Graphic Designer Doing Plumbing Rough In - Please Weigh In...

Javelin

Plumbing Pros, I'm re-doing a master bathroom and was hoping to get everyone's feedback on my plan. Full disclosure, I put this on Reddit a while back and got some good input but a lot of smart asses, so thought it might be better here...

A few assumptions, questions, things to keep in mind.

1) Please note that all horizontal drain lines will be sloped at at least 1/8" per foot and not more than 1/4" per foot (just too hard to draw angles here)

2) I don NOT want to drill through any of the floor joists.. previous plumbing has already beaten them up pretty bad and I hope to just sister them and leave them alone.

3) I have access to the below GREEN room and am planning on putting a soffit on the one side or else otherwise lower the ceiling of what will eventually become a powder room below this bathroom.

4) The bathroom in question here is on the 2nd floor of a 3 story house. There is a bathroom above with all fixtures dumping into that 4" main stack. It's fixtures are vented with the vent from the 3rd floor bath tying into the stack right before it goes through the roof in the attic.

5) I'm planning on using 2" pipe for drain and 1.5" for vents. Toilet will be a 4" (or possible 3" if I can't fit it) tying into the 4" stack.

6) QUESTION: I was told that I can't dump the laundry washing machine into the stack above a toilet? That's why I have the secondary 2" drain line tying into stack below the toilet.

7) QUESTION: the length from the double wye between the sinks to the stack is probably about 12 feet. Is that ok to run as a 2" pipe there?

8) QUESTION: See those 3x 1.5" vent pipes going up? Can I tie them together into one 1.5" and then tie that into the 4" stack in the attic the way the 3rd floor bathroom is now?

Thank you all in advance for your expert guidance.

ethicalpaul

Those codes are so paranoid--really a washer is going to what? Suck the toilet trap dry or something?

TonKa

FWIW, this may help your problem of running pipe through joists:

https://joistrepair.com/

hot_rod

Use San tees to tie the horizontal washer and lav sinks, not a y or double y.
Are you under UPC or IPC code. Drain and vent sizing is based on fixture units.
You can find both codes online with some searching.
https://www.iccsafe.org/building-safety-journal/bsj-technical/methods-of-venting-plumbing-fixtures-and-traps-in-the-2021-international-plumbing-code-4/

psb75

Shower pan should have a 2" drain fixture, trap etc.

Kickstand55

Best to find out if your jurisdiction requires a licensed plumber.
If something goes wrong and you need insurance to cover the expense, they could deny coverage. I know of a case where this happened. Homeowner was not happy. But they saved money on the front end.

pecmsg

Javelin said:

1) Please note that all horizontal drain lines will be sloped at at least 1/8" per foot and not more than 1/4" per foot (just too hard to draw angles here)

Drains slop 1/4" per ' of run.

Is this a private residence or multi family?

Javelin

Thanks all. Pecsm - This is a private residence.

pecmsg said:

Javelin said:

1) Please note that all horizontal drain lines will be sloped at at least 1/8" per foot and not more than 1/4" per foot (just too hard to draw angles here)

Drains slop 1/4" per ' of run.

Is this a private residence or multi family?

Javelin

Thanks Hotrod, I've reworked the san tees near the washing machine and from the laundry room sink...

hot_rod said:

Use San tees to tie the horizontal washer and lav sinks, not a y or double y.
Are you under UPC or IPC code. Drain and vent sizing is based on fixture units.
You can find both codes online with some searching.
https://www.iccsafe.org/building-safety-journal/bsj-technical/methods-of-venting-plumbing-fixtures-and-traps-in-the-2021-international-plumbing-code-4/

CLamb

Which computer program(s) did you use to make those illustrations?

Alan (California Radiant) Forbes

Wonderful graphics and an excellent plumbing design.

Some answers per the UPC:

#6 Unfortunately, only the discharge of fixtures having 1 or 2 fixture units are allowed to be wet vented into a vent stack. A clothes washer carries 3 fixture units.

#7 It's OK to use 2" pipe horizontally for 2 lavs. I hope that's at least a 6" wall that you're drilling through.

#8 Combining 3 - 1½" vents into 1 - 1½" vent is allowed. Eight fixture units is the max. and you have 6.

Cleanouts aren't required above the first floor, but you could save some grief later on by installing one with a decorative cover above the double fixture fitting between the two lavs. That long horizontal run will be prone to clogging.

Are you using cast iron pipe for the drains? Noisy otherwise.

hot_rod

Alan (California Radiant) Forbes said:

Wonderful graphics and an excellent plumbing design.

Some answers per the UPC:

#6 Unfortunately, only the discharge of fixtures having 1 or 2 fixture units are allowed to be wet vented into a vent stack. A clothes washer carries 3 fixture units.

#7 It's OK to use 2" pipe horizontally for 2 lavs. I hope that's at least a 6" wall that you're drilling through.

#8 Combining 3 - 1½" vents into 1 - 1½" vent is allowed. Eight fixture units is the max. and you have 6.

Cleanouts aren't required above the first floor, but you could save some grief later on by installing one with a decorative cover above the double fixture fitting between the two lavs. That long horizontal run will be prone to clogging.

Are you using cast iron pipe for the drains? Noisy otherwise.

Good point Alan, we would use cast iron for vertical pipe that served a toilet. And have a 2X6 wall for running 3" pipe so it doesn't touch the sheetrock. Which creates a drum effect for the noise.

