Clicking noise when walking on engineered wood floor

Q: An engineered wood floor was installed over a slab foundation in my kitchen/great room in March, 2007.
There is a definite “clicking” or “cracking” noise when walking on portions of the floor. It is VERY annoying and disappointing. I complained to the flooring company, and they had an inspector come out to inspect the floor. He only told me that there was no moisture problem. As I haven’t heard anything from the flooring company, I’m assuming the inspector found no fault in the installation.
What causes the “click” or “crack” noise when walking on the floor?
Thank you!
Sue
A: I’ve tossed a few emails back and forth with Sue to find out that this floor is an engineered floor made by Shaw, which was installed as a floating floor.
Usually when a floor is installed and has a creaking or cracking noise when walked over this is due to part of a wooden subfloor. Over time the subfloor can come slightly loose from the joists below and the slight movement in the plywood (OSB or other wood based subfloors included) will cause this noise. Normally what an installer should do before an installation is the check the subfloor and use floor screws where necessary to firmly anchor the plywood to the joists to prevent this type of noise.
In Sue’s case since this is over a concrete slab we get an entirely different dynamic, but a similar end. Urethane based (foam type) underlayment will eventually “sack out” as Gene D. likes to put it. Meaning that the product’s resilience will deteriorate and its ability to absorb sound will cease, meaning the slight movements of the floating floor will no longer be insulated by underlayment and thus the cracking noises. This process normally does not occur as quickly as Sue is encountering, taking years to occur rather than months.
Sadly here is a case where my preferred underlayment of cork could have solved a few issues. Some spare information I gave to Sue is to ensure she gets a written copy of the inspector’s report and to make sure you get a full record of everything installed in order to file claims as necessary if this is a case of a flaw in the underlayment or the installation.