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Vinyl flooring can only perform as well as the surface beneath it. At Western Distributors, we often see how careful subfloor preparation leads to a smoother finish and a longer lasting floor. This guide explains how to check moisture, repair cracks, level uneven areas and clean a concrete slab properly, so your new vinyl looks great and stays that way.
Vinyl is thin and flexible compared with timber or tiles. That makes it comfortable underfoot and easy to install, but it also means it can reveal almost every flaw in the surface below. Small bumps, trowel marks and grit can show through as ridges or dents over time.
Moisture is the other major risk. Excess moisture in a slab can weaken adhesives, cause bubbling or lifting, and lead to mould beneath the floor. Good preparation prevents these problems before they start.
In Australia, the installation of resilient floor coverings such as vinyl is guided by AS 1884, the Australian Standard for resilient floor coverings. It sets out requirements for subfloor condition, moisture testing and installation practice.
Start by understanding the slab you are working with. New slabs hold a large amount of water from the concrete mix, and they need time to dry before vinyl can be laid.
Drying is not always simple to predict. Research published in the Journal of Building Engineering found that relative humidity readings inside concrete change with temperature, even when no moisture has been lost. This is one reason professional testing is more reliable than guesswork.
Older slabs bring different issues, such as old adhesive, paint, sealers or cracks. Walk the floor and note:
Moisture testing is the step that should never be skipped. According to ATTAR, the 2021 update to AS 1884 made the in situ relative humidity probe test the only normative method, and reduced the equilibration period from 72 hours to 24 hours after sensor placement.
In simple terms, small holes are drilled into the slab, probes are inserted, and the readings show how much moisture remains inside the concrete. Relative humidity should generally be below 75 percent before resilient flooring is installed, otherwise adhesives may fail and moisture can be trapped beneath the floor.
If readings are too high, options may include:
Vinyl needs a clean surface for strong adhesion. Remove any existing carpet, underlay, tiles, paint or loose coatings. Old adhesive residues should be scraped or ground back so they do not react with new products or leave ridges.
Also look for oil, grease and curing compounds, particularly in garages or older commercial spaces. These can stop adhesives and levelling compounds from bonding properly.
Mechanical grinding removes high spots, ridges and stubborn residues. It also opens up the concrete surface so primers and levelling compounds can bond.
Grinding concrete creates respirable crystalline silica dust, which is a serious health hazard. WorkSafe Victoria sets the workplace exposure standard at 0.05 mg/m³ over eight hours and recommends on tool water suppression or dust extraction connected to a Class M or H vacuum. Dry sweeping and compressed air should never be used for clean up.
The scale of the risk is significant. Lung Foundation Australia warns that more than 600,000 Australian workers are at risk of silica dust exposure across construction and related industries. If you are not equipped to control dust properly, this stage is best left to professionals.
Cracks, chips and holes should be filled with a suitable repair product before levelling. Concrete slabs naturally shrink and can curl slightly as they dry. Research by Professor Ian Gilbert of UNSW, published in the Electronic Journal of Structural Engineering, explains that drying shrinkage is greatest at the surface, which can create internal stresses and movement over time.
For flooring, this means small cracks are common. However, large, active or widening cracks may point to structural movement and should be checked by a qualified professional before any flooring goes down.
Once repairs are complete, the slab needs to be flat and smooth. The general process is:
Industry bodies play an important role in setting these expectations. The Australian Resilient Flooring Association, the peak body for resilient floor and wall coverings, works with the Vinyl Council of Australia to support best practice across the sector.
Before installation, vacuum the slab thoroughly to remove all dust and grit. Even small particles can create bumps under thin vinyl.
Most vinyl products also need time to adjust to room conditions before installation. Follow the manufacturer’s guidance on temperature and acclimatisation. Keeping the room at a stable temperature helps the vinyl and adhesive perform as intended.
If you are still deciding on a product, explore vinyl flooring range in Melbourne at Western Distributors, which includes timber look, tile look and commercial options.
Many vinyl flooring problems can be traced back to a few preparation shortcuts:
Wet areas deserve extra care. Avoid the biggest mistakes people make with bathroom flooring and know what to watch for in bathrooms and laundries.
A well prepared concrete subfloor is the foundation of a beautiful, long lasting vinyl floor. By testing moisture, repairing damage, levelling carefully and keeping the surface clean, you give your new flooring the best possible start. For expert advice and quality vinyl flooring in Melbourne, contact us today, and our team will help you choose the right product.
Can vinyl flooring be laid directly on concrete?
Yes, provided the concrete is dry, clean, flat and smooth, and prepared according to the manufacturer’s instructions.
How do you check if a concrete slab is dry enough for vinyl?
An in situ relative humidity probe test is the recommended method under AS 1884 for resilient floor coverings.
Do I need to level concrete before laying vinyl?
Yes. Vinyl can show bumps and dips, so uneven areas should be ground or levelled beforehand.
Do you need underlay for vinyl on concrete?
Glue down vinyl does not use underlay, while some click systems include or recommend one. Check product instructions.
How long should a new concrete slab dry before vinyl?
Drying time varies with slab thickness, weather and ventilation, so moisture testing is the only reliable guide.
What happens if vinyl is laid on damp concrete?
Moisture can weaken adhesives, cause bubbling or lifting, and encourage mould growth beneath the flooring.
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