Ask Me Help Desk - Critical Distances and Venting

Hello,

I'm planning on remodeling the bathrooms in a two story house. The house currently has cast iron and galvanized lines. Some of the fixtures will be moved and instead of working with the cast iron, I plan on replacing everything with PVC. The bathrooms are stacked one above the other and share a single stack/vent pipe. The rooms are 8 feet wide and the stack/vent pipe is centered on the wet wall, so the farthest possible distance from it is is 4 feet. I plan on using 3" pipe for the stack/vent and 2" pipe for the rest of the drains. My qustion is this: since none of the drains will be more tha 4 feet from the vent, and if I'm reading the charts correctly the critical distance for 2" drains is 5 feet, do I really need separate vents for the fixtures or will the 3" stack/vent handle it all without any further plumbing? I was ready to put in vents on all of the fixtures until I ran into the critical distance information. I figure why make it more complicated than it needs to be, but it sounds too easy and I'm probably missing something so I thought I'd run it by the experts.

Thanks for you time.
Tim

Hey hey... Tell me, do you have only 1 waste stack picking up two bathrooms one right above the other? If so then this is a waste stack and you must tie the vents for the first floor bathroom together and run that vent pipe(2") up into the second floor bathroom at least 6" above the finished height of the lavatory before tying into the vent stack on that floor.. OR run the 1st floor vent pipe into the attic and connect into vent up there.. whichever is more convenient.

You were headed in right direction earlier... you will need to individually vent all fixtures unless can wet vent the toilet or tub/shower. Here, if possible, connect a 3x2 wye (roll above center line of toilet waste line using 22.5 fitting to make it a valid vent) just prior to toilet elbow and run that to the lavatory full 2" size...stub out 1.5 inch for lavatory and continue vent 2" all the way to vent tie in on next floor up or at attic (you will then connect the tub/shower vent in at this 2" pipe (on 1st floor now) six inches higher then the finished height of the lavatory sink rim). Or can reverse this and wet vent the shower....just pick up lavatory same way....and again roll that 2"wye just prior to p-trap and then pickup lavatory.

I hope this helped... a little confusing? If so just ask away we are glad to clarify if needed! If this answer helped please RATE THE ANSWER below. Thank you!

Quote:

Originally Posted by HDFLSTNI

Hello,

I'm planning on remodeling the bathrooms in a two story house. The house currently has cast iron and galvanized lines. Some of the fixtures will be moved and instead of working with the cast iron, I plan on replacing everything with PVC. The bathrooms are stacked one above the other and share a single stack/vent pipe. The rooms are 8 feet wide and the stack/vent pipe is centered on the wet wall, so tthe farthest possible distance from it is is 4 feet. I plan on using 3" pipe for the stack/vent and 2" pipe for the rest of the drains. My qustion is this: since none of the drains will be more tha 4 feet from the vent, and if I'm reading the charts correctly the critical distance for 2" drains is 5 feet, do I really need separate vents for the fixtures or will the 3" stack/vent handle it all without any further plumbing? I was ready to put in vents on all of the fixtures until I ran into the critical distance information. I figure why make it more complicated than it needs to be, but it sounds too easy and I'm probably missing something so I thought I'd run it by the experts.

Thanks for you time.
Tim

Nice try Tim! EVERY FIXTURE that has a trap MUST be vented. You may not wash a vented fixture past a unvented one.
It depends on which code you're working under as to the distance between trap and vent. For a 2" trap under Uniform Plumbing Code the distance is 5'. While under Standard and International Plumbing Code it's 6'.
Most bathroom groups are roughed in like this.
Toilet connects to sewer main or the stack vent. Lavatory connects to toilet drain and runs a vent off the top the stubout tee out the roof or revents back into a dry vent in the attic.. The toilet wet vents through the lavatory vent and the tub/shower connects to the lavatory drain and is wet vented by it. The vent off the lavatory may be run out the roof or revented back into a dry vent in the attic or if you're reventing back into a fixtures dry vent you must make your connection at least 6 inches over that fixtures flood rim. This is a normal rough in and is acceptable both by local and state codes and also The Standard Plumbing Code Book in 90 percent of the country. Check your local codes.to make sure you're not in the excluded 10 percent. You may revent the lavatory vent back to a dry vent or tie back to a roof vent in the attic. Good luck, Tom

Quote:

Originally Posted by HDFLSTNI

Hello,

I'm planning on remodeling the bathrooms in a two story house. The house currently has cast iron and galvanized lines. Some of the fixtures will be moved and instead of working with the cast iron, I plan on replacing everything with PVC. The bathrooms are stacked one above the other and share a single stack/vent pipe. The rooms are 8 feet wide and the stack/vent pipe is centered on the wet wall, so tthe farthest possible distance from it is is 4 feet. I plan on using 3" pipe for the stack/vent and 2" pipe for the rest of the drains. My qustion is this: since none of the drains will be more tha 4 feet from the vent, and if I'm reading the charts correctly the critical distance for 2" drains is 5 feet, do I really need separate vents for the fixtures or will the 3" stack/vent handle it all without any further plumbing? I was ready to put in vents on all of the fixtures until I ran into the critical distance information. I figure why make it more complicated than it needs to be, but it sounds too easy and I'm probably missing something so I thought I'd run it by the experts.

Thanks for you time.
Tim

Thanks to both massplumber2008 and speedball1 for the quick and insightfull answers. You didn't save me any work, but you'll be keeping the waste flowing downhill and out of the house and that's what's really important! So it's back to the original plan... vent EVERYTHING! Have a good day guys and again thanks for all your help (I knew it sounded too easy).