So, to make a long story short, I decided to replace the carpeting in my main living areas of my condo with hardwood floors as an attempt to improve marketability (selling in about a year). Because the subfloor is gypcrete, a floating floor was the only viable option, based on my research. Upon tearing up the carpet, my contractor and I noticed that the subfloor was not in good shape - unlevel and lots of cracks. My contractor was convinced that he could level out the subfloor and make it work. Two floors later (the first floor had other issues from the manufacturer), there are still several areas where the floor "flexes" quite a bit, even to move furniture like end tables. Upon consultation with the contractor, he insists that "that's the way it is" and that my subfloor is "challenging" and there is nothing he can do it. He kept telling me that he used a "6 foot leveler", etc.

The flooring used this time was 4 3/4" bamboo engineered wood flooring with click and lock system, no glue.

Is there a way that I can repair only the areas where there are issues? I don't mind if a large chunk around the region has to be taken up, but I am trying to avoid ripping up the entire floor (expense is an issue, of course). What are recommended ways to fix this problem? Simple "spot" leveling? Extra padding? Shims? I will likely have to hire someone else to take care of this problem since the contractor doesn't think there is an issue, but I want to get information beforehand so I can go into this with some knowledge. Thanks.

Getting a substrate flat is not rocket science, but it can be very hard to do at times and takes patience and planning. We are supposed to use either a 8' or 10' straight edge, but an experienced guy/gal can use a 6' if they know what they doing. We start out by going over the entire area and drawing out a map marking the high spots and low spots. It is best to deal with the all high spots first, then map the floor all over agian.... because the low spots are going to move or just disappear. You just keep repeating this process, taking off high spots and filling in the lows until it is adequate.

If you don't do it this way it's like a dog chasing it's tail and you will usually up with a mess. Apparently your contractor has thrown his hands up so I suggest you try to get a more experienced guy/gal view it in person or you can hire an independent inspector to assist you.

Larger outfits than me will use self levelers with pumpers and a crew to do do this no problem after damming up all vent openings, doorways, ect. Since I work alone I use the slower method.

As Jerry has indicated, leveling is a project that will require full exposure of the sub-strate, at least room by room.
These lock floor systems can be fairly easily removed, and re-installed. I recommend that you proceed with that process, to facilitate the leveling.

So, if my floor has high spots and low spots, should the high spots have been ground down? He definitely did not do that. I have a sizeable "hill" in my living room up to the patio doors, and he said that there was nothing he could do for that. Of course, that is far from the other problems, but that area is a separate issue.

By the way, this is gypcrete...

I'm aware it is gypcrete. I have never encountered gypcrete on any of my jobs, but I have ground down or scarified many concrete substrates. I'm assuming gypcrete would grind down easier than concrete, and it is entirely possible the best solution would have been to use a self leveler over the whole floor from the getgo, but that is is impossible to tell from a monitor. I should step back and allow someone with gypcrete experience give you better advice than I could.

Gypcrete will grind easily. It is important to lower the "hill" as much as possible or you will need a lot of leveling compound to raise the surrounding areas.
So, in short, lower the high spots first to reduce the amount of packing of low spots.

Don't use a portland cement to fill, over gypcrete. It will blow off the gypcrete. Use something like ARDEX GS-4

OK guys it's been a couple of months. Things haven't gotten much better. The same old story is coming from the installers - that is the way it is and I can't do anything about it. I don't want to bad mouth them too badly because they did phenomenal work on my kitchen and bathroom. This floor, I feel, is just a super challenge.

Anyways, I called some other guys to come out and assess. One guy says he can put shims under some of the loose boards to make it more stable. Another guy proposed a more "permanent" solution - take up the whole floor, lay down 1/4" cork underlayment to the gypcrete subfloor, and then glue the bamboo engineered wood floors to the cork underlayment. Two different answers - two different price points (of course).

My fear with going with the cork/glue down solution is that I am not sure what reprecussions will occur because of the unevenness of the subfloor. The guy proposing this looked over the whole floor and called it a "mess" and said that he would also level out some of the low spots as well. There is still the matter of the "hill" in the living room bucking up against the outer wall, but I have given up on that. I just don't see a way of getting that to cooperate.

Anyone have any comments or opinions about either the "fix it" option or the more permanent solution? I really would appreciate any and all help on this. The floor is so nice laid down, but walking on it is becoming annoying.

The reality is, and what everyone has already explained, is the substrate must be flat to begin with. How you get there is what matters. It appears the entire room of flooring will need to be removed and an accurate assessment of this gyp-crete underlayment needs to be done. Keep in mind gyp-crete is a non-structural underlayment used for fire and noise suppression. It is probably only a few inches thick. And more than likely, it is loose in places from the actual subfloor, which is probably plywood. It maybe possible to remove all the gyp-crete from this one room ( where the problems exist ). And then have more pumped in and leveled well so a floor can be installed. It may also be possible to flatten this mess by grinding the high spots and filling in the low spots. What you cannot do is remove the gyp-crete and put in a flammable material ( like cork or wood ) in it's place. The building code in a multi-family structure requires certain fire suppression measures to be taken to help prevent the whole building from going up in flames if one unit catches fire. Either way, this is not a job many flooring contractors would be interested in. I had a similar really screwed up slab to deal with a while back. It was beyond my ability, resources and I had no desire to fix it. Instead, I got a real good tile setter to come out a "float" the entire mess like he was planning on setting tile. Sometimes, multiple trades need to be employed to resolve a floor issue.

^Thanks Gary. That is what I was thinking myself. Laying down the cork is not going to correct the unlevel mess that is in this place, and that is ultimately the problem here.

Does anyone have any suggestions about who I should go to to try to fix this? I have asked flooring people and had a general contractor who originally did it and couldn't fix it (obviously). Is there a "specialty" I should search for, or call on another general contractor? I am just not sure who to ask for advice about this right now.