Echo is right. Especially with a dense species this is a crap shoot. And the comment about the slab being dry only applies if you have a good moisture barrier under your slab. What I mean by that is if you take concrete readings and determine your slab is dry that only means it is dry at that time if you don't have a plastic barrier beneath. I've seen a lot of concrete contractors cutting corners and not using it in different markets and they are telling their customers that they have an additive in the concrete that keeps it from wicking moisture from below. I'd be very careful. Either use a product made to be glued to a slab and use a moisture barrier or deal with the height difference and make sure you get a good barrier on top of the slab. My two cents.. realwoodfloors.com

Okay, I think you have all convinced me to not create my own weekend from hell (by trying to pour leveling compound with just two adults ... and two kids under the age of five). Thanks for this! We have the hardwood on hand, and were already planning on a floating installation as it's recommended for the product (no nailing). So if we now switch and go the cork path - say with that 12mm option from the website you mentioned - that leaves me with a few questions: (1) My previous calculation - indicating the top of the hardwood surface would be almost half an inch lower than the top of the adjacent tile surface - had built into it using 3mm PergoMax underlayment (the "gold" stuff). Would I still use this stuff, on top of the cork and underneath the hardwood? I'm guessing no. (2) Perhaps tied in with the first question, I see that thinset is used to adhere the cork to the concrete. Is this correct? This will (obviously) add some thickness to the whole equation. I'm thinking now that - by removing the PergoMax stuff (-3mm) and adding thinset (guessing, +2mm) - it's pretty much a draw, which I then just float the hardwood on. Am I thinking of all of this correctly? Thanks again for all of your help. You are all much appreciated.

SJ McCarthy, our contract is stated we are responsible for the materials and we pay for the labor. Unfortunately we never met nor discuss with the owner but only discussed in details ( in the proposal) with the project manager who is the solely the carpenter.) We just found out there were a lot of the DETAILS from the proposal were not explained (per the PM,but who knows) in detail to the owner or almost like "bait and switch" - for example like item #2- he spent more time because the owner did not get him another helper to help him- I told him this should not be the customer's expenses-Anyway we are willing to pay for it. The owner was offering to renew and establish a new contract from the original contact ( we felt that he cherry picking the items from the proposal, we marked them up then again he decided not to included) for the unfinished works . Once he agreed in our 2nd meeting (another example: he agreed tiling our study room to be included from the original contact in our 1st meeting then when he write the REVISED CONTRACT- he wants to charge us ), but again we are facing the same old stories-he tried to change the wording. We were burned so many times and now we diligently review line by line knowing the owner's personality. He kept saying he lived by the contract-then I told him then he should honor the low estimated to install our engineering hardwood floor including removing the carpet-in the end he says he would honor but he did not including the cost in the new REVISED contract which we add into it - we are so tired with his games. So now we put a contingency - once we agree with the new contract, no more additional expenses from the previous work was done- and we do agree that we need to be notified first and need both signatures for additional expenses from the new contract. and no more point finger of "not included" since we have discussed in detailed and are in the contract. The new addition has a hardwood floor installed - with Dri-core. Once hardwood floor was installed- they are some areas squeak- we were told by PM -put a marked up then he would fasten without explaining to us-these would be additional ridiculous charges (PM told the owner, too-we told PM that they should explain it to us- ) Regarding the installing the engineering hardwood floor is for our existing rooms(concrete slabs that has plywood already)- we are told just to put a vapour barrier. Is it possible to let me know what brands for the glues have to be moisture resistant ($2/sf) or moisture PROOF ($3/sf).? The manufacture instruction suggests to use Franklin Tongue and Groove adhesive (cross linking polyaliphactic emulsion glue) www.titebond.com -any suggestions? This Applachian engineering hardwood floor - FLOATING only needs GLUE between the wood (tongue and groove per the manufacture manual ) then would be FLOAT - this is not to be GLUE DOWN on our concrete floor (could be glue down if necessary but not in our case). Here is the website- on PAGE 9 http://www.appalachianflooring.com/uploads/general/documents/engineered-installation-guide.pdf We trust the PM and we pay for it- we just want to move on and complete the project-It has been almost 10 months. We have to do what we have to do to protect ourselves now- The owner refuses to install our towel bar in our new shower without charging us, and we told him we will take care them by ourselves. I will update this post and hoping for a better solution. Thank you

Please do NOT install over hardwood. I don't care if it is glued down over concrete or nailed to plywood. Vinyl and wood FINISHES do NOT work together. In fact the chemical transfer (and this is the LEAST of your worries!!! ahem!) from the wood finish to the vinyl is almost 100% guaranteed. That chemical transfer = heavy staining of the vinyl. And heavy damage to the wood floors underneath. Which renders BOTH floors unusable. And if the new owner finds out about the damage to BOTH inside of a year (or two...depends on your State's liability laws) you will STILL be on the hook for the damage/removal/replacement. The BIGGEST issue is NOT the staining - when dealing with glue-down hardwood over concrete. The BIGGEST issue is moisture damage and mold/mildew contamination. Concrete breathes and gives off moisture. The adhesive used to glue the wood is a moisture barrier but it never really 'cures'. It stays flexible. When you put vinyl over the wood you CAP the moisture. You TRAP it. That bit of moisture in the GLUE then soaks into the wood...that wood stays soaked and NOW you have huge amounts of mold growth. The chemical staining of the vinyl then SPEEDS UP. Instead of taking 5 years to stain the vinyl (over plywood subfloor) the soaked wood causes the chemical staining to occur in 1-3 years. That's when you pull up your vinyl to find the soaking, molding, useless mess. Now you have to do it all over again but this time with MOLD REMEDIATION costs added in! It's your call. But the installation instructions clearly state not to do it. They don't do this to p!ss off customers or to cost the homeowner more money. They do this to PREVENT irritation and to PREVENT greater costs later on. You wanted vinyl. You currently have hardwood. You will need to pay the piper to get this done properly. Of course if you used laminate you wouldn't have this issue. You could have run the laminate right over top of the hardwood without issue....just sayin'.