PVC Flooring Installation: 3 Substrate Checks You Must Pass

When commercial PVC flooring develops hollow spots, curling or open seams within the first six months, the culprit is usually the substrate, not the flooring itself. Resilient vinyl is a thin-bond installation: how good the base is decides how long the floor lasts. This article explains the three hard substrate checks so contractors and buyers can verify them before laying a single sheet.

1. Flatness: within 3 mm under a 2 m straight edge

An uneven base produces a wavy surface, lipped seams and creaking underfoot. The check is simple: run a 2 m straight edge with a feeler gauge across the room in several directions — the gap between the straight edge and the floor should stay within 3 mm, and stricter in high-traffic areas.

If the floor fails, level it with self-leveling compound instead of patching thick adhesive. Wait until the compound is fully dry and cured before moving on, otherwise it settles and cracks later.

2. Substrate strength: no dusting, no shelling, no cracks

A weak cement base shows up most clearly as "dusting" — rub it and powder comes off; scratch it with a key and a groove appears. Bonding adhesive cannot hold on such a base, and the floor will eventually hollow. Check three things:

• No dusting: the surface should not shed sand when scratched, and should not lose powder under abrasion.
• No shelling: tapping with a hammer or hard object should not produce a hollow "drum" sound — the surface layer must be firmly bonded.
• No cracks: no through cracks on the surface; treat hairline cracks first and reinforce cracked areas.

3. Moisture content: keep cement bases at or below 3%

Moisture is the most overlooked check and the most damaging. Rising moisture softens the adhesive and causes blistering, mold and curled seams. Acceptance standard: moisture content of cement mortar or concrete bases should be ≤3% (measured at multiple points with a moisture meter). For heated floors, run a pre-heating and dehumidifying cycle first according to the underfloor heating specification.

If moisture is above the limit, a few days of airing is usually not enough — apply a primer or a moisture barrier as recommended by the manufacturer, and re-test before installation.

4. Site conditions also matter

Beyond the three substrate checks, on-site conditions on the day of installation affect the final result:

• Temperature and humidity: install at 15°C or above with moderate humidity; let the flooring and adhesive acclimatize in the room for about 48 hours beforehand.
• Cleanliness: the base must be free of dust, oil and loose debris; vacuum and dust before applying adhesive.
• Movement joints: treat existing expansion and settlement joints properly — never lay flooring straight across them.

Doing the substrate checks first means the PVC floor lays flat, bonds firmly and lasts. Gulin Trading supplies Armstrong, Gerflor, LX Hausys and other branded PVC and rubber flooring, with full technical support from material selection to base requirements and installation guidance. For selection or installation advice, call 0512-68114680.