5.5mm SPC Flooring - Stone Plastic Composite Plank for Homes and Apartments

5.5mm is the gauge that most SPC flooring is actually made in. It sits in the middle of the range, carries the largest stock of colours, and on a residential project with no height constraint it answers more questions than any other thickness. The plank is a rigid core of limestone powder and virgin PVC resin, with a printed decorative layer on top and a click profile cut into all four edges.

A 4.5mm board exists for a reason and a 7mm board exists for a reason. The 5.5mm sits between them and is wrong for neither, which is exactly why it ships in the greatest volume. The useful question is not whether thick is better. It is which one millimetre buys you something on a specific job, and on most residential jobs it does.

1220 x 183mm planks in 5.5mm. The rigid core carries the click profile on all four edges, so the joint holds without adhesive.

These are the two gauges that get argued about on site, and the argument is usually settled by one question: is there anybody living below the floor?

On a ground floor in a house, the extra millimetre buys very little and the thinner gauge is the sensible order. On the third floor of an apartment block with a tenant below, the calculation reverses completely, and the reason is not durability. A 4.5mm floor will wear just as well as a 5.5mm floor if the wear layer is the same. What it will not do is carry the acoustic performance that a multi-unit building usually requires, and that is a specification problem rather than a cost one.

Noise complaints between floors are almost never about the floor covering on its own. They are about the whole assembly, and the floor covering is only the top layer of it. Still, that top layer is the one the buyer specifies, so it is worth understanding what it can and cannot contribute.

Three things in the assembly drive the impact noise result, and they stack. The first is the mass of the core, which is where the extra millimetre of a 5.5mm board contributes. The second is the backing layer, usually IXPE foam, which decouples the floor from the substrate so vibration is absorbed rather than transmitted. The third is the substrate itself, because a suspended timber floor behaves very differently from a concrete slab.

This is the practical reason 5.5mm outsells 4.5mm in apartment work even though both are stocked. More core mass plus a pre-attached backing gives the installer more headroom against a performance target, and headroom is worth paying for when the alternative is a failed acoustic test after the floor is down. The question of when underlayment is actually needed is covered separately, and it is worth reading before assuming a backing can be added later.

A rigid core does not bend to follow a dip in the substrate. It bridges it or it rocks on it. How large a dip it can bridge depends on how much core there is above the gap, which is the least discussed benefit of going up one gauge.

On a 4.5mm board, even a small hollow under a plank will show as movement underfoot and will eventually work the click joint loose. The same hollow under a 5.5mm plank is likely to pass unnoticed. That does not remove the need to prepare the floor, and it should never be used as an excuse to skip levelling compound. It does mean that on a real site, where the substrate is never perfect, the thicker board gives the installer a margin that the thinner one does not.

The test itself takes minutes. Run a straight edge across the floor in several directions and look for the gaps underneath it. Anything that a rigid core cannot bridge needs filling first. Skipping this step is the single most common cause of a joint failing in the first year, and it fails regardless of how much you paid for the floor. The failure modes are described in more detail in the analysis of why SPC joints gap, pop or lift.

Six surface treatments are produced as standard, and the choice changes how the floor reads under light as much as the printed pattern does.

Deep embossed and EIR textures follow the printed grain rather than sitting on top of it, which is what makes a plank read as timber under raking light. Crystal and flat finishes take the reflection down and suit larger commercial areas where a strong grain across a big floor looks busy. Stone finishes cover the slate, concrete and travertine looks that get specified for bathrooms and entrance halls where timber would be out of place. Painted V-groove is a separate option applied along the plank edge, and it does create a line that catches dirt more readily than a flush edge, which is worth knowing before specifying it across a large floor.

 

Durability

The rigid core resists indentation from furniture legs and the point loads that damage a softer floor. A 5.5mm board with a 0.3mm wear layer handles day-to-day residential traffic without the surface pattern wearing through.

Waterproof

The core is non-porous and does not swell when water reaches it, which is what makes it workable in bathrooms, kitchens and basements. What the floor still needs is sealed perimeter joints, because a waterproof plank laid with an open gap at the wall is not a waterproof floor.

 

Installation without adhesive

The click profile engages by hand and the planks hold without glue, so the floor goes down over almost any flat substrate and comes up again the same way. No adhesive also means no curing time before the room can be used.

Acclimatise before laying

Leave the packs in the room for at least a day at the temperature the floor will live at. Rigid core moves less than laminate, but a cold plank laid into a warm room will still close up at the joints as it settles.

Leave the perimeter gap

The expansion gap applies at every wall, doorway and pipe, exactly as it does with any other floating floor. Packing the first row tight against the wall is the most common cause of a ridge appearing across the middle of a room a year later.

Cost over the life of the floor

A 5.5mm plank sits between hardwood and mid-range laminate on purchase price, and well below tile once installation labour is counted. Where it separates from the alternatives is maintenance: there is no sanding, no sealing, no recoating and no grout to clean, so the running cost is essentially zero beyond sweeping.

Material composition

The core is limestone powder and virgin PVC resin with no recycled filler, which is what keeps density consistent from batch to batch and keeps the click profile accurate. Vinyl can be recycled through dedicated collection streams at the end of its service life. Ask for the current batch documentation rather than relying on a general claim.

 

 

• SPC Flooring Thickness Guide: What Each Millimetre Buys You
• SPC Flooring Underlayment: When Do You Actually Need It?
• SPC Flooring Over Underfloor Heating: Thermal Resistance & Compatibility
• How Long Does SPC Flooring Last? Lifespan Factors Most Comparisons Skip
• SPC Flooring Click-Lock Quality: Why Joints Gap, Pop, or Lift
• Browse the Full SPC Flooring Range