500lbs safe on 2nd floor?

[CapnMac]

The early home didn’t have the fire blocking to stop draft that sends these old houses up in flames really fast.

Balloon framing used ledgers often notched in, and without adequate "fire safety" cuts in the joists and framing. They were meant to be predicated on being part of heavier timber framing. Platform "stick" framing has a huge amount of redundancy built right in.
Structural membranes are a marvel, but, they can be "cheated" all too easily. (koff pulte koff).

Mind, much of the rest of the world thinks we are nuts to use wood instead of bricks and concrete and inflammable roof tiles. But, it is what it is. So, we adopt, adapt, invent to suit the need of we gun owners.

 

[JFrank]

Yep
I think of old school ballon framing as a big chimney, now days as you say platform framing and fire stopping at every floor or ceiling line slows that fire down to a dedicated fire rating to give folks time to get out.
I won’t bore y’all with code talk just say that codes are minimum requirements.

 

[vintovka]

In Structures - like a structural engineer ? interesting there are so many different types of engineering degrees I can hardly keep up.
I carried my ICC residential building inspector certification many years but I enjoyed being a builder over inspecting.
My favorite thing is designing homes then bring that design to reality.

Yup. Can be fascinating but frustrating when cost, politics, nepotism and flat stupidity out weigh logic.

Long ago i invented a hanger that emulates a Simpson tie. In doing so i really learned a lot and gained an appreciation for modes of failure. Absorbing forces via shear is better than tension. Hangers beat the heck out of toe nailing and even end nailing. Beam or board depth is critical but failure at connections can be fatal.