venting 2nd floor bath

**bwc** · 12-02-2012, 07:32 AM

I am adding a new bathroom on the second floor. Can I tap into the vent from the first floor bath in the attic so to save from putting another vent through the roof? The horozontal distance is about 15'. If so, can I do it with 1 1/2" pipe (ABS)?

**jimbo** · 12-02-2012, 09:59 AM

You can tap your 2nd floor vent into that. You can NOT put any WASTE into that vent line from the first floor. Your second floor vents cannot be horizontal ( less than 45 degrees) until 42" above the floor, and must ALWAYS have some minimum continuous slope back towards the drain, to avoid bellies which would fill up with rain water

**Hammerlane** · 12-02-2012, 10:05 AM

see if this helps, what size is the vent going thru the roof? 3"?

**bwc** · 12-02-2012, 03:26 PM

Thanks. That is helpfull

**cacher_chick** · 12-02-2012, 05:11 PM

If you are running a new vent through the roof you will also want to look at your local code. Many places will not allow a vent smaller than 3 or 4" to penetrate the roof due to the possibility of frost closure during the winter.

**SacCity** · 12-02-2012, 06:22 PM

If you are going to have a toilet in the bathroom, min vent size is 2 inch

**Tom Sawyer** · 12-03-2012, 04:57 AM

Originally Posted by SacCity

If you are going to have a toilet in the bathroom, min vent size is 2 inch

Only if he's under the UPC. Under IPC it can be 1-1/2 and it doesn't even have to be in the same location as the WC

hj · 12-03-2012, 06:35 AM

quote; Under IPC it can be 1-1/2 and it doesn't even have to be in the same location as the WC

THe IPC would probably allow it to be in the house next door, if that was the cheapest way to install it.