DWV Layout Assistance

[robh]

Hi folks.

I have a bathroom remodel project and some rather difficult venting constraints ( two outside walls, shallow ceiling, two tiered floor framing etc ). I made a stab at the venting ( see below ) although I suspect the wet venting of the tub and shower might not be up to code ( Seattle, WA ). The diagrams are color coded for pipe size - Red=3", Green=1.5", Blue=2".

http://lh5.ggpht.com/rhubley/SGM9V4zOPiI/AAAAAAAAAL8/upYU72qYqg4/vent1.JPG?imgmax=800
http://lh6.ggpht.com/rhubley/SGM9WCcKgVI/AAAAAAAAAME/CPFnEsHT7zI/vent2.JPG?imgmax=800
http://lh3.ggpht.com/rhubley/SGM9WbEiM-I/AAAAAAAAAMM/J0o_5g5tQAc/vent3.JPG?imgmax=800
http://lh5.ggpht.com/rhubley/SGM9WrtHO2I/AAAAAAAAAMU/E6JEusPPehA/vent4.JPG?imgmax=800

I would appreciate any pointers or suggestions.

-R

[robh]

No feedback? It must be the most amazing layout anyone has ever encountered or it's the worst. :-)

[sjsmithjr]

I'm not a professional plumber, but:

I think the way you've tied in the washing machine drain will give you troubles.

It would appear to me that your premonition was correct about the tub and shower venting - that's not going to work.

I'm sure one of the pros will be along shortly.

[mnalep]

I can't comment on the correctness, but I do wonder what software you used to create this?

[Redwood]

Okay...
The tub is not vented with the elbows running down to the drain before hitting the vent you have made an S-Trap.
The shower is not vented.
Putting the washer on the toilet has created a venting issue there as well.
Are those wye's or, sai-tee's bringing in the tub, lav, and shower to the red line?

Nice drawing by the way!

[hj]

The shower is not vented, and depending on how you actually install the tub trap, it could also have a problem. The washer into the toilet vent could create a problem, I have seen situations where draining the washer aspirated the water out of the toilet bowl.

[robh]

mnalep: I used Google's Sketchup program. It's fantastic for conceptualizing projects.
Redwood: I used wye's on the mainline drain.

Thanks for the feedback. Here is my problem with adding vents to the tub/shower. The walls closest to the tub and shower are outside walls ( left of tub and parallel to the final red pipe run ).
So I can't vent out those walls. Also my ceiling is very very shallow ( above the shower it's a 3" ceiling ). Would you recommend attempting to run a vent up the outside wall across the
ceiling and connect to the toilet or the sink vent? Where would you bring the washer drain into this system if not in the toilet vent stack?

Thanks again,

-R

[Redwood]

The washer could drain into the line below the toilet and revent into the toilet vent. The bathtub you show the line curving up and then back down to the drain. If it went in straight without the downward curve it would be vented by what you show. You can run a vent in the outside wall to the attic and tie in above.

[robh]

Redwood: Thanks for the quick reply. I will re-route the washer and fix that problem. The reason for the curve up in the bathtub line was to accomodate the trap. Are you suggesting I remove the trap?

I will redraw my plan and see if it matches the comments.

Thanks everyone.

-R

[Redwood]

No, you need a trap but if you had a longer tailpiece out of the tub and into the trap then the drain could go straight into the drain, The curve creates an S-Trap effect and makes it unvented.

[construct30]

The bottom of the pipe where the P-trap starts to drain cannot be higher than the top of the pipe where it goes into the main drain, it does what they said and turns it into an S-trap. That is why there is a limit on the length of an unvented pipe from the vented stack with proper fall.

[mnalep]

Robh, Thanks. I will download google SketchUp and try.

Did you do your drawing with the free version?

Did you have to draw the individual items in your layout (tub, sinks, pipes, toilets, etc), or was there a library of these things you started building your diagram with?

