Level a concrete floor before laying new flooring

Clear, check and smooth a concrete floor with self-levelling compound so new flooring lies flat.

FL-01Clear the roomRemove furniture, rugs, and any old flooring down to bare concrete. Lift skirting boards if you want a neat edge, numbering each length so it goes back in the same place. Sweep and vacuum so you can see the floor properly.

1 each · Flat pry bar

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2 each · Dust sheet

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FL-02Check for asbestos before disturbing old adhesive or tilesIf your home was built or floored before 2000 and the concrete has old vinyl tiles, lino, or black bitumen adhesive stuck to it, stop before you scrape, sand or grind it. Get a sample tested, or use a licensed asbestos contractor if you're not sure. Only carry on with grinding in the next steps once you know it's safe.

RULES

1 each · Asbestos test kit

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KNOW THE RULES

Under the Control of Asbestos Regulations 2012, you must not disturb suspected asbestos-containing materials yourself. Older flooring adhesives and tiles (pre-2000) can contain asbestos and need testing or a licensed contractor.

FL-03Check the floor for damp and movementPress a damp meter onto several spots, especially near external walls and in corners. Look closely at any cracks - if they're wide, flaking, or seem to be moving, get advice before covering them up, as levelling compound alone won't fix a structural problem.

1 each · Digital damp meter

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FL-04Find hidden pipes and cables before you grind or chaseConcrete floors can hide underfloor heating pipes, electric cables, and old central heating pipework anywhere, not just near walls. Sweep a cable and pipe detector over the whole area, but still treat every spot as live until you've proved it isn't - detectors miss deep or shielded services. Find your stopcock (usually under the kitchen sink) and check it turns before you start, so you can shut the water off fast if you hit a pipe. If you have any doubt, isolate the relevant circuit at the consumer unit before grinding or chasing into the floor.

1 each · Cable and pipe detector

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FL-05Grind down high spots and ridgesUse an angle grinder fitted with a diamond cup wheel to knock back high points, ridges, or lumps of old adhesive. Work slowly and check with a straightedge as you go. Wear a dust mask and eye protection - concrete dust is unpleasant to breathe and gets into everything.

1 each · Diamond cup wheel

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1 pack · Dust mask (FFP3)

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1 each · Safety goggles

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FL-06Fill cracks, holes and low spotsRake out any loose or crumbling material from cracks and holes. Fill them with a flexible floor repair mortar, pushing it in fully so there's no trapped air. Let it cure fully before continuing - check the tin, usually a few hours - or you'll trap moisture under the levelling compound.

1 tub · Flexible floor repair filler

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FL-07Vacuum and prime the floorVacuum thoroughly, getting right into edges and corners. Brush or roll on a floor primer, diluted as the tin says, covering the whole area evenly. Leave it to dry fully - usually 1 to 4 hours - it stops the self-levelling compound drying too fast and cracking.

1 each · Floor primer 5L

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1 each · Paint roller

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FL-08Mix the self-levelling compoundMix one bag at a time in a clean bucket using a paddle mixer on a drill, following the water ratio on the bag exactly - too much water weakens it. It starts setting within minutes, so only mix as much as you can pour and spread straight away.

3 each · Self-levelling compound 20kg bag

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1 each · Mixing paddle attachment

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1 each · Mixing bucket

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FL-09Pour and spread the compoundPour in bands starting from the far corner, working back towards the door. Use a levelling spreader or trowel to even it out - it's mostly self-levelling but a little help stops thick and thin patches. Run a spiked roller over the wet surface to release trapped air bubbles.

1 each · Levelling compound spreader

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1 each · Spiked roller

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FL-10Leave to cure and check for flatnessLeave the floor undisturbed for the time given on the bag - usually about 24 hours before walking on it, and longer before laying flooring or fitting anything heavy. Once cured, check flatness with a long straightedge; lightly sand off any tiny high points.

1 each · Straightedge 1.8m

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FL-11Tidy upBag up rubble, empty bags, and dust for disposal. Check with your council before putting a lot of rubble in general waste, as some won't take it. Wipe tools clean before any leftover compound sets hard on them.

3 each · Heavy-duty rubble bags

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PART OF A BIGGER PROJECT

Prepare a room for new flooring · Lay vinyl flooring in a kitchen or bathroom · Lay laminate flooring through a room

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