We installed a floor recently for a customer who purchased the flooring from a company who sells but doesn’t install flooring. It was 1/2″ engineered flooring for a nail-down installation. When I saw the felt padding next to the engineered flooring he purchased I asked if the plan was to use the padding under the nail down flooring. He told me that was what the retail flooring supplier told him to use. The flooring store told him the padding would do four things: insulate the floor and keep it warmer, smooth out the imperfections in the subfloor, and make the engineered flooring quieter to walk on.
I suppose that is pretty much true, but that is not all that the padding will do. Let’s take a look at their reasons for recommending the padding.
First, the padding will insulate the engineered flooring, keeping the heat in. Heat rises, so you need to concentrate on insulating the ceiling first, then the walls, windows, doors and then the floor. The manufacture doesn’t specify what the R value of 1/8″ padding is, but I’m sure if it had a noticeable value it would likely be advertised. Plus, the fact that it is on the floor helps even less. I’d be willing to bet if you had two rooms, one with the padding and one without, you wouldn’t be able to tell which one was which from the temperature.
With regards to the idea that the padding would smooth out the imperfections in the subfloor. If there were nails or screws that were sticking up from the subfloor, it would compress the padding where they touched and help a little. Better would be to drive the nails or screws flush. If there was a high joint in the subfloor, it would also help a little but again — a better idea would be to grind down the high spot as we normally do before installing flooring over a wood subfloor. Remember, the padding is only 1/8″ thick (or thin, you might say).
With regards to ‘Making the floor quieter to walk on’: On multi-story floors, padding on floating floors inhibits the sound from traveling through the floor in one level to the ceiling in the lower level. An upgraded pad will reduce the hollow sound when walking on a floating floor. However, we are not talking about a floating floor in this case, we’re dealing with a nail-down floor. The metal fasteners will transfer sound to the floor below, and a nail-down floor shouldn’t have a hollow sound in the first place. If you were walking on the floor with hard soles on your shoes, I think it would be a little quieter.
So what did the retail store fail to mention? When you walk on the nailed floor the padding will compress slightly and cause the floor to make… “floor noise.” The joints will move slightly and make noise along with the fasteners, which very well may start to squeak.
I explained this to the customer and suggested he read the padding manufacturer’s specifications, which state: “Floor noise is not a defect.” (You have to go online to find that information, but it’s there.) He asked me why would they recommend using it then? Hmm, why would a retailer recommend buying anything from their store? I’ll have to research that one and get back to you…
The customer decided the flooring store retail clerks were smarter than I was, so we used the padding (and it’s hard to argue with that when they are walking on two legs and I’m crawling on my hands and knees).
Before we finished installing the engineered flooring, the customer asked me why I thought the floor was making “noise” in the hall. I told him it was just “floor noise.” (We started installing the floor at the hall so we had been traveling over the hall more than the rest of the floor.)
I’m confident that in a few weeks, the hall won’t make any more noise than the rest of the floor will.