Bruce Locking Hardwood Over Concrete

Q: We recently decided to pull up our carpeting and install hardwood flooring on the rest of our home’s ground floor. There is currently Bruce engineered hardwood flooring that the builder installed using a glue-down method. Unfortunately, several of these boards crack and pop right at the threshold. We’re convinced that there was not enough adhesive used, and so decided that we would do a floating install for the remainder to be safe. We had previously done a floating install at our old house, and it came out great. However, that house had a wood subfloor.
So, we purchased the correct amount Bruce Lock-&-Fold flooring and the 2-in-1 underlayment from Lowes. We couldn’t find any Armstrong or Bruce underlayment, and just assumed that the generic brand they had would be adequate. We prepped the den by pulling up the carpet and pad, and removing the tack strips. We then put down the underlayment as specified in the installation instructions with the flooring and began laying the floor. We’re 2/3 done, and while the floor looks great it sounds terrible. It’s like walking on a bed of Rice Krispies, and the floor noticably depresses wherever you step.
We know that we cleaned and prepped the subfloor correctly, so we’re wondering if the generic underlayment could be the culprit? In looking through the Bruce installation instructions, we noticed that it calls for Bruce ComfortGuard, Armstrong Quiet Comfort or Quiet Comfort Premium underlayment. However, we can’t find it at Lowes or Home Depot. Will either of those underlayments take care of this problem? We noticed that you seem to recommend cork underlayment a lot, and we’re curious if maybe that would help our situation?
The project is currently on hold until we can figure out what to do about the sound and “bounciness” of the flooring. We’ve already spent quite a bit on this flooring. If we have to spend a little extra to get proper underlayment that’s fine. We’re just afraid that we’ll keep throwing more money at this and wind up with a floor that looks great but drives us crazy when we walk on it.
Thanks.
Ken & Crystal
A: With any floating floor there are a few things that you need to keep in mind. First of all, underlayment will only account for variances in subfloor height of up to 1/16″ and typically only the premium underlayments do this well. With the 2-in-1 and 3-in-1 underlayments you typically have a very thing and inexpensive foam underlayment, so getting quite a bit of noise and spring from the floor is common.
The Armstrong Quiet Comfort is a fairly good underlayment sitting a step below cork 3mm cork. In this case as long as your subfloor is rather even and does not need to be leveled, then the problem here is most likely the underlayment. I would suggest changing out to at least one of the suggested underlayments if not 3mm or 6mm cork or Sound 6. I tend to lean on cork as its natural density (amongst other qualities) removes much of the spring felt in most floating floors while also reducing the noise considerably, make the floor sound and feel much more like a nail down solid floor.
Keep in mind you will need to have a moisture barrier, so if you are using another foam underlayment, such as the Bruce/Armstrong stuff or Sound 6, you can leave your 2-in-1 in place then install the new underlayment over the top, but if you use cork, you will need just moisture barrier and I would avoid using the 2-in-1. The reason behind this is that the density of cork gets somewhat removed when a softer underlayment is laid under it, so it will have a bit more spring than the cork alone.