I've asked these elsewhere, but I think it got buried with another question.

For a new addition on our home, we are contemplating ways to tie a 3" drain into our main stack. The easiest and cleanest option is to run the drain through the floor joists. The joists are 2x12, 16" OC, spanning about 16'. Unfortunately the drain would have to run about 13', or through about 9 or 10 joists.

I've done the math and I think I can get the appropriate slope on this run without violating the letter of the code, that is to say, the hole being no more than 1/3 of the joist and no closer than 2" to the top or bottom of the joist, however it seems like a long run and I don't want to weaken the structure of the home.

The rooms above and below the joists are finished, so it is not an option to sister the joists from one end to the other. I have read about sistering the area where the hole is drilled with plywood or even steel plates.

The alternatives involve either jack hammering the slab (in a finished room) or running a soffit in a basement with ceilings that are already low enough.

Any thoughts?

Thanks!

Any thoughts?

Hi stubits

I mentioned sistering the joist. I should have said it doesn't need to be the whole joist from end to end. Just thought I clarify it from the other post you have.

Again check with the local inspector on what they will accept.

Maybe someone else here has a better Idea. For me even if code says. OK just drill I would still short sister existing joist.

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I think drilling the joist is the answer but I also think that you will have to put metal straps about 1/16 inch thick on either side of the joist and below the hole you drilled.

I think I would try to get some information from an Architect if I were you just to be sure.

You are correct: drilling 10 joists will create a weak spot in your floor structure. However, I would drill, then reinforce the joists. Specially designed and properly installed Simpson metal brackets would be one option, and running 2x4 or 2x6 along the bottom of each joists, one from each side, tied together with 5/8" bolts 12" apart would be other option. You may have to call Simpson people with this question. Simpson may even have these brackets ready made. Simpson is the leader in structural hardware industry. (http://www.strongtie.com/)

Thanks so much everyone.

Does anyone have experience with this product?

REINFORCERtechnologies | Metwood (http://www.metwood.com/products/reinforcer)

Milo- What do you mean by running 2x4 or 2x6 along the bottoms of the joists? Do you mean perpendicular to the joists? Just can't picture it?

I will try giving Simpson a call.

Although I plan on doing as much of this work as possible, we are engaging an architect to draw up the plans. I just want to get a feel for what's possible.

Thanks!

I'll draw you a sketch when I came back...

Thanks!