You typically put an underlayment (or suitable subfloor layer) between the structural subfloor and vinyl flooring, but the exact material depends on your subfloor type, vinyl variety, and room conditions.

Do you need something under vinyl?

In many cases yes, but not always.

  • Many modern luxury vinyl tiles or planks (LVT/LVP) come with built‑in foam or cork backing , so installing extra underlayment on top of that can actually cause problems.
  • If your vinyl is thin or low‑quality , or if the subfloor is uneven, noisy, or over concrete, adding an extra underlayment layer is usually recommended.

Common underlayment materials

These are the layers you might use under vinyl when needed:

  • Foam underlayment
    • Provides cushioning, sound reduction, and adds a bit of thermal insulation.
* Best over **plywood or OSB** ; avoid foam‑only under concrete unless it has a vapor barrier, because foam can trap moisture.
  • Felt underlayment
    • Often used with vinyl in homes for noise reduction and a smoother surface.
* Works well over wood subfloors but typically needs a separate moisture barrier if you’re over concrete.
  • Cork underlayment
    • Eco‑friendly, offers good insulation and some sound‑dampening.
* Good choice if you want a firmer, more stable feel under click‑lock vinyl.
  • Rubber or high‑density pads
    • Better for high‑traffic areas; they’re durable and help reduce impact noise.
* Often used in commercial or multi‑use spaces rather than basic residential installs.
  • Plywood or particleboard (for sheet vinyl or repairs)
    • With sheet vinyl , installers often level things with 6 mm plywood or similar boards over joisted subfloors.
* Particleboard is cheaper but less moisture‑resistant and more fragile, so it needs a very solid base and good preparation.

Concrete vs. wood subfloor

  • Over concrete slabs
    • Use a foam or cork underlayment with integrated vapor barrier , or a separate poly sheet, to prevent moisture from rising.
* If the slab is uneven, you may first apply a **self‑leveling compound** , then add underlayment.
  • Over wood subfloors (plywood, OSB, floorboards)
    • A thin foam or felt underlayment is usually enough to smooth minor imperfections and quiet footfall.
* If the floorboards are rough or squeaky, you can add a **plywood or particleboard layer** first, then underlayment and vinyl.

Quick rule‑of‑thumb table

Situation| What to put under vinyl
---|---
Vinyl with built‑in foam backing on clean wood| Usually nothing extra ; just prepare the subfloor. 58
Loose‑lay or glue‑down vinyl| Follow manufacturer instructions ; often no extra underlayment. 810
Vinyl over concrete slab| Foam or cork underlayment with vapor barrier (or poly sheet). 37
Click‑lock vinyl with uneven or noisy floor| Thin foam or cork underlayment over a level, firm base. 13
Sheet vinyl over joisted subfloor| 6 mm plywood layer first, then the vinyl. 9

One thing to watch

Using too soft or thick an underlayment (like plush foam) under a floating click‑lock vinyl can lead to tab damage and gapping , because the planks never fully lock down. Always check the vinyl manufacturer’s specs —those override generic advice.

If you tell the exact type of vinyl (e.g., “luxury click‑lock plank on concrete” or “sheet vinyl on plywood”), I can give you a very specific “here’s exactly what to lay, in what order.”