Hi everyone,
Need help with something called a "stack vent" or "stack vent pipe". In my 20-year-old, single-storey terrace house, it's a big ass pipe that comes up from the bathroom floor and goes up into the roof. I'm redoing the bathroom and the (young!) contractor says I don't need that pipe, it's old fashioned, we can get rid of it. But Google seems to say it's important! For venting gasses from the connected sewage system, as far as I can gather. Any experts who can advice me, please?

Many thanks in advance!

SuziQ

How big is the pipe? Usually vent pipe is small in diameter.

Hi there, i am a M&E consultant, vent pipe is necessary to vent out smells from water closet and floor traps (and manhole if applicable).

We are still using it for sanitary plumbing design (e.g landed property or high rise) hence from what i can tell, your contractor did not know what he is doing. The white cowl at every unit roof top is visible (normally above toilet room), you should be able to know if it is outdated

You need to have 50mm UPVC horizontal vent pipe connecting floors trap and water closet and then linked to a 75mm UPVC riser. The riser will go to the rooftop at 900mm height above roof level c/w UPVC vent cowl.

That's all.

This post has been edited by Edward Winter: Apr 16 2015, 11:07 AM

If you don't have it some of your toilets won't be able to flush properly. It helps maintain a neutral air pressure so that your waste can flow to the sewage/septic tank by gravity.

wow ! we have some very good technical experts here. salute to you guys !

75mm diameter Vertical vent pipe needed in single story house?

As long as you shit in your home, you need it.

Haha. I need to rephrase my question.
Such a big diameter (75mm) vertical vent pipe is required in a single story house?

Actually 75mm is not just a vent pipe. It is a sewage pipe. It is straight connect to your main hole and many branch out to toilet and sink.

I thought vent pipe and sewerage pipe is separate pipe, nope?

Nope. It is actual the sewage pipe. Very easily see. Check your vertical pipe in the toilet where it go up. Than go outside and see the roof vent pipe location.

Now that i know it is single storey. my bad .

Yes it is seperate pipe. Normally soil (WC) and waste (floor trap, sinks, kitchen) combined in one pipe (Soil and Waste Pipe) while vent pipe is another pipe. Soil and Waste pipe should be 150mm (no matter is single or double) to avoid choke up in the pipe (e.g. sanitary pad...). Vent pipe varies because there is no fluid running inside so i would suggest 50mm for single and 75mm for double.

In OP case, the vent pipe should be connected directly from manhole and rise to roof top. No connection needed for WC and floor trap.

Soil and waste pipe is same, vent pipe is a separate pipe.

Ok, understand now. Thanks

It also depend, if you have few of this vent pipe, you dont need to be 75mm, 50mm or less is ok. I have one in front for my master bedroom toilet, is small, maybe 1+", and the back is 2".

And yes is a must to have, if not you hear lots of blub blub sound when flush

Ya, my house one i think is 25mm only.

Soil and waste pipe is from the kitchen (sink and floor trap). That is direct to Main hole and no vent. It is correct.

Bathroom sink, floor trap and wc is to sewage pipe 75mm. The vertical sewage pipe go down is to main hole and up to roof is to vent.

This is from what I explore in my home. Include checking inside the main hole.

Wah! U open manhole to check ah.

Sure lah. New house don't have anything 1. And it fascinated me to see inside.

But warn you. Don't simply open it, if many many yrs. Bad experience for me.

what happen when u open it ?

I once open a man hole at my working place. Fark, hundred of hundred of bugs craw out from the man hole and run everywhere. Just like you see those movie.

Sheltox and burner finish up also can't kill them all.

I know what you mean, hehe.

Wow, so many thoughtful replies! Thanks, everyone. I'll post some pics (if I ever figure out how to do that -- old-age newbie here) in case anyone's interested. And now I'm VERY worried about my contractor!!!! If he doesn't know this is necessary, what else does he NOT know???!!! Aiyoh. And too late to change. Sigh. Wish me luck with my renovation, please, folks, looks like I'm gonna need a lot of it....

Do your own study and assist him ba.