The attached pad, and the column that says what it is made of
An attached pad is usually presented as a comfort feature. It is closer to a constraint: it decides what may go under the floor, and its material decides how it survives the thing most likely to attack it.
A pad bonded to the underside of the plank at the factory does three jobs. It softens the sound of the floor, it takes up a small amount of subfloor irregularity, and it sits between the plank and whatever moisture the subfloor gives off. Most tables record it as a yes.
The yes is the least useful part of the answer. A floor that arrives with a pad almost never permits a second underlayment beneath it, and adding one anyway is among the most common ways to void a warranty on a floor that was otherwise laid correctly. What the pad is made of decides how it behaves against an alkaline slab.
What the release shows
14 of the 16 products here arrive with a pad already bonded to the plank and two products do not. Of the 14 products that have one, five say what it is made of.
The materials that are named in this release are IXPE and cork, and they do not behave the same way. The difference matters most in the place a buyer is least likely to look: over a slab, where an alkaline surface and a cellulose-based pad are a worse combination than an alkaline surface and a closed-cell foam. A column that reads "yes" collapses that distinction into a comfort feature.
For the remaining 9 products the pad is declared and its material is not, so the absence is published here instead of an assumption. A pad whose material is unknown is also a pad whose behavior over a damp slab is unknown, and that is a different thing from a pad that is known to be fine.
Whether a pad is bonded to the plank, what the maker says it is made of, and how thick it is declared to be.
4 columns. The table scrolls sideways inside its own box; the row headings and the column headings stay in place while it does.
| Product | Attached pad | Pad material | Pad thickness |
|---|---|---|---|
| Bruce LifeSeal Classic | Yes | no declaration | 1 mm |
| Bruce LifeSeal Trending | Yes | no declaration | 1 mm |
| Ambient SPC Rigid Core 7x48 | Yes | held pending resolution | 1 mm |
| Cali Longboards 9x71 | Yes | IXPE | 2 mm |
| COREtec Pro Enhanced 7x48 | Yes | cork | no declaration |
| COREtec Pro Premium 9x72 | Yes | cork | no declaration |
| Karndean Korlok Select 5.87x23.46 | No | no declaration | no declaration |
| Karndean Korlok Select 8.86x55.91 | No | no declaration | no declaration |
| Mannington ADURA Rigid 6x48 | Yes | no declaration | 1 mm |
| Mannington ADURA Rigid 7x48 | Yes | no declaration | 1 mm |
| MSI Andover 7x48 | Yes | held pending resolution | 1 mm |
| MSI Cyrus 7x48 | Yes | held pending resolution | 1 mm |
| MSI Prescott 7x48 | Yes | held pending resolution | 1 mm |
| MSI XL Cyrus 9x60 | Yes | held pending resolution | 1 mm |
| Tarkett ProGen 12x24 | Yes | IXPE | 1 mm |
| Tarkett ProGen 7x60 | Yes | IXPE | 1 mm |
Why the material is the part that matters
Closed-cell foams are inert against the alkalinity a curing or damp slab produces. Cork is a plant material: it is quieter, it is warmer underfoot, and it is organic, which is a different relationship with a wet alkaline surface. Neither is the right answer in every room, and that is the point. A floor whose pad is named can be matched to the subfloor it is going over. A floor whose pad is a yes cannot.
The thickness column is worth reading beside it rather than instead of it. A thicker pad is not a better pad: past a certain depth it lets the plank move under load, which is the movement the joint has to absorb. The two columns answer different questions and neither answers the other, and a pad that is thick and unnamed has told a reader nothing twice.
What this note does not settle
This note does not rank the materials. Nobody here runs tests, and the behavior described above is the general property of the material rather than a measurement of any product here. Where a maker publishes an acoustic figure for its pad-and-plank assembly, that figure sits on the product page with the assembly it was measured on.
The table also does not say whether a second underlayment is permitted. That is declared per product in the installation instructions and read as its own field; where a maker permits one, the condition is published with it.