I have just opened up a kitche ceiling that had been dropped and see now why it was this way. There is a 3 inch toilet drain running across the room to the main drain. I would like to move this drain into the joists that it is running under ( I think it goes under three or four) As it is 3 inch pipe that means it is more like 3-1/2 on the exterior so I now am exceeding the 1/3 depth that I read you should stay under if you drill through your floor joists. I can not be the first person to have this issue and I am looking for any experience someone may have had mainly as it applies to stregthening the joists in question. I can not sister them the full length as there are a lot of wires and some other plumbing in them also. Any experienced help would be appreciated. I live in Littleton Colo. Just in case our codes differ
Thank you

Hi Bailey...

Codes don't differ between states regarding this matter... ;) As you said, you can't exceed the 1/3 rule.

My first thought for you was to see if you can run the pipe up in the joist bay and reroute it so it ends up at the end of the joist bay where it can drop down the wall and perhaps be boxed out as it drops down into the basemnt(?)..

Otherwise, depending on where the hole is in relation to the span of the joist, you could lift that pipe into the joist bay if you add 3/4" plywood with the correct size hole on both sides of the joist. Here, you would extend the plywood about 2 feet in each direction past the hole... use construction adhesive on the plywood and then lag bolt through the joist and both pieces of plywood. You would lag bolt every 6 inches top and bottom. I don't recommend this, but have seen it done before, but only as a last resort and again where the pipe was not in the center of a 20 foot span, for example!!.

Anyway, that's my thoughts... back to you..

Mark

These are both good calls, I had considered the second but did not think of the first. Thank you for taking the time
Randy