Self-levelling compound before vinyl: when it is needed

Vinyl is thin and flexible, which is part of its appeal. The downside is that it shows what is underneath. Dips, ridges, trowel marks and cracks in a slab can all come through as visible lines, soft spots or gaps between planks. Self-levelling compound is one of the main ways we create a flat surface before vinyl goes down. Here is when it is needed and what it involves.

What self-levelling compound is

Self-levelling compound is a cement-based product mixed with water and poured over a prepared floor. It flows out under its own weight and, with a little help from a spreader and spiked roller, settles into a smooth, flat layer. Depending on the product, it can be applied thinly to smooth a surface or built up to fill low spots. Once cured, it gives the vinyl a consistent base.

Signs your floor may need levelling

• Visible dips or humps when you lay a long straight edge on the floor
• Old tile adhesive ridges after tiles have been removed
• Patchy concrete repairs or old trench lines
• A junction between an old slab and a new extension that does not line up
• Glue-down products specified over a slab that is not flat enough for them

Manufacturers specify how flat the subfloor must be for their products. Click-lock planks and glue-down vinyls have different tolerances, and sheet vinyl tends to be the least forgiving. We check against the requirements for the product you have chosen.

What happens before the pour

Self-levelling compound needs a sound, clean surface to bond to. Before it goes down we usually need to remove old adhesives, paint or loose material, often by grinding, then vacuum the surface and apply a primer. Cracks and joints may need treatment first. Thresholds and drains are dammed so the compound stays where it should.

Moisture comes first

Levelling compound does not fix moisture problems. If a slab is giving off too much moisture, it can affect the compound, the adhesive and the vinyl. We assess moisture before levelling and, where needed, recommend a moisture-mitigation system first. Getting that order wrong is one of the main reasons floors fail early.

Drying times and your program

Every product has its own drying and curing times, which depend on thickness, temperature and ventilation. Thin applications may be ready relatively soon, while thicker builds take longer. We will tell you what to expect for your job and plan the vinyl install accordingly. Rushing a floor onto damp compound saves a day and risks the whole job.

How it shows up on a quote

Levelling is quoted separately from the vinyl because it depends on the condition of your slab, not the product you choose. A quote that shows no preparation on an older home or a slab with tiles removed deserves a question. We list grinding, priming, levelling and moisture treatment as separate items so you can see what each one costs and why it is needed.

Timber floors are different

Self-levelling compound is mostly used on concrete. Timber subfloors usually need different preparation, such as fixing loose boards, sanding high spots or installing a suitable underlay sheet, depending on the product. We advise on the right method after seeing the floor.

When levelling is usually needed

• Floor checked with a straightedge or level against the product tolerance
• Moisture assessed where it's required
• Surface cleaned and primed before the pour
• Drying time confirmed and built into the program

Ask for a measure

The best way to know whether your floor needs levelling is an on-site check. Request a free quote and 8K Flooring Group will assess your subfloor and give you an itemised price. We are based at 14 West Court, Coolaroo VIC 3048 and work across Melbourne’s north and metro area.