Ahhhhh....cost PLUS is in the fine print. It's how builders make a bid "look good" only to have the ability to add on as "costs" build up. See how that works? So...you need the slab to be relatively flat and level. A wavy/slanted slab will have to be dealt with. The *average requirement (the number we see MOST often for most floors) is 3mm over 3meters (1/8" over 10ft). The easiest way to "see" this is to use a 10ft level and "sweep" it across the surface of the slab. When it starts to teeter-totter you take the measurements. In 10 minutes you will have an EXCELLENT idea of how much work is needed. The laser measurements will be used for the full assessment. And PLEASE check to see that the glue they are using has a HIGH moisture barrier quality to it. Somewhere in the write up (on the company website) it should say "unlimited" moisture protection. Something like that. If it doesn't, you have a high chance of problems in the future. It could be tomorrow. It could be 20+ years from now. But the risk is there.

I routinely design installations with floors well over 1" out of true in 12'. I've had 1" in 6' happen. That's the reality of old houses! There are ways of doing this that do not impact the overall look. Designing the toe with extra room to be scribed to the floor is one way that works if you are creating a custom installation that features design details at the floor level. It does require extra skill from the installer, as it all rests on his shoulders to make happen properly. It's the same for the crown. If there is some sag in the ceiling, using a multi part crown, and planning for some drywall mud as well will disguise it to the human eye. This room is off 1 1/2" from one side of the kitchen to the other. Because the wall cabinets are in 3 separate sections, and the molding is a 4 part crown, and we fudged the backsplash spacing a bit, we were able to disguise it to 98% of the people that see the install. Without using custom cabinets, the only way to disguise the base cabinet issue was shoe molding, and a custom cut toekick to hide the shimming. If this were a custom cabinet line, that would not have been needed as m custom cabinet maker could have scribed everything to fit and then made custom toe details.

I'm not a fan of putting down plywood over concrete just so you can have a nail-in-place hardwood. Soooo many ways this can (and will) go wrong. Personally, if you MUST have a wooden subfloor over concrete, please use a sleeper subfloor system built properly with the proper vapour barrier used. Or in the worst case scenario, something like DriCore (I'm not a big fan, but it will work when done PROPERLY....ahem, I'll say it again, "when done PROPERLY"). You still have to patch the concrete. After that, you can use a vapour barrier (see how you can't get away from that?) then you lay the DriCore panels down and THEN you lay the PLYWOOD over the DriCore....and THEN you nail down the hardwood. Whew! Or you can look at engineered floating hardwood over a vapour barrier (there it is again) and a BEAUTIFUL cork underlay....like 1/2" cork would be AMAZING! As you can see, I will try EVERYTHING I possibly can to AVOID this type of subfloor system you are talking about. And I mean $5000 - $10,000 MORE to get away from it! That's how much I HATE the system you mentioned. Make sure your builder does everything properly (concrete patch, etc) and offers a LONG warranty on that subfloor system. Like 5-10 years (s/he won't like that ONE BIT). If s/he won't do it, then perhaps you would like to look at a different system.

Uh oh...,"...that's something I'll negotiate during the final billing." Sorry but that won't work. If they feel you 'won't pay' then they will walk off the job. If a company is so low on skill that it can't handle a ROUTINE subfloor levelling (this should be part of their daily bread...hmmmm) then they will be low enough on the honour scale to walk without a backwards glance. I guarantee it. You better get this sorted out BEFORE anything is touched. As soon as you touch this mess BEFORE things have been ironed out, you OWN the issues. I mean it. I'm trying to gently put my foot down FOR you...but it will still hurt you to hear what I'm saying. In building 'law' (depends on what state you are in) the 'last guy' who touches something 'OWNS IT'. Not kidding. If you allow SOMEONE ELSE to do anything to this floor without PRIOR WRITTEN AGREEMENT with the original company, you will be left hold this bag of whack-job-flooring install. Hash this out. Get it in writing and ORDER IN enough flooring to refinish the entire floor. 'Cause I can guarantee you will lose more than 50sf of wood. I expect a full 75% loss of wood. The glue on the edges will NOT let go. It will CRACK the planks to remove them. The glue is the TOUGHEST surface. The wood is the weakest. The weakest surface will brake...not the toughest. Please do NOT start this until EVERY KINK is ironed out and in writing with dates, signatures and WITNESS signature! I'm not kidding. If these guys can't figure out how to level an ENTIRE condo...then they won't be able to figure out how to 'save' a glue-edge floating wood floor. Assume nothing. Write down EVERYTHING. Preferably in emails...or write the email to the store reiterating what you spoke about over the phone. She who owns the most evidence wins.