Do tile. There is no good long term way to use solid wood over concrete. I’ve seen the rotten plywood underneath when it was removed for having cupping issues.

Thanks, but this is exactly the answer I was hoping not to see :). I would really like that continuous look of the wood to make my long and narrow townhouse look more spacious. I just checked and I would be able to source the same type of wood also as engineered with a 4mm wear layer. Could that be a workable solution? Thanks.

As Greendesigns points out, laying hardwood over concrete is tricky. A permanent hardwood (glue/nail/staple) on slab is more likely to go wrong than right. To be crystal clear, you can GLUE DOWN hardwood STRAIGHT to the slab.

Adding plywood is a step used to NAIL down (or cleat/staple) hardwood into place over slab. You can SKIP this part if you GLUE DOWN the wood. But....and this is a MASSIVE 'but'....the professional must be SUPER EDUCATED as to glue down technique, glues, trowel size, coverage, moisture mitigation, etc, etc, etc!

Gluing down hardwood is no different than gluing down plywood. Both are wood. Both require the same adhesives...and both have the same failure rates (ie the 'rotten plywood' comment above).

The next issue would be height variation. I would expect a transition. Even a small one. And the reason: the townhouse subfloors were BUILT to accommodate cork glue down tiles (probably 4mm) in the kitchen and then another floor in the living space (???original floor???). And this BUILT IN floor height variation will never go away. Not unless you go back in time and make all of your decisions based on the inclusion of the hardwood running into the kitchen.

I personally would find out if the engineered hardwood (with the 4mm wear layer) can be FLOATED - most are allowed to float...but not all so it is best to be super prepared. If it can be, your situation has been solved....remove the old vinyl/cork and FLOAT the new hardwood in the kitchen.

A thin sheet of plastic will be laid down over the concrete and the wood will be floated over top. You will have a small transition ANYWAY (floor height variation = transition) so you might as well change the type of install to MATCH your slab = floating hardwood = MOST APPROPRIATE form of wood flooring install over slab.

Also be aware that the finish might have a slight colour/gloss variation. Again, that's where a well prepared transition strip/area can be SUPER helpful in hiding these slight variations.

Thank you for your responses Sj McArthy and Uptown floors. I am aware that going with the engineered wood would inevitably lead to a transition piece, but I have pretty much come to terms with the fact that I will most likely not be able to match the heights exactly. The reason I wanted to find a way to install the hardwood is also that I have about 100 square feet left of the exact wood we installed in the rest of the house. This is unfinished rift and quartered red oak stained on site and thus matching the color should hopefully not be too much of an issue (the engineered wood would be unfinished and from the same mill too) and the expansion differences between engineered and solid should hopefully also be smaller given the wood is R&Q. I will definitely approach potential installers, starting with the ones who did the rest of the house, but I wanted to educate myself somewhat on my options first. The input you have provided is extremely helpful.

I'm trying to find a type of floor for my living room, on a concrete slab, obviously I can't do tiles, anyone can help?

Perhaps start your own post and you'll get more answers. With the right underlay, you can use vinyl, laminate, cork or engineered wood.