Best Self Levelling Compound for Uneven Floors: 2025 Expert Review
DR Joinery
Expert Joiner & Flooring Specialist
If you have ever tried to lay a solid oak floor over an uneven substrate, you will know the pain of 'bounce' and squeaking boards six months down the line. In York, where our housing stock is predominantly older, finding a dead-level floor is about as likely as finding a straight wall in a farmhouse.
Proper subfloor preparation is the difference between a professional finish and a DIY disaster. Whether you are working with a suspended timber floor or an old concrete slab, a quality self levelling compound is often the only way to ensure your expensive hardwood sitting flat and secure.
In this review, I'm looking at three products available this year: a standard compound for concrete, a flexible screed essential for timber substrates, and a mechanical aid for checking levels during the process.
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Specs vs. The Real World
The Spec: "'Self-Levelling'"
"You simply pour the mix onto the floor, and gravity creates a glass-smooth surface without any effort."
The term is a bit of a misnomer. You still need to help it simply with a trowel, especially towards the edges. If you don't agitate it to release trapped air (using a spiked roller), you will end up with bubbles and ridges.
The Spec: "Drying Time (2-4 hours)"
"You can walk on it and lay flooring the same afternoon."
In a cold, damp Yorkshire terrace, drying times can double. Whilst it might take foot traffic in 4 hours, moisture content must be fully consistent before laying expensive oak on top, or the timber will cup. Always leave it overnight at minimum.
My Top 3 Recommendations
Three options to cover different needs and budgets
Yhsioaklo Floor Leveling Compound for Tile - 40Pcs Leveler Tile Tools
Yhsioaklo
It is important to clarify that this is not a pourable compound, but a mechanical alignment tool. However, for budget-conscious renovations involving both tiling and flooring thresholds, keeping levels consistent is vital. This kit is a cost-effective way to ensure your adjacent tiled surfaces are flat before we join the timber flooring to them.
The Good
- Reusable pins save money on future projects
- Helps ensure perfectly flat transitions where tile meets timber
- Simple to use, even for DIY enthusiasts
The Bad
- Not a pourable screed/compound (misleading title)
- Steel pins can snap if the adhesive sets too hard before removal
Installer Tip:
If you are tiling a hallway that leads into a room where we are fitting hardwood, use these clips to get the tile edge perfectly flat. It makes fitting the threshold later much tidier.
Priced at £13.39 at the time of writing
Check Price on AmazonBostik Cempolay Self-Levelling Compound for Interior Floors, Colour: Grey, 25kg
Bostik
Bostik is a name we trust in the trade. This standard Cempolay is a fantastic general-purpose compound for smoothing out rough concrete or sand/cement screeds often found in ground-floor extensions. It flows well and feathers out nicely at the edges, creating a reliable base for glue-down or floating hardwood floors.
The Good
- Excellent flow properties - truly 'self-smoothing'
- Protein-free formula suitable for hygiene areas
- Can be feathered to a very thin edge
The Bad
- Not flexible - avoid using over timber floorboards
- Interior use only (standard for hardwood prep)
Installer Tip:
Always prime the subfloor with a suitable acrylic primer before pouring. If you don't, the dry concrete will suck the moisture out of the mix too quickly, leading to pinholes and a weak surface.
Priced at £25.14 at the time of writing
Check Price on AmazonBond It LEVELMASTER 200 Flexible Self-Levelling Floor Compound
Bond It
This is the 'problem solver' for joiners. Because it is polymer-modified, it has flexibility that standard screeds lack. This makes it perfect for use over plywood overlays or floors with underfloor heating, which is increasingly common in York renovations. It mimics the movement of the substrate rather than cracking.
The Good
- Flexible formula prevents cracking on timber overlays
- Compatible with underfloor heating systems
- Single part mix - just add water (no latex bottle needed)
The Bad
- Slightly trickier to trowel smooth than standard latex
- Must ensure floorboards are rigidly fixed before application
Installer Tip:
If you are using this over timber, ensure every loose board is screwed down tight first. Even a flexible compound can't handle a loose floorboard rocking underneath it. I always recommend over-boarding with 6mm or 9mm plywood before pouring this compound.
Priced at £19.89 at the time of writing
Check Price on AmazonFrequently Asked Questions
Can I pour self levelling compound directly over floorboards?
How do I calculate how much compound I need?
Why has my self levelling compound cracked?
What is the difference between 'trade' and 'DIY' compounds?
Does DR Joinery undertake subfloor preparation?
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