What Underlayment Goes Under Laminate, Vinyl, and Tile?

TL;DR: Laminate flooring needs a foam or felt underlayment (usually $0.30-$0.60 per square foot) for cushioning and sound dampening. Most rigid-core luxury vinyl plank already has an attached pad and needs no extra layer, while sheet vinyl over a rough subfloor may need a thin plywood underlayment. Tile never goes over foam; it needs cement backer board, an uncoupling membrane like Schluter DITRA, or a mortar bed, plus a moisture barrier if you're over a concrete slab.

_Last reviewed: July 2026 · 6 min read_

You bought the flooring, checked the price, and now the installer or the box at the store is asking about underlayment, and it's a different answer for every material. Get it wrong and you'll hear hollow footsteps through laminate, feel a soft spot under vinyl, or watch tile crack within a year. Here's what actually goes under each type, and why substituting one for another causes problems.

Okoniq Property Hub logs which underlayment and flooring products went into each unit, so you're not guessing what's under the floor next time it needs a repair or a tenant asks.

What underlayment goes under laminate flooring?

Laminate needs a foam or felt underlayment between the planks and the subfloor, almost without exception. This layer does three jobs: it cushions the click-lock joints so they don't crack under foot traffic, it dampens sound between floors, and it smooths out minor subfloor imperfections up to about 1/8 inch.

Standard 2mm-3mm foam underlayment runs $0.30 to $0.60 per square foot and works fine over a dry wood subfloor. If you're installing over concrete, particularly a basement slab, you need a combination underlayment with an attached vapor barrier, or a separate 6-mil polyethylene sheet under the foam. Concrete wicks moisture even when it looks bone-dry, and laminate's fiberboard core swells and delaminates if it sits on damp concrete for months. If you've had any signs of dampness from below, it's worth ruling out a slab leak under your floor before you install anything.

Some laminate lines, like certain Pergo and Mohawk products, sell "attached pad" planks that already include the foam layer. Adding a second layer of underlayment under these voids the manufacturer warranty in most cases, so check the installation manual before you double up.

What underlayment goes under vinyl plank or sheet vinyl?

Most rigid-core luxury vinyl plank (LVP) and stone-composite vinyl (SPC) already has an attached foam or cork pad on the back, so no separate underlayment is needed or recommended. Adding foam under click-lock rigid vinyl can actually cause the locking joints to flex and separate over time, which is the opposite of what you want.

Flexible vinyl plank without an attached pad, and older-style peel-and-stick vinyl tile, are different. These need a smooth, flat surface, so a 1/4-inch plywood or luan underlayment is standard over uneven subfloors, screwed down every 6 inches to kill squeaks. Sheet vinyl in kitchens and bathrooms follows the same rule: smooth plywood underlayment, never foam, because foam creates soft spots that tear under appliance weight or foot traffic.

Moisture matters here too. If you're covering a slab that stays humid, check crawlspace or basement conditions first. A basement dehumidifier running before and during installation keeps humidity below the 55-60% range that causes vinyl adhesive to fail early.

What underlayment goes under tile?

Tile needs a rigid, stable substrate, never foam or standard laminate underlayment. The three common options are cement backer board (like HardieBacker or Durock, roughly $12-$18 per 3-by-5-foot sheet), an uncoupling membrane like Schluter DITRA ($1.50-$2.50 per square foot), or a traditional mortar bed for older-style installations.

Backer board is screwed to a plywood subfloor and taped at the seams, then tile is set directly on top with thinset mortar. DITRA and similar membranes are thinner, add less height, and isolate the tile from minor subfloor movement, which matters over wood-framed floors that flex slightly with seasonal humidity changes. Over a concrete slab, either option works, but a moisture barrier underneath is required if the slab is below grade or has ever shown signs of dampness.

| Option | Best for | Cost/sq ft | Adds height | |---|---|---|---| | Cement backer board | Plywood subfloors, wet areas | $1.00-$1.50 | 1/4"-1/2" | | Uncoupling membrane (DITRA) | Wood-framed floors, radiant heat | $1.50-$2.50 | 1/8" | | Mortar bed | Older homes, uneven slabs | $2.00-$3.00 | 1"-1.5" |

Skipping a rigid substrate is the single biggest cause of cracked grout and loose tile within the first two years. Tile has zero flex tolerance, unlike laminate or vinyl.

Do you need a moisture barrier under any of these floors?

Yes, if you're installing over concrete, a crawlspace, or any slab-on-grade, in which case a moisture barrier belongs under laminate, most vinyl, and tile alike. Concrete moisture vapor emission is invisible to the eye but measurable, and it's the reason manufacturers require testing before warranty coverage applies.

A simple calcium chloride test or a plastic sheet taped down for 24 hours (checking for condensation underneath) will tell you if you have a moisture problem before you spend money on flooring. If the slab tests wet, address the source first. Persistent basement moisture often traces back to grading, gutters, or a foundation crack, and basement waterproofing fixes the cause rather than papering over it with an extra plastic sheet.

For laminate and vinyl, a 6-mil polyethylene barrier under the underlayment is standard. For tile over a slab, a liquid-applied or sheet membrane rated for below-grade use does the same job without adding much height.

FAQ

Can I put laminate underlayment under vinyl plank?

No, standard foam laminate underlayment is too soft for rigid-core vinyl plank and causes the click-lock joints to separate under weight. Use only the attached pad the product came with, or no additional layer at all.

How thick should underlayment be for laminate flooring?

Most laminate underlayment runs 2mm to 3mm thick, which is enough to smooth minor subfloor dips and reduce sound without raising the floor height enough to cause problems at doorways.

Do I need cement board under tile if I'm using a membrane like DITRA?

No, DITRA and similar uncoupling membranes replace cement board in most residential installations and go directly over a plywood subfloor, saving about 1/4 inch of height.

What happens if you skip underlayment under laminate?

Skipping underlayment under laminate causes a hollow, hard-sounding floor, faster wear on the click-lock joints, and often voids the manufacturer's warranty since most laminate products require an underlayment layer.

How do I know if my concrete slab is too damp for flooring?

Tape a 2-foot square of plastic sheeting to the slab, seal the edges, and check after 24 hours; condensation or a darkened patch underneath means the slab is too damp to install flooring without a vapor barrier and possibly a drying period first.

This is educational information, not construction or engineering advice. Check your specific flooring manufacturer's installation guide and consult a licensed flooring contractor for moisture testing or subfloor issues you're unsure about.