I don't have a picture (I can grab get one if you like), but I did the same thing in my current project - new wood floor in the kitchen going right into existing in the dining room. The floor installer feathered some of the new boards into the dining room floor so it looked continuous, then I had all the existing floors sanded and refinished and stained the old+new 1 color. The result is a transition that looks completely continuous and uniform. Of course I had to refinish all my existing floors to do it. If you don't want to do that the only thing I can imagine working is a perpendicular strip to edge the new and old. It'd be impossible to match the old stain with new perfectly so you'd need something to separate the two. I have a spot in my house where the boards are mismatched so whomever installed it back in the day put a strip. I attached a picture of that.

Had hardwood floor installed and the laundry closet has linoleum floor. Can't use matching wood transition because the gap between the wood floor and laundry door bottom is too small. Looking for advice to find the right metal transition with slope toward linoleum in the closet. Thank you.

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.

OK...the solid hardwood is factory finished. That's fine. It means that you can choose a solid factory finish so that EVENTUALLY you can get all of this refinished at the same time AND STILL end up with the same floor throughout. What you do is find the SPECIES of the hardwood and the width (and the thickness)...and if you can find the same grade/cut. Sure you can run it perpendicular to the hallway...so long as you are NOT on wood joists. If you have wooden subfloors the direction of the joists will dictate the direction of install. Regardless. So long as you get the same species in solid, you can always sand/refinish everything at once = same floor throughout the home. You do not have to do it today...but it gives you the BEST option to do it later if you want...or just before you put the house up for sale.