Re: Horizontal vent pipes okay?
Posted by e-plumber on June 21, 2004 at 17:45:15:
In response to Re: Horizontal vent pipes okay?
: This is what Bob Vila has to say. Should I believe him? I could probably get 1/4" slope per foot instead of straight horizontal (it's only an 18" run if that).

: "Unlike drainpipes, vent pipes can run horizontally since gas-air pressure is drawn upward by the lower atmospheric pressure outside the house."


: Thanks!

: Mike

: : Can I have a flat section between where the takeoff starts and where it goes vertical?

: : So in other words off the takeoff install a 45 and then about an 18" flat section to another 45 heading upwards. Did that make sense?

: : If not I have other options just not as clean.

: : Thanks!

: : Mike

The vent take-off fitting from the trap arm needs to be no less than 45 degrees to the drain pipe. Then it can run horizontally, (by using a 45 degree fitting) with 1/4" pitch per foot to get it out of the floor up into the wall to make the connection.
Keep in mind that some codes require that all vent fittings and piping below the flood rim of the fixture need to be installed in drainage pattern. Check your (local) code to confirm what is required.

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