bathroom vent pipe?

Question

I have home that currently has two toilets, one tub, two bathroom sinks, one kitchen sink and one washing machine on the drain line that was built with the house and has proper vent pipe(s). I am adding an additional whirlpool tub and seperate standup shower in an extended bathroom. Giving the layout the contractor had to run a new drain line for these two items the length of the addition of the house which is aprox. 14 feet then have a elbow and go two more feet and join into the existing drain line. For the vent pipe on this new drain line we were told that it only has to be five foot up and at that point can be capped off and didnt need to be connected to anything else i.e. other vent pipe or out the roof as a standalone vent pipe because this drain line was for a shower and tub only. Can someone please verify this issue because I think the contractor is trying to take too many short cuts. I thought the line had to get air in to help with water going out as well as vent fumes.

Answer 1

It depends on where you live, and therefore which particular plumbing codes must be adhered to. Unfortunately, there are numerous plumbing codes, check with your local building department. It may have a name such as "Building Safety Department." Call City Hall and they will know.

Most residential buildings' drainage systems in North America are vented directly through the buildings' roofs. The DWV pipe is typically ABS or PVC DWV-rated plastic pipe equipped with a flashing to prevent water entering the buildings. Older homes may use copper, iron, lead or clay pipes, in rough order of increasing antiquity.

Under many older building codes, a vent stack, a pipe leading to the main roof vent, is required to be within a five foot radius of the draining fixture (sink, toilet, shower stall, etc.). To allow only one vent stack, and thus one roof protrusion as permitted by local building code, sub-vents may be tied together and exit a common vent stack.

A blocked vent is relatively common problem, caused by anything from leaves, to dead squirrels, to ice dams in very cold weather. Symptoms range from bubbles in the toilet bowl when it is flushed, slow drainage, and all the way to siphoned (empty) traps and sewer gases entering the building.

So, you generally cannot simply plug a vent, nor leave it unplugged but still inside your house (or attic space). To save some money, if there is an existing vent nearby, the new vent can be "T'd" into it. This would eliminate the need for a roof penetration for the new vent, saving some money.

Is this plumber licensed? Have him show you the specific wording in the code book that allows him to do what he proposes.

Answer 2

If you are unsure, talk to the building inspector on your project. But you are right and the contractor is wrong. What is the point of having any vent pipe if you cap it off? To prevent water from being sucked out of the trap for the shower or tub, each needs a vent pipe to the outside air. As another answer pointed out, the two vents can be combined into one, or they can be run back to another vent in the existing part of the house, as long as the pipe is sloped at least ¼" per foot to ensure drainage.

Answer 3

i'd get a 2nd opinion. the requirements "might be" different where you live, but here in CT, i have a flapper vent on the drain vent for my washing machine, because it can't be vented with the rest of the plumbing. that keeps the drain from getting an air lock. talk to a plumber and get his opinion, too. how much is he saving you by not running it to the existing vent system, or running a stand alone one? or, put another way, how much more would he charge for your piece of mind, to run a vent? is your vent pipe cast iron?, maybe that's why he doesn't want to hook up to it, because he'd have to cut into it up in the attic and it would be too close to the roof deck. he might not want to mess with changing the pipe going out the roof in the "old" roof section for fear of a leak. of course that doesn't explain why he won't put one in the new additions roof. you could also talk to your local building inspector, i'm assuming that he has pulled the proper permits for all of this work, and see what he says. well good luck, hope this helps.