Hi,
I'm installing unfinished 3/4" thick 2 1/4" wide solid red oak flooring.
Replacing old carpet that covers continuous 600sqft space in upstairs over osb subfloor. I'm nailing it with 2" cleats...going perfect so far.
Now about to reach the stair landing, and I'm looking to have a flush nose, so looking at buying something like this (unless there are cheaper options with same look?): https://www.llflooring.com/p/unfinished-red-oak-hardwood-3-4-in-thick-x-3-5-in-wide-x-8-ft-length-stair-nose-10023236.html

So, my question -- I understood I need to glue this piece down, but rest of flooring is on ECF underlayment. How can I ensure it'll be the same height? My plan is to install the nose first, which has a groove...and the planks I'm installing will reach it with the end grain side that has a tongue to slip in there securely. Also is there any issue to worry with expansion?
Thanks for any tips!

You can glue the underlayment to the edge where the nosing is going, then glue the nosing to the cork underlayment. Oak does not expand lengthwise, so tight against the nosing is good.

Hmm interesting - I didn't think that could be as strong as gluing it straight to the wood subfloor (the top side of the ECF is smooth too), and curious if now with two layers of glue the opposite issue (too high) will happen.

I also have a small 3x3 landing area where the floor will meet nosing on the long side of plank - would it be advised to use this same technique there? I'm guessing since the area is so small it's not likely to be issue & can expand towards the other side where there will be a gap with wall hidden by baseboard.

Thanks for your time!

The nosing does not have channels like the flooring so it can take less glue to hold it down. The channels will be more forgiving and be able to help the glue level out as you feed the tongue into the groove.

Actually ECF says not to use any glue with their product... so I still have this dilemma -- no one here used it before along with a flush landing nose piece?

There's couple photos here showing my current wood stairs landing, which is the same look i'm trying to accomplish in the ones i ripped carpet out from: https://www.icloud.com/sharedalbum/#B0W59v1AbGtabuN

Skip the underlayment and your issue is resolved.

Too late... the pic shows a small landing area, I could skip it there -- but I have a whole upstairs floor that is already installed on ECF ready to be connected to the stairs....somehow. So actually I want to use that small landing as a practice area.

I ended up cutting some 1/8" strips off an oak tread piece & then laying a bead of construction adhesive on those and glue to sub floor & then a thick bead on the floor nosing piece and smashed everything together while holding test floor pieces on top of ECF to ensure everything is level. Put a few 16 gauge nails for extra support. Can see couple pics here: https://www.icloud.com/sharedalbum/#B0WGQD2D7GFJcYp

Hope it will be OK... once it dries I'll start floor (perpendicular to it) - my only question now is should I also dab a bit of glue into the tongue of the floor pieces that will fit into it for more support.

I like to use glue, there.