Hole in floor joist.
 

Repair five inch hole in 9 x 1-3/4 inch floor joist, inspector wants it the length of basement.

Ok, so is there a question in there someplace with the little but of info you provided?

Ayuh,.... 'n how long might That be,..??

The length of the basement...

How long is the basement?

The same length he needs the floor joist.

I hope this helps.

Andy.

Sistering the joist the full length with it bearing at both ends is a prescriptive method. If you want to do less, that would be engineering a fix and the Inspector will likely tell you to have a design professional, e.g. licensed architect or engineer, specify that fix. It is easier and more economical to just sister the joist the full length with it bearing on both ends.

Let me guess, Home Inspector? If it is a building inspector for the city or county, you are at their mercy and have to do what they say. If it is a HI, tell them to show the documents backing up their statement.

Really need to post pictures showing this. Make sure that you stand back and do not zoom on the joist with the hole, just take a picture and post showing the surrounding area with that 5" hole and associated joists.

Whether or not the 5" hole seriously weakens the joist depends on its position along the span. Quite probably, there is no structural need to sister the joist along the whole span but, as you have been advised, that would be cheaper than getting a SE to prove by calculation that whole-length sistering wasn't structurally necessary.