Tips/tricks for vents in attic?

[pghsebring]

Never had to combine vents in attic before. Always went straight out roof with one stack. Now i have 3 vents going up 3 walls i need to combine in attic. Any tricks to this? Is it as straight forward as it seems? Flip a sanitee over, make sure there's 1/4" pitch on the horizontal? Since i have 2 lines that need to come to the third one that goes out roof, how high above the joists would you put the first horizontal? A couple inches or a foot? I've never seen this done in person, just in books, that's why i'm asking. Anything i need to watch out for?

Thanks in advance.

[Terry]

The vents can rest on the framing.

[Tom Sawyer]

Yea, they need to pitch back towards the drain(s) but not necessarily a quarter inch per foot. Just enough to make them drain. Most guys use upside down plastic J hangers. I like to use strips of 3/4 plywood with holes drilled in them.

[Gary in NJ]

Also, the three vents do not need to connect at the same location.

[LLigetfa]

Use lots of supports as the pipe can sag from the heat. I watched an episode of "Ask This Old House" recently where Richard had to redo a horizontal vent in an attic that had a sag which completely filled with water.

[hj]

It is pretty much, "do it however it works best for you". There are few "regulations" regarding vents as long as they do NOT turn downward before connection together.