Chatter marks or waves?

Q: We just had a wood floor company re-do hardwood floors. The first area was an office. Based on that experience we had them continue through the hall, kitchen and foyer. when they were done there were lap marks everywhere. Someone said that they were called chatter marks.

We had the company come back out and look at the problem and he said it was chatter marks as well and he said that the job was rated at an A minus. We cannot understand this. As the man was examining the job, (the actual worker who performed the job) was looking at the job, he made the statement that maybe his machine went out of adjustment. The other guy just tried to brush it off. We then called the actual owner and he finally came out to look at the job and downplayed the whole thing. Saying it was the nature of the beast and that if we put throw rugs and bring the furniture back in, much of the problem won’t be seen.

The office did not have this problem. There were a few spots of it, but that was all. This second phase is just polluted with the waves. The owner said that these were not chatter marks, that they were just by-products of the machine and a hundred other factors.

A: Chatter and “the wave” are 2 different things and can be caused by a number of factors. Chatter marks are very close together whereas waves are separated by several inches. Waves can be caused by something as simple as debris on one of the wheels on the big sander causing a thump as the wheel turns. Chatter can be caused by a loose sub floor just as an example. At any rate, regardless the cause, the only way to get rid of it is to sand the floor again. First the floor would have to be sanded on a bit of an angle to remove the chatter or wave. If the floor was simply sanded again in the same direction these marks would actually get worse. Clearly something changed between the initial area sanded and the area later. It has to be determined if it is the floor or the equipment.

Follow-up Q: I really appreciate you getting back to me on this. Is there a way to know if it is the floor or the machine?

A: That is a tough one to answer and will depend in part on the honesty of the one owning the machine. There are all kinds of things that can mess up a floor sanding machine drum. More often than not it will prove to be the machine which is not necessarily the neglect of the machine owner. Issues don’t announce themselves before they arrive. I’ve had several issues occur from flat spots on the drum to the drum being in a U shape so that the outside edges were cutting grooves into the floor. Didn’t happen on previous jobs and then there it was. We always need to give each floor a good look over to try and find tool marks. This is very difficult work and a multitude of issue can appear unannounced at any time. It is why even after 39 years each stain job in particular still stresses me out, not because I don’t know what I’m doing, but because I know what can happen.

If you have a poorly secured sub floor, joists spaced wider than 16” on center, to thin a sub floor, poorly nailed hardwood… any number of things can affect the sanding.

Follow-up Q: Just a few more questions if I may. In the flooring industry, is this wave a common problem- that people have to live with? Is it the contractors responsibility to re-do the floor? or does the home owner deserve to pay twice for the job?

A: I don’t know if I would say the wave is common, but every floor guy knows about it or has had it happen to them at least once. I try to avoid the blame game unless there is clear evidence of wilful neglect. I don’t know any home owner or floor contractor who would welcome having that issue appear on the job. Chatter can be either a machine issue or just as likely a floor issue. The floor is loose and vibrates resulting in chatter. Not the floor contractors fault, though if he sees it in time he may be able to work it out or lessen it with a polisher. Waves… that is more likely a machine issue and would fall on the contractor to fix it. I have waves once. I could not have that on my jobs. I went out and spent $7300+ for a new sanding machine. I was fortunate the home owner did not complain about it.