I would like to remove the highlighted wall on the second floor of my house in order to create a loft area.
Please help me identify if I'm dealing with a load bearing wall.
Disclaimer: I'm not a structural engineer, nor should you believe the word of a internet stranger. Contact a local structural engineer to take a look so you don't bring the house down.
A few details point to the wall visible in the photo being load bearing:
The blueprints mention a column in the corner instead of just letting them butt into each other. This is only needed when that column is supporting a load.
Finally the blueprints have that wall shaded like they have the outer walls while the other inner walls are blank. Outer walls are nearly always load bearing, while inner walls rarely are.
The walls around the closet are unlikely to be load bearing.
I'd bet it is bearing.
The picture shows a wall with a large opening and a door. I'll assume the plan view is the second floor plan.
In the picture you can see your knotty pine running parallel with the wall. This typically means that they are secured to the rafters and are perpendicular. The rafters are then resting one end on that wall. This is also why you see the beam spanning the opening - to support the rafters.
In the plan view you can see that the most likely position of the ceiling joists to span is from the outside wall to the wall dividing the bedrooms and again from the dividing wall to the wall you propose to remove. You could verify if you have attic access.
Like most have already said, I also believe it's a load bearing wall.. So for all the clues others have mentioned that it's a bearing wall, I also wanna add, and this may or may not actually be applicable here, but that it's common to hatch shear walls diagonally like the drawings show, so not only is that wall a part of your load bearing system, it may also be a part of your lateral system. I wouldn't touch it haha. If you're dead set on opening this wall up, I believe it can still be done with shoring and doing somewhat of an extension of that beam and adding another column. However, the height of those columns are pretty tall, I don't think the walls are the things bracing it from bucking, I think that's why they kinda "stiffen" it with the metal studs as noted on the drawings, but if it is indeed a part of the lateral system, that'd be really tough. Go find a licensed structural engineer though and they can tell you all the possibilities and costs associated! Structural engineers work for the owner and architect and their jobs are literally to make things work. If internet strangers tell you it's a load bearing wall, that's not necessarily a red light. A good structural engineer will probably tell you the same thing but also follow it up with solutions. Construction won't be cheap though.
Observations studying the drawing, 100% Load Bearing.
Section A will confirm further. Structural engineers will always span the shortest distance for timber joists. Taking out that wall, is physically impossible to do that without steel (span the floor over that is what I mean.) plus you would remove partial bearing support of the landing to the top of the stairs.
You could, to further be certain... Check the wall at the base by scrabbling back the render /fiishess to the masonry... And check for a dpc. If it has one, it means it requires substructure support... Aka... Foundation = load bearing.
If You decide to remove, prepare to either leave a portion of the wall nearest the external wall... 2-3ft...or put in a windpost to support the external wall.
Very educated guess (graduate structural engineer... 15 years in the industry). All the best. But definitely get a Structural engineer in who is local to confirm and Check the stability of your external wall should you proceed with the refurb work.