Do You Need Underlayment for Vinyl Flooring?

Short Answer

Sometimes. Many rigid‑core vinyl planks already have an attached pad and don’t need another layer. Add separate underlayment only when your product manual says it’s allowed and when you need sound control, moisture protection over concrete, or a slight comfort boost.

When You Need Underlayment

Concrete subfloors: vapor barrier underlayments are often required below grade or where slab moisture is present.
Sound control goals (multi‑level homes, condos, apartments).
Comfort and minor gap bridging when the brand allows it.

When You Don’t

Your vinyl has an attached pad designed for floating installs.
The manual says “no additional underlayment.” Extra cushion can stress click‑lock joints and void warranties.

Vinyl plank with pre-attached underlayment pad — Follow manufacturer guidance to protect your warranty

Underlayment Types (Quick Guide)

Basic foam (IXPE/EVA): light cushion and sound; common as an attached pad. Only add separately if your brand permits.
Sound‑rated pads: designed to improve STC/IIC for multi‑family and upstairs spaces; ensure vinyl compatibility.
Vapor barrier underlayments: add moisture protection over concrete.
Combo pads (sound + vapor): convenient all‑in‑one solutions when approved by the manufacturer.

STC/IIC Basics (Noise Ratings)

STC measures airborne noise (voices, TV). IIC measures impact noise (footsteps). Higher numbers = better.
Check building/HOA minimums and choose an approved pad to meet them.

Concrete vs. Wood Subfloors

Over Concrete

Manage moisture with approved vapor barriers where required.
Fix high/low spots; flatness matters more than softness.
Keep slabs clean and dry before you float click‑lock vinyl.

Over Wood

Fasten loose subfloor panels to eliminate squeaks.
Address deflection and ensure overall flatness.
Use only pads your vinyl brand approves to avoid stressing the locks.

Attached Pad vs. Separate Pad

Attached pad simplifies installs and is tuned for the floor’s locking system.
Separate pads can add sound control or moisture protection, but only if the brand says they’re compatible.

Installation Tips

Read the manual first. Use only the underlayments listed as approved substrates.
Don’t double‑pad. Too much cushion causes flexing, joint gaps, and lock damage.
Tape seams of vapor barriers per instructions; keep them wrinkle‑free.
Maintain expansion gaps at walls and fixed objects.

Common Mistakes

Adding a soft pad under vinyl with an attached pad.
Using carpet padding—never approved for vinyl plank.
Ignoring moisture on concrete slabs.
Skipping flatness fixes and hoping a pad will hide it.

Tools & Materials

Approved underlayment (as specified by your brand)
Vapor barrier and tape (for concrete, if required)
Straightedge/level, patching compound, sander/grinder
Utility knife, shears for trimming pads

FAQs

Do I need an underlayment if my vinyl has an attached pad?

Usually no. Most brands prohibit extra pads over attached‑pad products.

What about installing over tile?

You may need a specific pad or none at all—start by fixing flatness. See vinyl over tile.

Will underlayment make my floor last longer?

Not directly. Longevity depends more on wear layer and care. For lifespan guidance, see vinyl lifespan.

What underlayment thickness is best?

Thicker isn’t always better. Use only thicknesses your vinyl brand approves so the locks aren’t overstressed.

What’s a good wear layer for busy homes?

See wear layer thickness.

New to vinyl plank?

Start here: what is vinyl plank flooring.

Bottom Line

Use underlayment only when your vinyl brand allows it and when you need sound control or moisture protection. Over concrete, manage vapor first; over wood, fix squeaks and flatness. Avoid extra cushion under attached‑pad floors, and your vinyl will perform quietly and reliably.