Installing 3" drain in Joists during framing

[Zimm0who0net]

So I'm looking at the drawings and there's a run of about 14' of 3" drain for a toilet that needs to run through the floor perpendicular to the I-Joists. The I-Joists are 14" high, 16"OC. So I'm thinking there's zero chance of finagling that 14' stretch in there, so I'm either building it after the fact with 10 different short pieces coupled together, or I'm installing it during framing as one long stretch.

Am I missing something? How do you'all professionals deal with this situation.

 

[Terry]

I would run it with the floor joists, not against them. Planning for the 3" needs to fit with the framing. Sometimes I will box in a corner if needed for things like heating ducts and pipe runs.
Pipe will bend some. That may be a help.

 

[Sponsor]

 

[WorthFlorida]

Check the print very closely. It might be to run under the joist and would then need to be boxed in. Usually not wanted if this is the second floor level and a finished ceiling below unless it is a garage or crawl space. Otherwise as Terry suggested, the pipe must be run differently.

 

[Zimm0who0net]

It's a tough location. It's the 2nd floor and all the plumbing is along a wall that's supported by a beam, so there's no wall below. The sewer comes in 10 joists away. If I run with the joists I'm going to the far wall which is 25 feet away (which gets me really close to my limits on slope in a 14" cavity) and then I'll have to come down through the slab and back the 25 feet to where the sewer comes in. Here's a link showing the issue. https://i.imgur.com/rA0dzbA.png

My thought was to drill the joists before they're installed, put a section of 3" in through all the holes, and then drop the set of them down, all during framing. That way I end up with a nice run of 3" perpendicular to the joists. The alternative is running things up to that point to the right and then coming all the way back under the slab.

 

[WorthFlorida]

https://diy.stackexchange.com/questions/10657/what-are-the-guidelines-for-holes-in-joists

You’ll need to check with your building department and manufacture of the joists of max size of holes can be. A 14” spec I-joist by the architect probably was for 3.5” holes to be with in limits.

 

[Zimm0who0net]

They’re i joists. You can theoretically cut an 11” diameter hole in a 14” high joist so long as you stay far enough from the ends and other holes.

 

[Reach4]

Do you have an architect or engineer? Check with them. Otherwise check with the makers of the manufactured joists. If regular wood, I don't know if you can drill those 3.625 holes to pass the pipe without weakening the joist too much. If your hole is only that big, your holes would have to be precisely positioned to pass 3 inch PVC.

 

[wwhitney]

Can you drill the rim joist and just slide in your 3" pipe from outside?

Cheers, Wayne

 

[WorthFlorida]

https://www.apawood.org/i-joist

Zimm: as you stated above pre drill. The framer and plumber will have to work together. Pre-drill the holes in the joist affected for proper pitch and distance from the above floor, leave 3” pipe on site so as the framers install the joist they can slide the pipe as each one is installed. Obviously you want as few joints as possible.
As suggested by wwhitney, after install slide the pipe in from the outside end joist may be a better option.

 

[Zimm0who0net]

Given that I'm both the plumber and the framer, I can handle that. Drilling in through the rim is a brilliant idea. (actually I'll just slide that pipe in before I install the rim).

We're trying to do as much of this ourselves. Concrete we'll hire a crew, and we'll hire out the gas, but everything else is us. Luckily we're blessed with an insanely nitpicky building inspector (who is also incredibly friendly). Probably seems odd saying that, but it's nice having someone with 20 years experience looking over your shoulder telling you how you did things wrong.

 

[FullySprinklered]

Had to do the drill-through one time. Bought a 20 foot stick of 3" and fed it through without using any couplings.

 

[WorthFlorida]

You’ll need to be careful at what location to start on the joist. The prints seems that you’re about 20’ from the washer to the drain. That is about a five inch drop from one end to the other. You’ll need to start at the toilet end so you don’t cut too high and to keep the holes as small as possible. Probably 4 inches wide minimum to allow .