Hardwood Floors February/March 2026

AT THE SITE Common Mistakes with Concrete Substrates (Continued)

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NOT FLAT ENOUGH We all should be familiar with the NWFA flatness standards for a concrete slab and for any floating floor installation being 3/16” in

10’ or 1/8” in 6’. This is a minimum standard that “may” be good enough, but with some installations, it also may not be. Keep in mind that what you can get away with on a nail down over plywood installation is quite different than a direct glue down on concrete, which is why the flatness standard is even looser (¼” in 10’ or 3/16” in 6’) for this application. Very few slabs are flat enough to not require any additional prep. Knowing how to measure for flatness is obviously important. A 10’ piece of straight material works at a minimum (provided it is actually straight). You also can use lasers, string line, a story pole, or gas levels. There also are systems that will give you digital results direct to your phone and even software that will give you 3D modeling of your subfloor. Again, if you are not familiar with how to determine your flatness, get to a training. The NWFA, and many manufacturers, offer training on how to measure and address flatness of a subfloor. What you will learn will make you look more professional and help reduce your failures. With today’s very educated and demanding consumers, “good enough” is less and less good enough to keep you out of trouble.

ABOVE AND CENTER: Two examples of an ill-prepared substrate.

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NOT PAID ENOUGH One of our industry greats, Lon Musolf, used to say, “If you don’t have time to do it right the first time, when will you have time to

do it again?” I will parallel his statement and say, “If you aren’t getting paid enough to do it right the first time, who is going to pay you to fix your mistake?” The simple fact that you’re reading this article says you’re a step ahead of the contractor who doesn’t. The fact that you invest your time and resources into attending NWFA and manufacturer training places you ahead of the contractor who does nothing. If you are worth more, then charge more. Period.

An example of a well-prepared substrate.

PHOTOS COURTESY OF DON JEWELL | LOBA-WAKOL LLC

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