Help deciphering framing in pic

[TaskBoy]

This was on another thread in another area but I didn't get any answers as to what I am looking at in the pic, so... This is inside a soffit/dropped ceiling between a 1st floor bath and the second floor. Ceiling is about 6 inches lower than rest of house (bath ceiling 7-6 and rest of house is 8-0 ceilings). It's looking toward an exterior wall about 3 feet from the camera.

I'm mostly trying to I.D. the rim joist. The rim joist is the second joist in back (you can barely see its bottom edge), the question marked wood is the top plate, sound right? Thanks!

 

[inspectorD]

The rim joist is always the joist on any outside wall. Does that help?
The top plate is the 2x4 which is directly under the rim joist. Usually there are 2 of them stacked on each other.
Going to the library to get a book on platform framing is the best idea I have for you to learn terminology.
And to get some ideas for projects.
Good question.

 

[TaskBoy]

So, did I identify the items in my pic correctly?

 

[inspectorD]

The rim joist or box joist ...is the outer-most joist. You will not be able to even see or touch the bottom of it because it sits on the 2x4 top plate. The one you have pointed out may be that joist but I cannot tell from the picture.

 

[TaskBoy]

Hi I know it's tough to tell in that pic. I had to hold the camera in as far as I could and shoot blindly. I do believe the 2-2 x 4s are the plate as the ceiling is dropped about 5.5 to 6 inches lower than the rest of the house. With that in mind, I'm guessing that joist in the background is the rim joist. Everything seemed to jive measurement-wise: the floor-to-ceiling, the space between the ceiling and the second floor, the various timbers and how their measurements added up...

I will take many measurements and then drill a small hole from outside to see where the light shines in thru. If I'm right, then I'll cut my duct hole. If not, I can patch or adjust as needed. Thanks.