ChrisJ

Engineering always involves compromises.

The cons of cast iron far outweigh the pros in my opinion. If noise was a concern I'd choose insulation around PVC over cast iron any day. Now you've got a smooth lightweight drain that's quiet and not only is it smooth now but it'll be smooth 50-100 years from now.

Javelin

Javelin

Javelin said:

CLamb said:

Which computer program(s) did you use to make those illustrations?

Chrisj, I used a program called Sketchup for the mockups.. It used to be made by Google, now it's owned by a company called Trimble? If you just google "google sketchup" you'll see a link. it's a VERY powerful 3d modeling program - I use it often for developing mockups and actual renderings (using a program called Vray to get some real cool near-HGTV show quality results (see attached (patting myself on back))

Javelin

Alan (California Radiant) Forbes said:

Wonderful graphics and an excellent plumbing design.

Some answers per the UPC:

#6 Unfortunately, only the discharge of fixtures having 1 or 2 fixture units are allowed to be wet vented into a vent stack. A clothes washer carries 3 fixture units.

#7 It's OK to use 2" pipe horizontally for 2 lavs. I hope that's at least a 6" wall that you're drilling through.

#8 Combining 3 - 1½" vents into 1 - 1½" vent is allowed. Eight fixture units is the max. and you have 6.

Cleanouts aren't required above the first floor, but you could save some grief later on by installing one with a decorative cover above the double fixture fitting between the two lavs. That long horizontal run will be prone to clogging.

Are you using cast iron pipe for the drains? Noisy otherwise.

Thank you Alan for the very constructive feedback!

So for #6 - you're saying it's ok the way I have it planned out now with a separate 2" drain that then matches up into the main stack BUT has a separate dry-vent.. right?

For #7 - you say it's ok to use the 2" pipe horizontally from a drain perspective, but is the long horizontal run of about 12 feet ok there? I'm putting it in a 2x6" wall, but the wall is NOT structural - it's just for housing insulation and some electric - the house is balloon framed with meaty joists from brick wall to steel beams (another reason I'm avoiding any more cuts into those joists).

THANK YOU THANK YOU

hot_rod

ChrisJ said:

Engineering always involves compromises. The cons of cast iron far outweigh the pros in my opinion. If noise was a concern I'd choose insulation around PVC over cast iron any day. Now you've got a smooth lightweight drain that's quiet and not only is it smooth now but it'll be smooth 50-100 years from now.

A vertical cast iron stack in a residential application, dry most of the time, will outlast the wafer board shacks that are being built these days

Alan (California Radiant) Forbes

@Javelin

So for #6 - you're saying it's ok the way I have it planned out now with a separate 2" drain that then matches up into the main stack BUT has a separate dry-vent.. right?

Yes

For #7 - you say it's ok to use the 2" pipe horizontally from a drain perspective, but is the long horizontal run of about 12 feet ok there?

Yes

hot_rod

A couple other tips. Most of my plumbing was in the mountains, snow country.
When possible we would tie all the vents together in the attic or roof trusses

Then one 4” vent thru roof VTR. Also go out near the top pitch of the roof. The VTR needs to equal the drain pipe leaving the building. Same pipe area calculation. In some cases 3” was okay.

This took care of any snow shear, less roof penetrations, and a cleaner look. Keep the penetration on the back side of the roof when possible.

Roofers loved it, especially the metal roof jobs.

Every spring we fixed snapped off roof vents on homes that the warm climate plumbers piped. Kitchen vents at the bottom of the roof pitch took the worse hit.

All the pipe sizing, vents and drains goes by FU fixture units. Same for acceptable lengths. It’s all in the tables available online.
Determine if you are under IPC or UPC codes. Or any codes at all!

The biggest mistake DIYers make is not venting properly. Then you deal with dry traps and sewer gas forever.

Alan (California Radiant) Forbes

As long as we're reminiscing, the city of San Francisco requires at least one full-bore vent stack unlike other jurisdictions that allow you to add up smaller vents to equal the area of your building drain.

That makes sense, but once, I stubbed up a 4" drain in the garage of a 4 story house - because I wanted a large cleanout - and then reduce to 3" for the run up to the toilet, but the inspector said that I couldn't reduce the size once I stubbed up.

And SF requires a totally separate rainwater system with traps and vents on decks and roofs close to windows or doors; all cast iron and copper on most houses. Yes, totally separate from the sanitary system until they combine at the sidewalk. So, the city has to treat storm water as well as sewage.

It all gets very expensive.

hot_rod

Alan (California Radiant) Forbes said:

As long as we're reminiscing, the city of San Francisco requires at least one full-bore vent stack unlike other jurisdictions that allow you to add up smaller vents to equal the area of your building drain.

That makes sense, but once, I stubbed up a 4" drain in the garage of a 4 story house - because I wanted a large cleanout - and then reduce to 3" for the run up to the toilet, but the inspector said that I couldn't reduce the size once I stubbed up.

And SF requires a totally separate rainwater system with traps and vents on decks and roofs close to windows or doors; all cast iron and copper on most houses. Yes, totally separate from the sanitary system until they combine at the sidewalk. So, the city has to treat storm water as well as sewage.

It all gets very expensive.

I always put a test T where the sewer line entered the building. So it served as the place to put the test plug, and it was accepted as a two direction cleanout.
I don't think that inspector made the correct call. Unless the local AHJ had an addendum addressing size reduction?