Wear layers, AC ratings, PEI and Janka — what each one does and doesn’t tell you

Every flooring category invented its own durability scale, none of them measure the same thing, and all of them get called “how tough this floor is” in the marketing copy. A 20 mil wear layer, an AC4 rating, PEI 4 and a Janka of 1360 are four answers to four different questions. Here is what each predicts — and, the part nobody prints on the box, what it says nothing about.

Vinyl wear layer: mil versus mm

The wear layer is the clear film over the printed design — the only thing between your boots and the pattern. It is measured in mils: one thousandth of an inch, or 0.0254 mm. That conversion causes more confusion than any other spec in flooring.

If a vinyl product quotes a wear layer in millimetres and the figure is 2 or 5 or 8, that is not a wear layer — it is plank thickness in the wrong row. A genuine 2 mm wear layer would be roughly 79 mil.

What a wear layer does not tell you:

• Nothing about the coating on top of it. Most planks carry a UV-cured urethane, and that is what resists day-to-day scuffing. Two planks with identical wear layers can scuff completely differently.
• Nothing about dents. Indentation is core density — a rigid SPC core resists a chair leg where a soft plank with a thick wear layer holds the mark.
• Nothing about the locking joint, which fails first on most floating floors, or about the seams. Water does not go through a wear layer. It goes around the plank.

Laminate: AC1 to AC5

The AC rating comes from EN 13329, and it is a class rather than a score. A board passes a battery of tests — Taber abrasion, impact, staining, castor-chair cycling, thickness swell — and is awarded the lowest class it passes across all of them, which makes it hard to win on one strong result.

What an AC rating does not tell you:

• Anything useful about water. The standard includes a controlled edge-swell test; it is not a waterproof rating, and an AC5 laminate still swells at a joint left wet. Water resistance is a separate claim, and it belongs to the core and the joint.
• Anything about the locking system, which is where a laminate floor loosens, gaps and starts to click.
• Anything about sound, which is density, underlay and a flat subfloor — or about how convincing the floor looks, which is embossing and a good bevel.

Tile: PEI, and the numbers that matter more here

PEI is a glaze abrasion class from 0 to 5, answering one question: how much foot traffic crosses this glaze before it visibly dulls? PEI 0 is walls only; 1 is bare feet in an ensuite; 2 is light residential; 3 covers all normal residential floors including kitchens; 4 is heavy residential and light commercial, which is what an entry deserves; 5 is heavy commercial.

What PEI does not tell you — and in Canada this is the important part:

• Nothing about frost. That is water absorption. Porcelain is defined by an absorption of 0.5% or less, and it is that figure, not PEI, that decides whether a tile survives an unheated entry or a covered porch through freeze-thaw.
• Nothing about slip. That is coefficient of friction. For a wet mudroom you want the wet DCOF, where 0.42 under ANSI A137.1 is the usual benchmark. A PEI 5 tile can still be lethal in February.
• Nothing about breaking strength. A tile cracks because the substrate beneath it deflected, not because it was walked on too often.
• Nothing at all, if the tile is unglazed. Through-body porcelain has no glaze to abrade, so it often carries no PEI number — the rating does not apply.

Hardwood: Janka, and the number that matters more

Janka measures the force in pounds needed to embed an 11.28 mm steel ball halfway into a sample of the species. It is a dent test, and only a dent test. Red oak at 1290 is the reference everything else is judged against.

What Janka does not tell you:

• Nothing about the finish — and on a prefinished floor the finish is the only thing your shoes touch. A tough aluminium-oxide coating on a soft species outlasts a bare hard one.
• Nothing about scratching. Janka measures indentation; a dog’s claws scratch a coating, they do not dent the wood.
• Nothing about stability, which in a Canadian winter decides whether you get gaps. Hickory is among the hardest common species and the most seasonally active.
• Nothing about how visible damage will be. Rustic grade, wire-brushing and a low sheen hide wear that a smooth glossy floor broadcasts.

On engineered hardwood there is a more useful number than Janka: the veneer thickness, the depth of real wood above the core. That, not the species, decides whether the floor can ever be sanded — the difference between one life and three.

Where these figures appear on our site

Those are the four systems you will meet. The counts below are flooring products we list in each category with a price attached; trims, adhesives, underlays and tools are excluded.

Read that as a count of listings, not a count of listings that publish a rating. We do not have a wear layer for every vinyl plank, an AC class for every laminate, a PEI number for every tile or a Janka figure for every hardwood — the product data is what each supplier sends. Where a manufacturer publishes the figure, it appears in that product’s spec table; where it does not, the spec table does not invent one. Ask us, and we will go to the technical sheet.

Why thickness keeps getting mistaken for durability

Of everything we list, 37,972 products carry a thickness figure, and 13,301 of those sit in the single 3–4 mm band. Thickness is the number shoppers reach for first and the one that decides least about wear: it is a structural spec — rigidity, how much subfloor unevenness a plank bridges, how the floor sounds, how much height you add at the doorway. Narrow the shortlist with thickness; choose inside it with the wear rating.

Matching a rating to a room

Buying the top rating everywhere wastes money; buying the bottom one at the front door shows within two winters.

1. Entry and mudroom. Grit, salt and meltwater. Buy the top of whatever range you are shopping — 20 mil vinyl, AC4 laminate, PEI 4 tile with a wet DCOF you have checked.
2. Kitchen and main hallway. Traffic, dropped pans, chair castors. One step below the entry is usually right.
3. Living and dining rooms. Wear concentrates in lanes, not evenly. Mid-range ratings, and put the design budget here.
4. Bedrooms and the home office. The lightest-used floors in the house; a modest rating is genuinely enough. A rolling chair on a mat is the only real threat.
5. Basements. Rating is secondary — what the slab is doing decides this room.

The short version

• A mil is 0.0254 mm. A vinyl wear layer quoted in whole millimetres is probably the plank thickness.
• An AC class is the lowest result across a battery of tests — hard to game, and silent about water.
• PEI is glaze abrasion only. In Canada, water absorption and wet DCOF matter more.
• Janka is a dent test on a species, not a scratch test on your floor — and on engineered wood, veneer thickness decides whether it gets a second life.

Shop what this guide covers

• vinyl planks (LVP and SPC) — where a wear layer in mils is the number to read.
• laminate planks — where the AC class is.
• floor tiles — where PEI, water absorption and wet DCOF are.
• hardwood flooring — where the species and, on engineered, the veneer decide it.
• How thick should your floor actually be? — the spec this article keeps telling you not to shop on.