Alright, maybe I’m biting off more than I can chew … but I’ve decided to do all of the plumbing install on my new house. In general, I don’t think it will be too difficult. I’ve remodeled quite a few bath’s attaching to the existing plumbing.

Anyhow, pretty sure I can handle laying out all of the hot/cold supply lines. Question I have, is that I don’t think I’ve ever totally understood the design requirements into drain vents. Basically, I’ve always just attached to the existing system without much thought into it. Now I’m faced with designing and laying out my own venting system.

Couple basic questions … are the vents there to vent odors, or to vent air pockets and avoid siphoning? How do you size vents, are they just the same size asthe drain they are venting? The plumber was talking about tying multiple vents together, into single roof vents are there guidelines to follow?

Oh well, figured I’d pick some brains here … Do you think there are some good books at the library?

Thanks, Neal

Alright, maybe I’m biting off more than I can chew … but I’ve decided to do all of the plumbing install on my new house. In general, I don’t think it will be too difficult. I’ve remodeled quite a few bath’s attaching to the existing plumbing.

Anyhow, pretty sure I can handle laying out all of the hot/cold supply lines. Question I have, is that I don’t think I’ve ever totally understood the design requirements into drain vents. Basically, I’ve always just attached to the existing system without much thought into it. Now I’m faced with designing and laying out my own venting system.

Couple basic questions … are the vents there to vent odors, or to vent air pockets and avoid siphoning? How do you size vents, are they just the same size asthe drain they are venting? The plumber was talking about tying multiple vents together, into single roof vents are there guidelines to follow?

Oh well, figured I’d pick some brains here … Do you think there are some good books at the library?

Thanks, Neal

Vents are there to allow air exchange as the water drains - both to let air in to take the place of the water and to give trapped air somewhere to go. Without one, the system wouls drain slowly, back up, and burp up through the drain into your face as you are looking down the drain trying to see why it's draining so slowly.

Vents are there to allow air exchange as the water drains - both to let air in to take the place of the water and to give trapped air somewhere to go. Without one, the system wouls drain slowly, back up, and burp up through the drain into your face as you are looking down the drain trying to see why it's draining so slowly.
Correct, and the purpose of the P trap is to hold water in the drain to prevent odors and gasses from the sewer from coming into the house.
As for sizes, there are standards by building code, check your city or counting plumbing code online or at the library. You can attach various vents from sinks and other fixtures to one vertical vent pipe if they are all located in the same area of the house, as there are distance and angle issues. Be sure to provide yourself with accessible cleanouts whenever possible to make it easier in the future to run a snake to unclog.

That all makes good sense.

I haven't asked my brother yet, but should I be setting up my rough plumbing and vents, etc before the roofers come? Should have 2nd floor walls today, then rafters by next week.

Thanks for the help again. I've been needing to make it down to the county building and check on some electric codes too.

Neal

Yes, at least the vertical vents going through the roof should be in so the roofers can properly flash them.