[robh]

Redwood/Construct30: Thanks for the advice. Now I understand the problem. If I lower the trap to the same level as the red pipe ( pipe vertically down from tub ) and then run a connection over to it with a gradual slope it will be ok.

mnalep: You can use the free version although printing is a bit restricted. Also I don't know that you can import/export to autocad format in the free version. The sink, tub, toilet, and vanity are all standard objects that come with sketchup. I made the pipe...and the fittings are imported autocad drawings supplied from Thomas Net and the fitting manufacturer.

[robh]

Here are my updates. Is this closer?

http://picasaweb.google.com/rhubley/DWVDiagram/photo?authkey=k2P7vHhhN5A#5224244719951502578

http://picasaweb.google.com/rhubley/DWVDiagram/photo?authkey=k2P7vHhhN5A#5224244723469461586

http://picasaweb.google.com/rhubley/DWVDiagram/photo?authkey=k2P7vHhhN5A#5224244726447684322

[Redwood]

Your shower is now vented on the wrong side of the trap.
The shower vent also has to go ino the vent higher to prevent the washer from flooding the vent.

[hj]

Conventional practice would tie the shower vent into the horizontal section of the washer drain where it connects to the toilet vent riser. The shower vent connects AFTER the "P" trap.

[robh]

Oh...I can't believe I placed that above the p-trap. My only excuse is that it was late at night when I was working on these drawings. I will tie the shower vent into the horizontal section of the washer vent. Also I will connect the vent after the trap and upload the drawings. Thanks so much for the help. You guys are great!

mnalep: Here is a link to the CAD drawings of common DWV PVC fittings:
http://www.thomasnet.com/cadlibrary.html?cov=NA&which=cad&what=Fittings%3A+Pipe%2C+PVC&pdtl=A&heading=95928016&searchpos=1&cid=10016195&az=26487751&navsec=results

[robh]

Ok...here are the changes. Look ok?

http://picasaweb.google.com/rhubley/DWVDiagram/photo?authkey=k2P7vHhhN5A#5224602973979878162

http://picasaweb.google.com/rhubley/DWVDiagram/photo?authkey=k2P7vHhhN5A#5224602972234287074

[Redwood]

Much much better than before!

[Mikey]

Why did the washer drain go from 2" to 1 1/2"? I'm not sure that's legal...

[robh]

Mikey: Do I need 2" for the waste section or do I just need to extend the 2" vent pipe down to the sanitary T?

[Mikey]

I think the standpipe and waste line need to be 2", but wait for a real plumber to cite chapter & verse. Modern washers throw an awful lot of water out the drain in a big hurry.

[Redwood]

Good catch Mikey! I missed that change...
The washer standpipe, p-trap, & drain need to be 2"
The vent can be 1 1/2"

[robh]

Thanks for the advice on the washer pipe. I decided to stick with 2" for the vent portion since I am tying it into the 2" toilet vent. I also moved the shower vent over a couple of joists to make room for the washer p-trap. Lastly I tied the vanity drain vent to the main stack to save on a roof penetration. Any last bit of advice on this layout? Thanks so much for the feedback.

[Mikey]

Clothes washer drain still labelled as 1 1/2", but colored as 2". It also looks kind of high -- check local regs to see how high/long the standpipe needs to be.

[hj]

It looks like it happened when he relabled the size.

[Redwood]

As far as the actual size and basic design it looks good. Now if the actual nuts & bolts get put together right...
This would include the details like pitch, trap height and standpipe length...

[robh]

Ok...so I looked up code on the standpipe for the washer and it looks like 18-30" is ok. So I made it 30" above the P-trap. I also corrected the labels for the washer ( it is 2" ). I assume that the shower vent and the drain pipes should have a 1/4" per foot pitch.

[Redwood]

The top of the washer standpipe also needs to be above the top of the washer so that the water will not drain by gravity. With washers most do not have a valve on the discharge so if the drain hose goes below the water level in the washer it will drain by gravity.

[robh]

Ok...I think that's it. Thanks to all who commented. If I can help with sketchup or anything else computer related let me know.

Cheers,

-R

[Redwood]

We do require in process and after pictures for our advice you know... LOL

[robh]

That's like asking to see baby pictures -- be careful what you ask for. :-)

[Redwood]

We maintain in process quality control and pat you on the back when you're done.:cool: