Under slab 3 fixture layout

[Jonas Bakkane]

Hi All, new here. I'm laying out the plumbing for my new addition. There will be a concrete slab floor. I'm struggling a little as my vent has to go in the side wall and not behind the toilet. I've uploaded a sketch I did of how I think it should be. I'd be very grateful if someone could check and see if this looks right. I'm in Snohomish county, Washington state for code.
Thanks all so much!

 

[MicEd69]

The bad news is you cannot run a dry vent horizontal until the line is 6" above the flood level of the fixture. The good news is you can GREATLY simplify your plumbing using the sink drain line as a wet vent for both the shower and the toilet.

It's hard to tell what the elevations are on your sketch, but if you have the elevation available, you can do this. Eliminate what you show as the vent line. Run the sink drain rather parallel to the vent line you just eliminated at the highest elevation to just over the shower drain line. Enter the shower drain line from above or at a 45-degree angle. Run the shower drain over to the toilet drain and enter it from above or at a 45-degree angle. The shower will be wet vented up the sink drain and then up the sink dry vent. The toilet will be wet vented up the shower drain, then up the sink drain, then up the sink dry vent. There are distance requirements between the fixtures and vent connections, so those need to be checked. The sink fitting to the vertical drain/vent line needs to be a Sanitary tee. The other connections need to be wye + 1/8 bend or combo fittings.

 

[Jonas Bakkane]

The bad news is you cannot run a dry vent horizontal until the line is 6" above the flood level of the fixture. The good news is you can GREATLY simplify your plumbing using the sink drain line as a wet vent for both the shower and the toilet.

It's hard to tell what the elevations are on your sketch, but if you have the elevation available, you can do this. Eliminate what you show as the vent line. Run the sink drain rather parallel to the vent line you just eliminated at the highest elevation to just over the shower drain line. Enter the shower drain line from above or at a 45-degree angle. Run the shower drain over to the toilet drain and enter it from above or at a 45-degree angle. The shower will be wet vented up the sink drain and then up the sink dry vent. The toilet will be wet vented up the shower drain, then up the sink drain, then up the sink dry vent. There are distance requirements between the fixtures and vent connections, so those need to be checked. The sink fitting to the vertical drain/vent line needs to be a Sanitary tee. The other connections need to be wye + 1/8 bend or combo fittings.

Ok, great info. Thank you! I guess I'll have to redraw this...
It's a small bath, so no more than 6 feet between toilet and sink.

 

[Jonas Bakkane]

Ok, great info. Thank you! I guess I'll have to redraw this...
It's a small bath, so no more than 6 feet between toilet and sink.

So like this then?

 

[GReynolds929]

Where the lav drain connects to the shower needs to be on the same plane. How you have it currently is negating any venting for the shower and toilet.

 

[MicEd69]

Where the lav drain connects to the shower needs to be on the same plane. How you have it currently is negating any venting for the shower and toilet.

I'm not I'm seeing what you are saying. Assuming all the lines are sloped 1/4" per foot towards the main 4" drain, the toilet would be wet vented through the combo entering the 3" at a 45-degree angle, then up the 2" drain line from the shower, then up the combo that is at a 90-degree from the sink, then over the horizontal sink drain line to the 90, then up the sink drain line in the wall, then up the dry vent which will vent the toilet, shower, and sink.

But you are absolutely correct that the sink and shower drain lines could be on the same plane. It's just that I prefer entering drain lines from above or at some angle rather than having everything on the same plane if the elevation allows that.

 

[Jonas Bakkane]

I'm not I'm seeing what you are saying. Assuming all the lines are sloped 1/4" per foot towards the main 4" drain, the toilet would be wet vented through the combo entering the 3" at a 45-degree angle, then up the 2" drain line from the shower, then up the combo that is at a 90-degree from the sink, then over the horizontal sink drain line to the 90, then up the sink drain line in the wall, then up the dry vent which will vent the toilet, shower, and sink.

But you are absolutely correct that the sink and shower drain lines could be on the same plane. It's just that I prefer entering drain lines from above or at some angle rather than having everything on the same plane if the elevation allows that.

Yes, I thought like you say, that when you go down the line, you connect from above. More than 45 degrees, right? Or is that just when you go from a smaller pipe into a bigger pipe?

 

[Jonas Bakkane]

Yes, I thought like you say, that when you go down the line, you connect from above. More than 45 degrees, right? Or is that just when you go from a smaller pipe into a bigger pipe?

Ok, so I'm upping the game a little. Going to 3"pipe to the split to shower and sink. Then straight line to shower and sink dropping in at 45 degrees or more. Should be good yes?

 

[MicEd69]

Looks good to me.

 

[Jonas Bakkane]

Looks good to me.

Cool, thanks for the help!