding and repair, the preparation goes into the estimate as separate lines.

For comparison, screed to guide rails costs 40–66 ₾ per m² in labour plus another 30–42 ₾ for the mix at a 5 cm layer. So where a thin layer is enough, that is what we offer, and where the level difference is large, we price screed. Laying SPC vinyl over a self-levelling floor costs 25–36 ₾ per m². The final cost is set after measuring with a laser level and agreeing the estimate.

How we accept a self-levelling floor

We accept the layer once it has dried to the floor covering's moisture limit. We place the two-metre straightedge in several directions: under laminate and click SPC vinyl we allow a gap of up to 2 mm, and under glue-down vinyl no more than 1 mm. We tap the whole area and run a palm over the top: the layer must not sound hollow or leave dust on the hand. The straightedge and moisture readings go into the certificate with photos, and you see them before the floor covering goes down.