What is going on under my floor, and best way to shore up damaged floor joist?

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New Member
Apr 5, 2019
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Hello all.

I'm getting ready to have some framing done in my basement. I previously ripped out the drop ceiling, some wall paneling, and the insulation in order to do pest exclusion.

The house had termites in the past (I now have that taken care of) and I found a single floor joist that is pretty eaten up on the end. I was told I could sister it. I read online that I can run a whole new full length joist and attach them, but do I need to do that when only about a foot of one end is damaged? How would I go about shoring that up?

Also, I'm attaching some photos of the area near that joist. It looks like the builders cut out the subfloor or whatever around that area. I think this is the area around our front porch. I see tons of spiderwebs and I think this is one area mice have gotten in in the past. I plan to stuff everything with steel wool and then use a pest repelling expanding foam to seal it. Curious why this would be like this. This is the only area that looks like this.

Any thoughts or advice appreciated!