How to enlarge hole around ABS pipe in floor joist?

[Johnnyh55]

I just moved into my first home and was hearing loud cracking noises and I didn't know where it was coming from, I have now traced it to the ABS drain pipe running in the basement ceiling in the floor joists expanding and contracting when we use the hot water. It's a 2 inch ABS drain pipe and I had a look at the holes in the joists and there is some room but on the wrong side, like the pipe is not centered in the hole and it binds creating the noise upon expansion and contraction. What type of tool could I use to make the hole bigger while the pipe is still in place? Is an oscillating multi tool the right tool for the job? I heard it would go through blades pretty quickly though? I thought about a reciprocating saw but I am afraid since it jumps around a lot and I dont want to touch the pipe.

Also, is the purpose of the hole in the floor joist to support the pipe? If I make the hole too big and the pipre is not supported by the hole, is that a problem?

 

[Terry]

I normally use a sawzall very carefully. I would not suggest that for a first time user though.
Sometimes the original hole was not drilled squarely, but at an angle which winds up causing the binding as the pipe heats and cools.

A floor joist can have a 1/3 cut and 2" needs to be left on the top and the bottom. If the enlarged hole is not supporting properly for grade, you can always use some strapping on it. Maybe even a small piece of wood screwed to the floor joist to support it.