The proper steps need to be taken in preparing a home’s concrete slab and wooden subfloor in order for a high quality and successful flooring installation to occur. In this article we will take a look into the necessary preparation steps and explain why they are important. Homeowners, be sure that your floors are receiving this detailed approach when working with pros, and for installers, be sure to implement these steps into your installation protocol.

Concrete Slab
All adhesive manufacturers, flooring manufactures as well as the NWFA require a floor’s concrete slab to be properly prepped, swept and free of all debris. When dealing with a concrete slab this is critical because any left-over adhesive, sheet-rock, mud or any other agent left behind will affect the bond between adhesive and flooring, whether engineered or hardwood. Any humps that aren’t ground down and low spots that aren’t filled can make the flooring not lay flat. It will look uneven because the flooring will naturally follow the couture of the slab underneath it. A wise man once said “A home is only as strong as its foundation,” and your concrete slab is the foundation of your floors. You might respond with,  “but my slab is brand new.” However, that doesn’t mean the slab doesn’t need to be scraped and prepped. Often there is a sealer on the top of the slab that will need to be scraped off with razors to open the pores of the slab for a proper bond during installation.

Wooden Sub-floors
In addition to concrete slab requirements, all flooring manufactures as well as the NWFA require a wooden sub-floor to be swept, prepped and free of all debris. This is critical for the similar reasons to that of the concrete slab. When felt paper or underlayment is installed without proper floor prep, or the plywood sub floor is not flat, the resulting discrepancies can cause wood to stand up in certain areas and fall in others giving the homeowner an uneven floor.

Floor Prep

  • When carpet and pad are removed you would be amazed at the amount of dirt, sheetrock mud, screws, nails and a litany of other debris is underneath and exposed to the subfloor. Too often Metro Atl. Floors has seen instances in which builder grade “techs” (I use that word with a heavy heart as these individuals obviously do not take pride in their craftsmanship) do not put effort into clearing debris and preparing the floor, and simply roll the carpet pad right over the top of anything left on the floor. For a high quality and lasting installation, all of the debris items must be removed.
  • Once the subfloor has been properly swept we can now transition to inspecting the wooden subfloor for height discrepancies. More often than not there will be a joist that will need to be ground down at the high spots and have the low spots filled in. I cannot stress this point enough – DO NOT attempt to fill the low spots with cardboard left over from the wood materials, but instead use roofing shingles. The reasoning behind this notion is that cardboard will flatten out and degrade much more rapidly than a roofing shingle. Because of this, you may not notice a height discrepancy initially, but over time as the cardboard starts flatten you will notice uneven flooring. Roofing shingles are the preferred material to use because they have already been manufactured to be flat and are approved by the NWFA to level subfloor.

Hopefully this writing helped to shed some light on what goes into preparing a floor. For more information on the entire process we suggest visiting the NWFA website and our Flooring Blog, where you can find a wealth of information on the subject. In subsequent blog articles Metro will be providing further accounts on the rest of the flooring installation process. Stay tuned to learn more useful flooring information!

Proper Preparation For Wood Flooring Installation
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