Preparing a Cement Subfloor for a Hardwood Flooring Installation

For most hardwood flooring installations, it’s recommended that you install your floors over a wood subfloor. That’s because the installation process is a little bit easier and you avoid the risk of additional moisture from installing over cement. Still, it’s not impossible with a cement subfloor, but it is only recommended to use an engineered hardwood on a concrete subfloor. The key to a proper installation is the initial preparation

Here’s three crucial factors you need to consider before installing hardwood on cement subflooring.

1. Check the Structural Integrity

The structural integrity of your subfloor is vital. Cracks, dips, soft spots, or other damages won’t just decrease the quality of your cement subflooring; they could also cause problems with  your hardwood floors over their lifetime.

Note: Older structures are particularly prone to having damaged cement subflooring, so take extra care when inspecting these subfloors before installation.

Look over your floors for any obvious damages. If everything seems uniform and in good condition, you most likely have nothing to worry about in terms of structural integrity. If you see major damages, you might need to call a contractor to do the repairs.

2. Is the Subfloor Level?

There is no way to use a level to test a cement subfloor, since no levels are long enough to span the entire width and length of the room. Instead, take a long wood plank and stretch it across your subfloor. Then, check for any dips or humps in the subflooring. They’ll be obvious to the naked eye.

If you notice a hump on the subfloor, sand it down using a concrete grinder. Don’t forget the protective mask and goggles!

If you notice any dips, you can repair them before installation with a floor patch. To use this, mix the compound together with water and carefully pour in a small amount. Then, even it out by moving the flat plank over the section repeatedly until it’s spread evenly around the floor, flattening the surface.

3. Check the Moisture Level

Cement retains moisture from the air and the ground. This porous material can pose a risk to the hardwood flooring if you install over cement at or below grade (or ground level).

When there’s an excess of moisture in the area or between the subfloor and flooring, the wood will soak it up like a sponge. When it does, there are two possible ways the floors will become damaged:

  • The planks will expand causing them to push against each other and eventually buckle
  • The wood will warp.

Measure your cement subfloors before you install. If they are below 4% on a moisture meter, you should not have a problem installing your wood floors over the cement subfloor.

Note: If the cement was laid within the past 60 days or less, let it settle before taking a reading. The moisture will move around, which could give you an inaccurate reading and risking your floor installation.

If you’re concerned about the moisture level in your home or region, use a moisture barrier when installing. This underlayment rolls out easily for your installation and will protect your floors from too much moisture seeping into your wood floors.

Don’t skip the preparation stage. Doing so will decrease the life of your floors and jeopardize the health of your investment.

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