What Is Inside a Laminate or Rigid-Core Plank

Why this matters

Laminate and rigid-core vinyl plank look alike in a showroom, click together the same way and sell into the same rooms, and they fail in opposite ways. One swells when water gets into its joints and never shrinks back; the other shrugs off water and moves with the sun. Which of the two belongs in a laundry room, a sunroom or a basement is decided by the core, and so is how the crew cuts it, how it dents and how it behaves the first hot week. The joints themselves are covered in How to Install Laminate or Rigid Core Floating Floors; this card is about the layers around them.

The layer stacks

LAMINATE PLANK, TOP TO BOTTOM

 ==============================  overlay (wear layer):
                                 melamine resin with
                                 aluminum oxide
 ------------------------------  decor paper: printed
                                 wood or stone image
 ##############################
 ## HDF core: high-density   ##  click joints are
 ## fiberboard, wood fiber   ##  milled into it
 ## bonded with resin        ##
 ##############################
 ------------------------------  backer: balancing
                                 layer, keeps it flat

RIGID-CORE VINYL PLANK, TOP TO BOTTOM

 ==============================  wear layer: clear
                                 vinyl, usually with
                                 a urethane coat
 ------------------------------  print film
 ##############################
 ## core: SPC (stone-plastic ##  click joints are
 ## composite) or WPC (wood- ##  milled into it
 ## plastic composite)       ##
 ##############################
 ..............................  attached pad on some
                                 products: foam or cork

Laminate is a photograph of wood under a hard, clear resin, on a board of compressed wood fiber. The overlay carries aluminum oxide particles for scratch resistance, and abrasion performance is classified by AC rating under EN 13329, commonly quoted from AC1 for light residential up to AC5 for heavy commercial (check the edition the maker cites). The HDF core gives the plank its stiffness and its click profile. The backer balances the top layers so the plank does not bow.

Rigid-core vinyl plank is a printed film under a clear vinyl wear layer, on a core made mostly of PVC. The wear layer is sold by thickness in mils; the right one for a room is the maker's commercial or residential rating, not the number alone. The core comes in two families:

• SPC (stone-plastic composite): PVC heavily filled with mineral powder, commonly limestone. Dense, thin, hard and comparatively stable with temperature.
• WPC (wood-plastic composite): a foamed PVC core with additives. Thicker, lighter, softer and warmer underfoot, quieter, and it moves more with temperature and dents more readily than SPC.

What the core decides

Water

HDF is wood. Water that reaches the core through a joint or a cut edge swells the fiber, and the swelling does not reverse. The tell is a raised, slightly rounded edge along the joints near the dishwasher or the door to the yard. Some laminates are sold as water-resistant: their core is treated and their joints sealed, and the maker states the claim as a time that surface water can stand before it gets in. Read that number, and read the conditions on it; it covers a spill wiped up, not a leak under the floor.

PVC does not swell. The rigid-core plank itself survives standing water. The floor does not become waterproof because of that: water still runs through the joints and around the perimeter onto the subfloor, where it sits under a plank that will not let it dry. A rigid-core floor over a leak hides the leak while the subfloor stays wet underneath.

Heat

Vinyl moves with temperature. A rigid-core plank grows and shrinks with its own temperature far more than laminate does, and a dark plank in direct sun through a patio door runs much hotter than the room. SPC moves less than WPC. Makers address it with a maximum service temperature, a larger perimeter gap for sunny rooms, a shorter maximum run, or by excluding sunrooms and unconditioned spaces entirely. See related: Expansion Space at Walls and Fixed Objects.

HDF moves with humidity. Laminate responds to the house's seasonal RH, which is why its acclimation is about reaching in-service conditions with the HVAC running, not about a day count on the carton unless the maker gives one.

Dents and scratches

Laminate's aluminum oxide overlay resists scratching very well and its HDF core resists dents from point loads fairly well. SPC resists dents well. WPC dents more under narrow chair legs, appliance feet and rolling loads. Any of them can be dented by a refrigerator rolled across without a panel under it.

