Second Bathroom Venting/Draining...

sootybuttercup

Adding a second floor to my house. There will be a half-bath on that level. The toilet and sink will be about 18 feet from the existing 3 inch pipe that goes vertically from the basement and up through the roof (main floor toilet and fixtures all connect to this pipe). Question is...can I simply run the toilet and sink drains horizontally and tie in where that 3" pipe passes through the new 2nd floor? If not, what venting arrangement should I have for this new bathroom? Does every toilet require a separate pipe through the roof? Thanks a ton!!

Bill

as a master plumber I can say that every trap and trapped fixture requires a vent. This can be a direct vent, wet vent, or an air admittance valve (To which unubstructed air flow can reach it) My suggestion is this
Run your 3" main horizontally to where it will tie into the existing drain, then tie in the sink with a 2" x 2" x 1-1/2" sanitary tee in the wall, (The top and bottom are 2" and the end that will connect to the sink is 1-1/2") Connect the bottom of the tee (2") into the new drain (Between the new toilet and where it will tie into the existing drain) then run the top (2") up and through the roof using a boot to install over the pipe to keep water out. As long as you tie the sink in within 10' of the toilet, this will wet vent the toilet. If you trie to just run the toilet and sink horizontally as you describe you will not have any vent for that line.
ALSO remember that you can not run the 2" pipe horizontally under the floor to tie into the 3" (Code states no vent shall run horizontal unless it is 6" above the flood rim of the highest fixture it serves) in this case would be the sink. You may use 22-1/2 degree or 45 degree fittings to achive this. So just try to lay the 3" pipe as close as possible to be under the sink, preferably so the sink can drop straight in with no bends. If this is not possible, let me know and I can work something else out for you.

__________________
Is it beer thirty yet
Virginia Department of Licensing
Virginia Plumbing Codes

sootybuttercup

Hey...thanks APB!!!! This actually makes sense (I've been reading). Rather than going through the roof again, I am wondering if it would be okay to go into the attic with the 2" vent from the sink tee...and across horizontally about 12 feet and into the existing 3" stack with a tee. The arrangement would be the same as you describe, except "no second hole in the roof". All the "horizontal" attic part of the vent would be well above the highest fixture. Once again...thanks!!

Bill

Your welcom, glad to help, just remember that the sanitary tee you use to tie into the existing stack is installed upside down.

__________________
Is it beer thirty yet
Virginia Department of Licensing
Virginia Plumbing Codes