Plumbing question about Drain

[fishermatt]

Howdy all, hope fishing is good!

I'm installing a shower (over joists) and I am about to cut the hole in the floor for the drain.

I'm finding that a floor joist is dead center on where I need the drain hole to be. I'd like to keep the shower right where it's at, so what are my options? What is the best way to deal with the joist and not have to move the shower out from the wall to get away from it. Thanks for any and all responses.

[sparcebag]

The proper way would be to head out the joist.Cut it back say 10 in. each direction,install a cross member that nails to each joist perpendicular,bout 32 inch cross member nailed to each opposing joist,then the joist you cut gets nailed to the cross member through the new cross member,its then headed out. to be safe on each cross member after there nailed in add a second cross member nailed to opposing joists and to first member creating 2 double headouts or cross members.

I'm hoping you understand my explaination.

[fishermatt]

I think I got ya Sb. After removing about 20" of the joist in question, I'll cut a 2X4 (aka cross member) to fit between the next 2 joists, then install the cross member with the top touching the subfloor, then nail it onto the cut joist (in the middle) and through the next joists into the ends. The second Cross member then installs just below the first one.

Same thing on each end of the cut joist.

Correct?

[Shack]

I there no way you can cut a "U" into the joist and apply a couple gusset's to strengthen. I know grade of the drain could be an issue though, but I have seen gussets and supports (2x4's running along the joist) work in the past and a slightly cut joist is better than a totally cut joist.

Do you have any pictures?

[sparcebag]

 Originally Posted By: fishermatt

I think I got ya Sb. After removing about 20" of the joist in question, I'll cut a 2X4 (aka cross member) to fit between the next 2 joists, then install the cross member with the top touching the subfloor, then nail it onto the cut joist (in the middle) and through the next joists into the ends. The second Cross member then installs just below the first one.

Same thing on each end of the cut joist.

Correct?

STOP If there TRUSSES your probably out of luck! Now I would move the shower base and fir out a wall,trusses are not forgiving as a joist,they are load specificly designed removing one like I said may weaken your floor TOO MUCH! 2x4s are bottom cords of trusses joists would be 2x8 or larger.

[fishermatt]

They are 2X10 joists (9 inches actual). I could maybe try the U tactic and see if I can make that work, and if not, head out the joist. I have crawl space below, so I can add support from the ground up too if needed.

Thinking if I had the drain stubbed in at 2.5 inches below the bottom of the subfloor, I'd need another 2.5 inches to attach the elbow going to the trap. I guess 4 inches of joist (with gussets) is better than none.

[Surface Tension]

When cutting into a floor joist there are some rules. Can't recall by memory and don't have the formual handy, if I were a plumber I'd know it without needing reference. Location along that span matters. What you propose to do is worse case. A plumber will step in I'm sure and give you a definite answer.

If I were on the job and had to spend more then 10 minutes on the finding out, I'd spend less time and have my hind end covered with this.

Use hangers too.

[reddog]

To properly do this, Surface tension has the right detail. It entails sistering another joist to the joists you are expecting to carry the weight if the joist you cut

[sparcebag]

The detail surface posted is correct,However the double joists only need to be in place when the span is 4 ft. or greater,If ya cut out 2 joists or more,the double heads cross members have to be in place.No 2x4s use the same size lumber as your joists.

No you cant drill a joist vertically,but for horizontal pipes ya can with in 6' of bearing wall the hole cant be more than 1/3 the depth of joist and located on bottom 1/3 of joist. I believe the hole has to leave at least 1" of joist on the bottom.There are a few circumstances where holes can be altered,there site specific.

[fishermatt]

Surface T,

 Quote:

Location along that span matters. What you propose to do is worse case

Regarding the location along the span, it's 4 feet from the outside wall on a 16 foot joist.

From the resposes, here is my plan:

I should only need to cut out a chunk about 4 inches wide and 5 inches down, so I'll have 4 inches on the bottom of the joist that I can screw 2X4's across on each side, and put cement blocks under that to hold it up more. Thanks for everyone's replies.

[Redlantern]

If it were my house, I'd either header off the joist or shift the location of the shower by two inches. To me, it's just not worth going to the trouble of putting in a shower and then holding the joist up with cement blocks. When it comes time to sell, you probably will turn off a few buyers if they look closely.

[Surface Tension]

You want to avoid putting a block to the ground under a joist. Under rim joists and girders, headers yes because they are part of a system. In addition, all those are equal in that they float or have footings you can't mix the two.

A block under one joist is not part of the support system and when theres movement from either the system or block that one spot in the floor will sag or bump up.

Thats a very large chunk taken out of a long span. The 5"s taken out will not be made up with with 2x4s sistered to the sides of the joist. Doing that might be "fine" and I'm making a big deal out of nothing. I've worked in the trade for a long time and have done a ton of remodeling on old houses and have seen practices that wouldn't fly by todays codes, still the house is structurally fine.

We've talked about two ways of doing that both share the load with the existing floor joists. In the remolding world sometimes you have to revert to other methods to get the job done.

I can add a couple more that will work but without seeing the job I can't say what would work best. Sister on another 2x10 the entire length supported by the existing system. Your notch should less dramatic if you do that. Or add another joist next to the one you have to notch, then add solid blocking every few feet between the joists on both sides of the notched joist.

[fishermatt]

I have no problem with heading off the joist if that's the best plan. Point taken about bracing from below. I will not do that. The joist is dead center on the drain hole, and I don't have room to move the shower out from the wall further.

Forgive me for being greener than a freshly sprayed christmas tree. Having you guys to ask is an amazing help to my project!

Thanks again.

[Redlantern]

Maybe you're green but you have enough common sense to ask good questions.

[fishermatt]

I headered off the joist, with double cross members. The shower is all in, all done. Except for taping the sheetrock. that's one thing I don't have the touch for. If it weren't for PEX, I wouldn't have tried plumbing either. Thanks to everyone for their help!