How to level a floor: step-by-step DIY guide

A level subfloor is the foundation for laminate, tiles or another floor finish. With the right primer, levelling compound and a clear plan, you can level a floor yourself. This DIY guide walks you through it step by step, from preparing the substrate to waiting before you continue.

What do you need to level a floor?

Which materials do you need?

• A self-levelling compound that suits your subfloor and the required layer thickness, such as Flowtech Easy or Keralevel Eco. Which product you choose depends on the substrate and the job; always follow the packaging.
• A primer that suits your substrate, such as Primer Uni or a deep penetrating primer for highly absorbent substrates.
• Optionally a repair mortar or filler for cracks, holes and gaps (follow the packaging of the product you choose).
• Masking tape or edge strips to protect walls, frames and doorways.

Which tools do you need?

• A drill with a mixer for adhesive and plaster and a sturdy bucket.
• A smooth stainless steel trowel to spread the compound and work it into corners. You will find more trowels under smooth and toothed trowels.
• A long spirit level (and optionally a straight batten) to measure unevenness, plus a tape measure.
• A broom, vacuum cleaner and optionally a soft brush or roller for the primer.
• Protective gear: nitrile-coated work gloves, safety glasses, knee pads, safety shoes and sturdy workwear. Choose your own size. When mixing powder products, an FFP3 dust mask is wise.

How do you prepare the floor?

The substrate must be clean, dry, sound and free of dust. Remove old floor coverings and skirting where needed. Sweep and vacuum thoroughly, and degrease oily spots. Fill cracks, holes and gaps (including at walls and around pipe penetrations) so the compound cannot run away. Let repairs cure as stated on the packaging.

Measure unevenness with a long spirit level or straight batten in several places. The highest point of the floor largely determines how thick your levelling layer needs to be: you fill the low spots up to that level. Then calculate consumption using the packaging of your compound.

Prime the floor. Primer improves adhesion, controls absorbency and helps prevent air bubbles. On highly absorbent or very smooth substrates, the right primer matters even more. Apply it evenly and let it dry as stated on the packaging. Then mask edges, frames and doors.

Do you have underfloor heating, large height differences, a doubtful substrate or a large room? Ask a professional for advice. Levelling takes pace and experience; in risky situations a tradesperson makes the difference.

How do you level a floor, step by step?

1. Make a work plan. Levelling compound has a limited working time. Ideally work with two people: one mixes, the other pours and spreads. Start at the far end of the room and work towards the door so you do not get trapped.
2. Get materials ready. Keep clean water, enough bags of compound, mixer, bucket, trowel and protection within reach. Read the packaging once more before you start.
3. Mix the levelling compound. Follow the mixing ratio on the packaging. Put water in the bucket first, then add the powder. Mix with the drill and mixer until smooth and lump-free. Mix no more than you can use within the working time. Rinse the mixer straight away.

4. Pour the compound. Pour in strips across the floor, from the farthest corner towards the door. Work wet-on-wet: new batches must join compound that is still wet.
5. Spread with the smooth trowel. Guide the compound into corners and edges with the smooth trowel. Self-levelling compound mostly flows on its own, but you still need to steer it so no bare spots remain.
6. Release air bubbles. Air bubbles often rise while you spread. Stroke gently with the trowel and let the compound continue to flow. (A spiked roller helps, but is not always essential; if you do not have one, work carefully with the trowel.)
7. Check for flatness. After application (and again after drying) lay the spirit level in several places. You want an even, flat surface without dips or bumps; the floor does not have to be perfectly level to the world, but flat enough for your finish.
8. Allow drying as stated on the packaging. Wait for the stated drying and walk-on times before you lay laminate, tiles or another floor. Timing depends on the product, layer thickness and climate. Always follow the packaging.

What mistakes do DIYers often make?

• Skipping or using the wrong primer. The substrate then absorbs too hard or the compound bonds poorly.
• Adding too much water. That weakens the compound and increases the risk of cracking or dusting. Stick to the mixing ratio on the packaging.
• Mixing too much at once. Compound that has already started to set no longer flows well.
• Forgetting holes and gaps. The compound then runs into voids or towards the neighbours below.
• Continuing too soon. Laminate or tiles on compound that is still too wet cause problems. Wait until the packaging allows it.

💡 Tip: practise first in a small room or make a test strip, so you learn the pace of mixing and pouring before you tackle a large room.

How do you level a floor safely?

Levelling compounds and primers are construction chemicals. Powder products can release dust; wet mortar is often alkaline and can irritate skin and eyes. So wear nitrile-coated gloves, safety glasses when mixing, and for dust an FFP3 dust mask. Wash your hands after work.

Knee pads spare your joints when you work on the floor. Safety shoes protect your toes if a bag or bucket falls, and sturdy workwear keeps splashes off your skin. You will find all personal protective equipment in our workwear and safety range. For more tips, read our guide to safe working on the construction site.

What do DIYers often ask about floor levelling?

Do I always need to level before laminate or tiles?

Not always, but unevenness shows through the finish and can stress laminate or tiles. With noticeable bumps or dips, levelling is wise. See also our blogs on laying laminate and tiling a floor.

How thick should the levelling layer be?

That depends on the unevenness and on the product. Measure the height difference and check the packaging for the minimum and maximum layer thickness allowed.

Can I level over existing tiles?

Sometimes, if the tiles are firmly fixed and flat. Clean and degrease them and use a primer suitable for non-absorbent substrates. In doubt? Ask a professional for advice.

When can I continue with laminate or tiles?

Only once the compound has dried enough according to the packaging. That time differs per product and layer thickness.

What about underfloor heating?

Follow the instructions from both the compound manufacturer and the underfloor heating system. The heating often needs to be off or lower for a while. If in doubt, call in a professional.

When should I call in a professional?

For large unevenness, moisture problems, doubt about the substrate, underfloor heating, or if you do not trust the pace of levelling. A tradesperson prevents costly repairs; they are not an optional extra on difficult floors.

Where can you find everything to level your floor?

At Saniso, the online DIY store for building and renovating, you will find levelling compounds, primers, tools and protective gear for this job.

• Browse Flowtech Easy, Keralevel Eco and Primer Uni.
• Find the right construction tools and workwear and PPE.
• Create a customer account and order with ease.
• Working on a larger project? Request a project quote.
• Book a showroom visit in Zwaag, at least 24 hours in advance.
• Not sure which material suits your job? Get in touch with us.

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