Change in temperature = change in dimensions in the planks. Bamboo is NOT hardwood, therefore it has it's own issues outside of the normal issues with hardwood. And morning star has SERIOUS issues over time (go ahead and google LL and lawsuits....you will find DOZENS of class actions just waiting to go). I'm thinking this has TWO reasons for happening: Indoor living conditions. Something has changed and that needs to be looked at. 2. Improper install with not enough expansion left at the walls. As a floating floor, most of them will NEED transition strips at ALL doorways. Your FIRST priority will be to look at all your doorways (and pinch points such as hallways) to see if T-mouldings or thresholds were used. The SECOND priority is to REMOVE the baseboard in the area where this is occurring and MEASURE the gap between the floor and the drywall/vertical surface. Is it the REQUIRED gap? Go ahead and do this in an area that is UNAFFECTED and COMPARE the gaps. My spidy senses are telling me that a "too narrow" gap at install + change in household living conditions are to blame. The two put together have manifested itself into an issue. The fact that you have squeaks and the floor bounces tells me the subfloor condition was probably not dealt with to the degree needed to get rid of the noise. What is your subfloor? Plywood/OSB or concrete?

"Some worked, some didn't." It happens. Unfortunately what happens in new construction is framers don't put enough pressure on where they're fastening, especially with the use of pneumatic nailers today. They may spread enough construction adhesive on the floor joists, but once the plywood is laid, they run like heck to nail it home. IE: the adhesive isn't squeezed down in any consistent matter, creating voids that cause squeaks. I learned this while working on a job ten years ago. It was actually a warranty claim. The builder was found at fault because the framers didn't install the ply the right way. Not many do really. To them it's about getting the job done. Most don't even think about problems it can cause. The customer naturally wanted it done right. Hence, all flooring and sub flooring was removed and re-installed. Ken Fisher

Oana...it would take me a year of writing to explain the "sound" requirements they are asking about. So I won't get into it "too much". The SUBFLOOR PREP is what stops the 'hollow sounds' from happening. A 'dip' in a subfloor will mean a 'dip' in the underpad and that will mean a "hollow" sound every time you step on that area. Do the prep and you won't need to worry about "hollow". Skip the prep and the hollow sounds will haunt you. The STC/IIC ratings on materials are bung. Sigh. Sad but true. The testing parameters are SO FAR OUTSIDE OF NORMAL that NO ONE achieves the numbers they "achieve" in the lab. Your building's construction (the concrete or the plywood) will give you as much as 90% of the acoustic value. Yep. "59 dB" means absolutely NOTHING unless you know how your building was built. So that's why they are bung. The 1/4" cork underlay is a great way to continue a floating floor install. But prep is required. And fixing gypcrete is a MASSIVE battle. Huge. Frightening. Expensive and has been known to be made worse than if they didn't touch it in the first place. You ask your installer if they know how to (and have successfully performed) gypcrete repairs. If they look at you like you have two heads, simply thank them for their time and offer the "Don't call us; we'll call you" statement. And then find someone else. Gypcrete is a pain in the butt. That's the whole reason I suggested sticking with carpet. If you want a REAL opinion, remove the carpet to expose what is there and THEN bring someone in to give you an honest opinion of how much this is going to cost you. And it won't be pretty. Or get new carpet, list the home and sell it quickly.

G&S points out something that was bothering me about this install: OSB + Glue. Like G&S I'm HOPING the OSB is Advantech....but it might not be. And that's a whole 'nother can of worms. IF (big if) this is normal OSB (like the builder threw it down without knowing the final floor finish) that goes underneath carpet of floating flooring, then it might not be the "good stuff" like Advantech. OSB is FULL of glue and WAX...yep...wax. And just like wax from a candle, the wax in OSB can create bond problems with other adhesives. The reason why Advantech can be used in a GLUE DOWN install is the ability to abrade it (not many OSB products like to be sanded...they can get chewed up pretty quick). I'm not saying this is an adhesion issue. Without seeing how much movement that area has (you would know if the glue has let go...you would step on the boards and then would bend down under your foot like a trampoline), we are only guessing at adhesion issues. But what it does tell us is the METHOD or QUALITY of the build. Regular OSB as a subfloor underneath a glue down engineered hardwood shows a builder trying to cut corners. Now...a house built on sand with pillars in some areas but not others and a wood floor that has a sudden "hump" or dip that runs the length of an entire room. I'm going to bet dollars to doughnuts that the "dip" coincides with a joist. And that leads us to the next concern...settling. IF you are REALLY concerned about settling, you are welcome to reach out to a structural engineer. Before you do that, you will want to have ALL the soil testing results in-hand for your first interview. These should be part of the build or part of your ownership papers. You would have paid for it at some point (?built into the build price?). Go ahead and dig those out before reaching out to such a professional. If you don't have them or don't know if they were done (I'm not going there just yet...sigh) that's OK. The structural engineer can dig them out from city hall/building permits, etc....it will just cost a snick more in fees.