Wood Floors Over Concrete in Miami: Test for Moisture First

Quick answer: Yes, you can put wood floors over a concrete slab in Miami, but use engineered wood and test the slab for moisture first. The two common tests are the calcium chloride test (ASTM F1869) and the in-slab relative humidity test (ASTM F2170). The flooring and adhesive makers set the passing numbers, and the installer should write the results down before any wood goes in.

Installing wood floors over concrete? Ask about our wood floor testing or call 908-232-6600, Monday to Friday, 9 to 5 Eastern.

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Read more: Laminate vs. Engineered Wood Flooring

Why Concrete Slabs Hold Moisture

Read more: What YOU Need to Know About Floor Buckling

Concrete is made with water and keeps giving off moisture long after it looks dry. A slab that sits on the ground can also pull moisture up from below. In Miami, the humid air adds to it. If wood goes down on a damp slab, the moisture moves into the wood, and the boards cup, buckle or lose their bond to the glue.

The Moisture Tests To Ask For

Read more: Understanding Wood Floor Checking

• Calcium chloride test (ASTM F1869): measures how much moisture comes up out of the slab's surface over a set time. A common limit for gluing wood is 3 pounds per 1,000 square feet in 24 hours, but follow the limit your flooring and adhesive makers give.

• In-slab relative humidity test (ASTM F2170): small probes go into holes drilled in the slab and read the humidity inside the concrete. Many makers now prefer this test.

• Moisture meter readings: a quick check that's useful for finding wet spots, but it doesn't replace the tests above.

Ask for the readings in writing. Many flooring warranties require them.

Is The Slab Flat Enough?

Shown: Helsingborg Wide Plank

Wood needs a flat base. Flooring makers set their own limit, often around 3/16 of an inch over 10 feet or 1/8 of an inch over 6 feet. High spots get ground down and low spots get filled with a patch or self-leveling compound before installation.

How Wood Goes Over Concrete

Shown: Bergen Wide Plank

• Glue-down engineered wood: the most common method in Miami. It uses an adhesive made for wood flooring, often one with built-in moisture control.

• Floating engineered wood: boards lock or glue to each other and sit on an underlayment with a moisture barrier. Condos often need a sound underlayment too. See Wood Floors in Brickell Condos.

• Plywood over the slab, then solid wood: possible, but it adds height and more moisture control steps.

For more on barriers, read Moisture Barriers: Protecting Your Investment.

Let The Wood Settle In

Read more: How We Deliver

Bring the flooring into the home with the air conditioning running at normal settings, and follow the maker's instructions on how long it should sit before installation. The installer should check the wood's moisture as well as the slab's. Read Why Flooring Installers Need to Measure Moisture Content.

Frequently Asked Questions

Can You Install Hardwood Directly On Concrete In Florida?

Engineered wood can be glued directly to concrete once the slab passes a moisture test and is flat. Solid wood normally needs a plywood subfloor first.

How Long Does A New Concrete Slab Need To Dry Before Wood Floors?

It depends on the slab's thickness, the mix, and the air in the building, so there's no single answer. Test it rather than counting days.

What Happens If Wood Is Installed On A Wet Slab?

The wood takes on moisture from below, which can cause cupping, buckling or the glue letting go. Fixing it usually means removing the floor.

Do I Need A Moisture Barrier Under Wood Floors On Concrete?

Usually yes, either as a separate membrane or built into the adhesive or underlayment. Follow the flooring maker's instructions.

Talk To A Wood Floor Expert About Your Brickell Home

Brickell Wood Floors, a Huggins Wood Floor Specialist brand, is led by Joe Avila, who brings 26 years in wood flooring and NWFA certifications (CSI, CI, CWFI, CFS). For more than a decade Joe has taught accredited continuing-education programs to AIA, ASID and IDCEC audiences. He trained at NWFA schools in advanced European techniques, including bending wood, custom herringbone and parquet design, mixing species, fuming, aniline dyes, tannic reactions and smoking. We serve Brickell and South Florida's luxury residences and ship material nationwide.

Call (908) 232-6600 (9am to 5pm Eastern), email Joe@hugginsflooring.com, book a virtual consultation, or send us a message.

Need your slab or floor tested before installing? See our wood floor testing and inspections and consultations, or call 908-232-6600.