Oh wow, I really do hope that is the case, echoflooring! How does one determine if the hollow sound is due to dips, or if it is due to adhesion problems? glennsfc, our substrate was flat to within the manufacturer requirements. The installers used a laser, and leveled areas with the appropriate concrete filler. If we were to use the injection technique to fill, where do we stop? There are seemingly hollow spots in MANY areas, not just one or two. There are so many spots - I'm guessing 30 or more.... thoughts?

If you have vacuumed and mopped, and you still have a dust/dirt film, I would mop it one more time, Changing water often. So your not just smearing dirt around. Know what I mean? If you run your trowel back and forth over the area, instead of just pushing a blob of glue, it will mix the dust in with the glue, and "key" to the concrete. LOL, seriously.

I am double posting this (from Design Dilemma) because I hope for professional flooring advice and also suggestions from people who've done this. We live in the Pacific Northwest (rainy winters and dry summers). Our house is 13 years old with ¾” OSB subfloors on joists 16” on center. We want to remove the carpeting in the dining room, living room and hallway (above grade) and downstairs hallway (on grade), and replace the carpeting with wood flooring. We also want to keep the height difference between these rooms and the adjoining tiled kitchen to a minimum. Because of this requirement, I am leaning towards 1/2" engineered wood rather than solid 3/4" wood. The new flooring would be professionally installed. Am I correct to say that OSB does not hold nails/staples as well as plywood for nail-down installation, nor does it provide a suitable surface for glue-down engineered wood flooring installation? Would glue-down installation avoid the squeeky-squeeks that might result from a nail-down installation? We have heard that installers recommend having an underlayment put down over the OSB to provide a better adhesive surface for engineered wood flooring and we would have that done. I don't think a floating floor would be an option because of the upstairs room size (50' x 15') and high ceilings (possibly too noisy). For glue-down engineered wood flooring, what underlayment would be best between the OSB subfloor and the engineered wood floor? How thick would it need to be? Thank you Mary

If these are Torlys engineered click together floors (with the HDF core) you are going to have concerns gluing down. Only if this is SOLID CORE hardwood engineered flooring can you look to glue down. The problem: HDF moves A LOT. It LOVES to expand and contract (as much as 1" over 25 linear feet....that's a LOT). The hardwood on top DOES NOT! If you glue down the HDF core product, you restrict a DYNAMIC plank. That plank will have problems. It will eventually rip itself away from the adhesive....the expansion forces will break the glue bond. And the glue is NOT grabbing the HDF....it is grabbing the CORK UNDERLAY. The cork underlay is the weakest part of the plank. Go ahead and pick at it with your nail. It crumbles after a few strokes. That's what the glue will be grabbing. It would only take one full "heating-cooling" cycle (winter-summer) for the bond to break. If you have installed floating floors with T-moldings before and "had no problems with it" then I suggest you keep going with that successful approach. Remember: "If it ain't broke; don't fix it," is something we all live by in the building industry.