Apologies if a question like this has been asked and answered already, but I’ve searched in a few different DIY forums and haven’t found anything that specifically relates to my situation.

I recently purchased an older home, and am looking to carpet the 2nd floor. I’ve got some adjustments to make before I can have someone come in and install the carpet (apparently Home Depot can for cheap when you buy more than $500 worth of carpet from them).

Anyway, I’ve also got some decisions to make as I prep the area for the installers. Here’s the overall layout I got when HD came to do their estimate:


I’ve got a rise of about 2.25” over the approximately 4’ of run directly to the left of the bathroom (labeled as “M/BTH”) in the diagram. Here’s some pics:



As you can see, I’ve got a subfloor of ¾’ X 3” T&G planks throughout. As I found after I did a little demo, the area in that bathroom hallway area has sunk quite a bit, and started out (when I bought the place) as planks + what looks to be 1/8” plywood + ¾” plywood that was “shimmed” by some 2x4’s as the hallway sinks to keep it level + cork tile on top.

The rest of the rooms themselves (labeled BED1, BED2 and BED3 in the diagram) are all fairly level, with all those same 3” planks, and what appears to be more of that 1/8” plywood covering all of “BED3”.

So as I prep the floor for carpeting, I have 2 questions:

-what’s the best solution for that section of hallway in front of the bath?
-do I need to put down plywood over those planks before carpeting? From what I can tell, they’re screwed right to the joists, and were painted at one point. But I’ve read differing opinions about what’s necessary for subfloor when carpeting.

Appreciate any advice you all can give me – just so long as it’s not “tear it all out and start over”

Thanks in advance!