Cutting

• Laminate is cut with a saw. Aluminum oxide in the overlay dulls a steel blade within a few cuts, so crews use carbide or diamond blades. Sawing HDF makes fine wood-fiber and resin dust: cut outside or with a saw fitted with dust collection, and anyone exposed where the dust is not controlled wears a respirator under a written program per 29 CFR 1910.134 (applied to construction by 29 CFR 1926.103).
• SPC is usually scored with a utility knife and snapped along the line, which makes almost no dust and is why crews can cut it in the room. Notches and rips still need a saw or a jigsaw, with the same dust control.
• WPC scores and snaps too, though the softer core can crumble at the edge; follow the maker's method.
• Never cut vinyl hot. Do not use a heat gun to soften a plank for a cut or a bend unless its maker gives that method. Overheated PVC releases hydrogen chloride.

Reading the spec sheet against the layers

The carton's headline thickness is the number most easily misread. On a rigid-core plank with an attached pad, the total thickness includes the pad, so two products both sold as the same overall thickness can carry very different cores. Compare core thickness to core thickness, and wear layer to wear layer, and look for the maker's residential or commercial rating rather than ranking on one number.

The overall thickness still matters for one thing: height. It is what sets the transition to the next room, the clearance under a door, and the slide-in height for a dishwasher. Measure those before ordering, using the installed height the maker states, including any separate underlayment. See related: Transition Profiles and the Accessible Level Change.

Worked example: a laundry, a kitchen and a patio door

A 320 sq ft run through a kitchen, a laundry room and a breakfast area with a south-facing patio door, all on one level over a wood subfloor. The customer is choosing between a water-resistant laminate and an SPC plank, both in a similar oak look, both floating.

The laundry. The washer sits on the floor with a supply box and a standpipe behind it. A failed hose puts water under the floor, not on top of it. The laminate's water-resistance claim is for surface water that is wiped up within the maker's stated time; a hose failure overnight is outside it, and the swelling HDF would need the affected run replaced. The SPC plank would come through dry, but the subfloor under it would not. Either way the subfloor gets wet and the floor comes up to dry it. The core changes what is reusable afterward: SPC planks lifted off a dried subfloor can usually be relaid, while swollen laminate cannot.

The patio door. The plank near the glass sits in direct sun every afternoon. The SPC maker allows the product near glass with its standard gap and a limit on maximum run; the room's longest run is inside that limit. The laminate is unaffected by the heat itself. Neither product is excluded here, so the sun does not decide this job, but it would decide it against a WPC product whose maker excluded rooms with direct sun.

The kitchen. A dishwasher and a refrigerator. Both products are allowed, the floor goes in before the appliances are slid back, and both appliances are moved onto it across hardboard panels.

The call the crew writes up. SPC throughout, for one reason the customer can see: the laundry. The crew also writes down what SPC does not fix, in plain words on the quote: a leak under any floating floor still wets the subfloor, and a pan under the washer, a braided supply hose and a leak sensor are what protect the subfloor, not the plank. Cutting is score and snap inside, with the saw cuts for the door jambs and the dishwasher notch made on the driveway.

What would have flipped it. A customer who disliked the hard, cooler feel of SPC underfoot and had no washer on this level would get the laminate, and the only water risk left would be the dishwasher and the patio door, both of which a water-resistant laminate is rated for on the surface.

Things the core does not change

• Flatness. Both products are rigid planks spanning dips, and both peak or flex at the joints over a substrate outside the maker's tolerance. See related: Floor Flatness Tolerances by Floor Type.
• Fixed objects. Both float, and both are ruined the same way by an island set on top or trim nailed through.
• Underlayment rules. Both depend on the maker's underlayment list, and a product with an attached pad generally does not get a second cushion. See related: Underlayments and Vapor Retarders Under Floating Floors.

References

• EN 13329 (laminate floor coverings; abrasion classes)
• Flooring maker's installation instructions (water claims, temperature limits, maximum run, cutting method)
• 29 CFR 1910.134 (respiratory protection program)
• See related: How to Install Laminate or Rigid Core Floating Floors
• See related: Underlayments and Vapor Retarders Under Floating Floors