What fittings can I use to re-route my copper DWV pipe?
I'm not sure why you need a flexible elbow. I'd use a 45 above the plates (near the insulation), bringing the pipe out of the wall plane, then a 90 to go right underneath the joists. Isn't it that simple?


If you find that the fittings are too long for that, use two 45s on the vertical pipe, one out and one back to vertical, but offset to the left (near the 22&quot; mark on your tape measure) so you end up tight with the wall plate (or its former position). Then a 90 gets you exactly where you want to be.


In all cases be sure to leave a small gap to the wood to avoid expansion ticking when you drain hot water. Cut and dry-fit all parts, then mark them as to position before disassembly.