Bathroom Reno DWV Routing Opinions

[void]

Hey all, I've been lurking the forum for a while, I find all the info here quite useful!
I decided to post a plan I've been working on for an upcoming project, to get some opinions.

I will be renovating a main floor bathroom (10' x 11'-6") into two separate bathrooms, I'm confident I can do this myself but I may call in a pro if things get hairy.

I can't salvage any of the existing fixture locations.
My tie point will be a 3" pipe that currently runs under the room for an existing toilet, shower, tub and sink. The existing toilet is currently located across from where the 48" vanity will go.

The model is my best interpretation of how I think the DWV should be routed.
The closet flanges are spaced minimum 15" from center to either side wall, and 12" from center to the back wall.
All piping and fittings shown are 1-1/2" except for the 3" runs from toilets.

My basement has a finished ceiling, so I'm not 100% certain on these joist locations and existing pipe locations yet.
I'm trying to keep all the piping as high up as possible between the joists. Joists are 9" solid lumber spaced 16".
I've noticed those 3" combos need a lot of head space with the 3" san tees above.
Nothing is shown with a slope, but assume everything is sloped properly.

 

[wwhitney]

A few initial comments:

To split a 10' x 11'-6" room with a wall to make 2 bathrooms, wouldn't it be nicer to split the 11'-6" dimension in half, to get two rooms with a lower aspect ratio?

The lower 3" horizontal line is presumably below the joists, do you plan a soffit or bulkhead for it? Showing which part if any of the DWV depicted is currently existing would be helpful.

The lav trap arms, vents, and possibly the tub trap arm are fine at 1-1/2", but the rest of the smaller pipes should be (or at least would perform better as) 2".

Right now the only wet venting you have is for the tub at the end. If you prefer to reduce dry vents, you could reduce the number possibly as low as 2 by using wet venting. Although that would require drilling some joists for 1-1/2" or 2" drain lines; it's nice that your current layout doesn't require that at all.

Just to confirm, the 12" measurement on a WC location is to the finish wall surface behind the tank. And if there's a baseboard below that projects out more than that, you need to confirm the additional clearance on your model of WC.

Cheers, Wayne

 

[Sponsor]

 

[void]

A few initial comments:

To split a 10' x 11'-6" room with a wall to make 2 bathrooms, wouldn't it be nicer to split the 11'-6" dimension in half, to get two rooms with a lower aspect ratio?

The lower 3" horizontal line is presumably below the joists, do you plan a soffit or bulkhead for it? Showing which part if any of the DWV depicted is currently existing would be helpful.

The lav trap arms, vents, and possibly the tub trap arm are fine at 1-1/2", but the rest of the smaller pipes should be (or at least would perform better as) 2".

Right now the only wet venting you have is for the tub at the end. If you prefer to reduce dry vents, you could reduce the number possibly as low as 2 by using wet venting. Although that would require drilling some joists for 1-1/2" or 2" drain lines; it's nice that your current layout doesn't require that at all.

Just to confirm, the 12" measurement on a WC location is to the finish wall surface behind the tank. And if there's a baseboard below that projects out more than that, you need to confirm the additional clearance on your model of WC.

Cheers, Wayne

Thanks for your input Wayne!

I too would have preferred splitting the longer dimension, however there's a large window on the exterior wall, so I'm mostly trying not to fuss with that and the brickwork. Although it would be nice for both rooms to have a window.
The existing room's door and window locations make it easier for me to just split the 10' dimension. This was originally a bedroom that the previous owner converted into a 4 piece when their kitchen reno took over the original washroom.

The existing lower 3" horizontal line is in a bulkhead and then turns into the furnace room, to the north. I'll have to do some measuring to add it to the model correctly, along with the joists and then I'll post an update.

Noted on the 2" for the other drains, I'll be sure to make those the correct size.

Noted on the wet vents, I was trying to avoid cutting larger holes into the joists because I can't confirm their condition with the drywall basement ceiling. This room is roughly above the middle of the joists.

Okay, noted on that 12"measurement for behind the toilet. I'll make sure the flange location requirements accounts for the final finished surfaces like baseboards, tiles or cabinets.

 

[wwhitney]

Yes, the window is clearly a constraint if you don't want to modify it. So, looks good given the constraints, and running the extra vents to avoid drilling joists is a reasonable tradeoff.

One option in case it is helpful for you: where you have a horizontal drain jogging down and connecting to the lower 3" horizontal drain, you are showing a quarter bend or san-tee going into an upright combo. That works, but when the two horizontal drains are perpendicular to each other in plan view, you also could roll the quarter bend or san-tee 45 degrees about the horizontal inlet, and then use a wye instead of a combo. That might be useful for the WC(s) as it would be a shorter (although wider) configuration.

Cheers, Wayne

 

[void]

Yes, the window is clearly a constraint if you don't want to modify it. So, looks good given the constraints, and running the extra vents to avoid drilling joists is a reasonable tradeoff.

One option in case it is helpful for you: where you have a horizontal drain jogging down and connecting to the lower 3" horizontal drain, you are showing a quarter bend or san-tee going into an upright combo. That works, but when the two horizontal drains are perpendicular to each other in plan view, you also could roll the quarter bend or san-tee 45 degrees about the horizontal inlet, and then use a wye instead of a combo. That might be useful for the WC(s) as it would be a shorter (although wider) configuration.

Cheers, Wayne

Right, thanks Wayne. I think I get the general idea idea of what you're talking about.

For instance, the original is a 3" combo on the lower horizontal connected to a 3" san street tee on the upper perpendicular horizontal.

I could save some height with a 3" wye on the lower horizontal to a rolled 3" san tee on the upper perpendicular horizontal. This would also allow me to offset the vent from the lower horizontal if it's not running where I have assumed.

Would you suggest clean-outs anywhere?
- Nick

 

[wwhitney]

I'm not so knowledgeable about cleanout locations. I suggest consulting your plumbing code.

In your last rendering, the vent offset can't be horizontal, as the dry vent needs to be at least 45 degrees above horizontal until at least 6" above the fixture flood rim.

But you could use a 60 degree bend in the san-tee inlet to turn to rising at at a 45 parallel to the joists. And then a 45 to turn up.

Cheers, Wayne

 

[void]

Great thanks, I didn't consider that for the vent. I get why vents should be normally vertical to above the flood rim now.