Best Flooring for a Concrete Slab: Matched to Your Slab’s Moisture

For most slab homes, the best flooring for a concrete slab is rigid-core SPC vinyl plank, and the reason is a number.

The floors we stock disagree by almost three to one on how damp a slab may be: PermShield allows up to 8 lb of moisture vapor per 1,000 sq ft under its SPC vinyl, while Chesapeake caps its laminate and engineered hardwood at 3 lb.

SPC tolerates the most moisture, floats over a 6-mil poly sheet and shrugs off spills from above.

Laminate and engineered wood work too, when the slab tests dry enough for them and you follow their extra rules.

Short answer: pick the floor your slab’s moisture numbers allow

Ask for a moisture test before you fall in love with a sample. The manufacturers name two standard tests: ASTM F1869 measures how much moisture vapor the slab gives off, using anhydrous calcium chloride, in pounds per 1,000 sq ft; ASTM F2170 reads the relative humidity inside the slab with probes set into it.

Ask your installer which one they run and get the result in writing, then read it against these ranges from each manufacturer’s instructions:

• Up to 3 lb (F1869) or 75% relative humidity (F2170): all three types are in range. Laminate still needs 6-mil poly if a concrete meter reads above 4.0; floating engineered wood goes over 6-mil poly plus closed-cell foam.
• Between 3 and 8 lb, or 75% to 90% RH: SPC vinyl over 6-mil poly is the one that stays inside its limits. Chesapeake allows engineered wood between 3 and 7 lb only over an impermeable vapor retarder rated 1 perm or less.
• Above 8 lb or 90% RH: none of the floors we sell should go down until the moisture source is dealt with.
• Below grade (a basement or sunken room): SPC and our Chesapeake laminate are approved; for real wood, only the lines rated below grade.

Every SPC line on our waterproof flooring in North Charleston page is rigid-core and arrives with a foam pad already attached.

SPC vinyl, laminate and engineered wood over concrete, side by side

Two notes on the table. First, “waterproof” on an SPC box describes spills from above; the manufacturer’s warranty still excludes moisture coming up from the slab, which is why the poly sheet is required.

Second, a slab that passes today can change with the seasons. Chesapeake says outright that a test does not guarantee a dry slab year-round, and expects a 6-mil poly layer between the ground and the concrete itself.

Tile set in mortar, polished or coated concrete, and carpet also go over slabs. We don’t sell them, so we haven’t read their makers’ moisture limits.

One point of comparison does exist: in flood-prone areas, FEMA’s Technical Bulletin 2 rates mortar-set ceramic or porcelain tile and poured epoxy floors as flood damage-resistant, and carpet, laminate and wood floors as not.

If you are comparing looks rather than limits, our laminate flooring selection and engineered hardwood in North Charleston and Richmond pages show every color in each line.

What our own product pages say about installing on grade

We went through the installation fields on our product pages, line by line.

Of the engineered lines that state an installation level, three are rated for below-grade use: Chesapeake Points East and Veranda’s Asheville and Charleston collections. Two, Chesapeake Cromwell and Chemistry, are rated on or above grade only, which still includes a slab poured on the ground but not a basement.

The nine Denali collections we list are glue-down or glue-assisted nail-down products, so on a slab they go into adhesive rather than floating. For SPC and laminate the levels come from the manufacturers’ manuals: PermShield allows on, above and below grade, and Chesapeake says its laminate may be installed on all grade levels.

Several collections don’t state a level on our pages yet (Aged Wide Floors, Hallmark, Symphony and Sienna, among others). If one of those is the look you want, ask us for the manufacturer’s installation sheet before you plan around a slab.

Why the same slab can pass for one floor and fail for another

Each manufacturer sets its own ceiling because each product reacts differently to moisture coming up through concrete, and each warranty excludes damage from that moisture.

Chesapeake’s laminate guidelines state that it does not warrant installations that fail because of excessive alkali, moisture or hydrostatic pressure in the subfloor. PermShield warns that subfloor moisture trapped under a floating floor can lead to mold and mildew.

So the test result decides more than the sample board does. Two habits protect you:

• Get the numbers in writing. Chesapeake asks installers to document subfloor moisture readings; PermShield asks for the test locations and results to be recorded. For engineered wood, Chesapeake recommends at least three test spots for areas up to 1,000 sq ft, plus one more for each additional 1,000 sq ft.
• Don’t skip the plastic. On or below grade, the 6-mil polyethylene sheet is part of the SPC install, not an upgrade. We explain why a padded plank still needs it in our guide to underlayment for vinyl plank flooring.

Flat, cured and not too cold: the rest of the slab checklist

Moisture is the first gate, not the only one. All three manufacturers ask for a slab that is flat within 3/16 inch over 10 feet: grind the high spots and fill low spots with a Portland cement-based leveling compound.

Chesapeake also wants concrete at least 90 days old and fully cured, and for engineered wood a slab of at least 2,500 PSI.

Comfort is the detail people notice after move-in. PermShield’s manual points out that a concrete floor can run up to 10 °F colder than the air in the room, which makes the attached pad on SPC planks worth having on a slab.

Keep the room between 65 and 85 °F during and after installation for SPC and laminate; for engineered wood, Chesapeake asks for 60 to 80 °F and 35% to 55% relative humidity, with the HVAC running for 14 days before the floor goes in.

Real wood over concrete: what the labels allow

If you want real wood on a slab, the answer is engineered, not solid. Our engineered flooring page explains why: solid boards are best above grade and are not ideal for basements, while engineered planks, with a wood veneer over a layered core, can go over concrete and below grade.

Two installation routes exist.

• Floating, with the planks glued to each other at the tongue and groove over 6-mil poly and closed-cell foam (Chesapeake also accepts a two-in-one foam and moisture barrier made for wood floors).
• Glue-down, with a urethane or cross-link wood-flooring adhesive.

Either way, the flooring acclimates for at least 72 hours on site, and cartons stored on an on-grade slab sit four inches off the concrete.

If your slab is in Summerville, where half the homes were built in 2000 or later (Census estimates for 2020 to 2024), our page on flooring for Summerville, SC homes covers both kinds of house there: newer homes on slabs and the raised cottages of the historic district, which sit over a crawl space.

What decides the price of a floor over concrete

A quote for a floor over concrete is built from these pieces, and each one can move it up or down:

• The product line and its thickness, wear layer and installation method (floating or glue-down).
• Slab prep: grinding, leveling compound and patching to reach 3/16 inch over 10 feet.
• Moisture results: a 6-mil poly sheet is routine; a slab near the upper limits may need a vapor retarder rated 1 perm or less, or work on the moisture source first.
• Adhesive, foam and poly, plus transitions and moldings at doorways and stairs.
• Square footage plus waste: Chesapeake suggests 10% extra for laminate and 5% for engineered; PermShield 5%, and more in rooms with many angles.

Still deciding between looks and rooms? Start with our guide on how to choose flooring. Ready to match a floor to your slab? Bring your moisture readings, or ask us how to get them, and see the waterproof flooring options for slab homes at our North Charleston or Richmond showroom.

Sources: PermShield installation instructions (rev. 09/01/2023); PermShield warranty (rev. 09/01/2023); Chesapeake laminate installation guidelines (rev. 6/1/2025); Chesapeake engineered hardwood installation guidelines (rev. 6/1/2025); FEMA Technical Bulletin 2 (January 22, 2025); installation fields on TRD Floor Supplies product pages.