Cracked Rim Joist, Not Sure if I Should Care?

Question

I was putting some insulation in between the joists in the basement, figured I might as well since I was doing some remodeling.

I found this rim joist to be in poor condition when I was working:

This is a joist right under the entrance, I'm wondering if in the past some sort of flooding occurred upstairs and it dripped through the crack below the door.

Anyway, I saw something here, which seemed to indicate that these cracks aren't that important, but this one looks bigger than the one in that forum.

Anyone familiar with this have any ideas, or maybe where to start?

Answer 1

Rim joists are more to keep joists from tipping/moving and to close in the ends.

That looks like a second piece of wood added to the top of the joist. Different grain, so not a crack.

They might have used a smaller sized joist, a 2x6 instead of a 2x8 and added a 2x2 on top, or there was some damage to the top of the joist that was cut off and a 2x2 added.

Answer 2

What is called a "rim joist" is sometimes called a perimeter board. it normally does not carry any structural weight and only serves to seal the ends of the joists on the perpendicular sides. See attached image. The perimeter board on my house is just OSB attached to the ends of the floor joists.

The floor joists carry the load of the floor to the sill plate that is then transferred to the foundation for the structural load of the house.

This looks like someone just tried to fill a gap with a different piece of wood as #crip659 pointed out.