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Prepping Concrete Slabs for Hardwood Flooring Set up


Staff member
Mar 15, 2024
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Installing a wood floor over concrete
Installing a wood floor over concrete

To many hardwood flooring contractors, putting in hardwood flooring over concrete could be a little bit of a puzzle. The next is a information to assist alleviate any considerations or worries about putting in hardwood flooring over concrete.

The key behind a profitable set up over concrete is to deal with 5 key areas: Situation of slab, kind of concrete, location of slab, flatness, and moisture.

Learn on for in-depth particulars on these 5 key areas:

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One of many best and most helpful steps to take is to rigorously study the situation of the concrete slab. Check out the slab and observe any cracks, spalling, or curling at growth joints.

That is additionally the time to notice any excessive or low spots within the concrete. Presently the Nationwide Wooden Flooring Affiliation (NWFA) recommends 1/8″ to three/16″ in a 10FT radius. You’ll have to grind down the ground or use a self-leveling compound to even out the slab. Shop our selection of subfloor leveling products.

Should you take the time to look at the concrete and set about to repair any potential issues, you’ll save your self time and power in a while. In any case, if concrete slab is in poor situation, your hardwood flooring usually tend to fail.


Checking the moisture score of a concrete slab is arguably an important check to carry out when assessing a concrete slab. Moisture is claimed to trigger upwards of 90% of hardwood flooring failures.

Watch our video on using the Wagner Rapid RH 4.0 to measure the RH of a concrete slab.Watch our video on using the Wagner Rapid RH 4.0 to measure the RH of a concrete slab.

Relating to moisture and concrete slabs the 2 most acknowledged exams are calcium chloride and relative humidity. Click on right here to study extra about these two exams, and the way they examine.

Understanding the moisture content material of a concrete slab and taking the mandatory steps to fight moisture will assist immensely in efficiently putting in hardwood flooring over concrete.


We all know that there are a lot of various kinds of hardwood that carry out in a different way. We take note of the kind of wooden and work with it in a approach to get the very best set up. The identical is true with concrete.

There can be data (supplied by architects, builders, and engineers) that offers particular details about the concrete slab in query. This data will embrace figures like PSI, CSP (Concrete Floor Profile), and Flatness (FL, FF, & F-min). Typically you’ll discover the concrete is definitely a light-weight concrete. In that specific state of affairs, you’ll must take extra steps earlier than putting in the hardwood flooring. Should you didn’t know a concrete slab was light-weight concrete, you may need incorrectly put in the hardwood ground.

Gathering the data on the concrete will help you throughout the set up. You’ll be on the trail to appropriately set up the hardwood ground on the required concrete.


Above grade vs. below grade for concrete slab
Above grade vs. below grade for concrete slab

Picture credit score www.hardwoodinfo.com

This step is perhaps the simplest to find out. Nevertheless, there are nonetheless issues you might want to be aware of. When figuring out the situation of the slab what you’re in search of is whether or not the slab is at, above, or beneath grade.

Irrespective of the place the concrete slab is situated, you need to know find out how to take care of it. Slabs above grade have much less moisture than below-grade slabs. Nevertheless, slabs above grade may additionally have a weight restrict. For instance in a condominium you won’t have the ability to put down leveling compound due to the burden it will add to the concrete slab. In a beneath grade set up, there may be extra moisture and often meaning including moisture/vapor obstacles.


In most eventualities when a concrete slab is poured, the concrete is poured and screeded right into a pre-made type. The professionals pouring the concrete will certainly make the slab appear stage and flat, however that doesn’t essentially imply the concrete is flat sufficient to put in hardwood flooring.

Utilizing one in all many various instruments — a straight edge, mason’s string, or a laser — can decide the true flatness of a concrete slab. Sometimes a ground is flat when it’s 3/16″ over a ten′ radius or 1/8″ over a 6′ radius.

If the concrete slab shouldn’t be stage then you definitely both want to make use of leveling compound to fill in low spots or grind away excessive spots.

Or, if the state of affairs requires it, putting in a subfloor over the concrete slab is perhaps the best choice.

In any state of affairs, ensuring the concrete is flat and stage sufficient to put in hardwood flooring over is paramount.

Hardwood flooring are put in over concrete by wooden flooring mechanics on a regular basis. When you find yourself educated about how concrete works and the way it interacts with hardwood flooring, you’ll be ready to put in a stupendous ground over concrete.

Should you’d wish to study extra about making ready a concrete slab for hardwood flooring, name us at (800) 787-1786 or e-mail [email protected]
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