You have "sleepers" that the old flooring was nailed to. Your idea of 1/2" and then the new floor will work, BUT how much space is between the top of your floor and the electrical of the unit below you? Make sure your nails are shorter than this.

Redroze, I'm just getting back online and seeing your questions, so I'll try to answer what I can. My new floor in the LR/DR was not pre-finished, it was all site-finished. I did put a pre-finished floor down in my office (no pics, sorry) because I work from home and didn't have time to be without my office for the week it would have taken to have floor sanded etc. The pre-finished does have a different feel to it than the site-finished. I wouldn't say it's grooved, just a more defined difference in between the individual planks. The office doesn't adjoin any other room, except the tiled hallway, so I didn't worry so much about the wood being different there. I see from your pictures what you mean about running the planks the same way and wanting to be sure things don't look odd. One idea might be to take up some of your FR planks, like the first 12 or so, and then put them back down interwoven with the new planks. That way there's not a clear line in between the 2 rooms, but rather a more gradual blending. Here's another couple of pictures, this time of my family room. The first one is a before shot of the hardwood floor + a rug-like carpet. The floor created a frame around the carpet. I had the carpet taken up and new hardwood put in where the carpet originally was, then everything sanded and refinished. You absolutely can't tell where the old wood was vs where the new started. In this case, the new is random width because it opens directly to the kitchen (as opposed to the LR/DR which is all the same width). So, one house, all new site-finished floors in the LR & DR, all new pre-finished floor in the office, original/refinished in the kitchen, and half&half refinished + original in the family room. Boy did we have dust! Hope this helps! New:

The answer could be "Yes". It could be "No" or it could be "maybe...it depends". The trick with this is that new hardwood does not like sitting over top of OLD finishes...like polyurethane. And new hardwood needs FLAT. So the chances are VERY high that you need to SAND DOWN your old hardwoods (to remove the finish AND to flatten any obvious areas of concern). That should cost you $2/sf. Now the fun part...getting patch down where it is needed. It is possible but old hardwoods don't normally like to have concrete patch put down on them. They can. But they aren't fond of it. The cement patch often cracks and disintegrates as those old floors move. You will still need patch = $1/sf (on the LOW end). The other fun thing is: you probably have to install the floors perpendicular to the old floors....which will be AGAINST the installation instructions/warranty (most hardwoods must be installed perpendicular to the joists...which would be your OLD hardwoods...but the NEW one's would be perpendicular to THOSE = parallel to your joists = against all "Best Practices"). The way around this = DIAGONAL (lay it at a 45deg. angle). This should increase your WASTE into the 15% range = 15% more expensive than anticipated. So if you add up all the "trouble" you will go to, you will be paying about the same or MORE to do this. Of course you could throw down some plywood over top the old hardwood = go ahead as a normal install. But that puts you too high---so your ONE option to do this "cheaply" is not on your list. Go ahead and remove those old hardwoods (I'm assuming they are so OLD that they cannot be sanded and refinished). Lay new plywood and then install the new hardwood. The cost to do this properly should add $2-$3/sf (labour and plywood included). If you do this the "cheater" way, it should cost you $2-$6/sf (that includes the diagonal install with extra waste) and lose you your warranty. After all that money for the hardwood and install, that would be a sad state of affairs.

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