Diameter of soil vent pipe

[andy888]

Hi,
My existing soil vent pipe is 110mm pipe and is boxed in. I have a very small upstairs toilet and want to reduce the size of the pipe. Can I do this to say 50mm or so?

thanks
andy

 

[sooey]

Can you sh*t through the eye of a needle? sorry read that wrong, if it's just the vent pipe you should be alright.

 

[andy888]

Thanks sooey,
yes at certain times I can

Are adaptors fron 110mm available?

 

[gas4you]

I've never seen one that reduces less than 3". Can they?

 

[sooey]

marley do one don't know how to post a link, I'm sure it would work but building control probably wouldn't be too happy about it, if you told them

 

[Bambergaspipe]

Hi,
My existing soil vent pipe is 110mm pipe and is boxed in. I have a very small upstairs toilet and want to reduce the size of the pipe. Can I do this to say 50mm or so?

thanks
andy

It`s 110 mm for a reason. Expect plenty of blockages.

 

[sooey]

That's the way I read it at first, but I think he is just talking about the unwetted length part. (the top bit above the bog)

 

[Bambergaspipe]

That's the way I read it at first, but I think he is just talking about the unwetted length part. (the top bit above the bog)

 

[andy888]

Bambergaspipe, thanks for the replies, dont understand why I would get blockages with a smaller diameter vent pipe?

Apart from the odours, what is the vent pipe for?

Andy

 

[Bambergaspipe]

Bambergaspipe, thanks for the replies, dont understand why I would get blockages with a smaller diameter vent pipe?

Apart from the odours, what is the vent pipe for?

Andy

I don`t think we are on the same page. I thought you wanted to reduce the toilet waste outlet to the soil stack.
The vent pipe does exactly what it says on the tin, it vents all the gases from your sewer to a point generally above your roof, thus being dispersed into the atmosphere. That`s why the sky always smells of farts. ( trust me, I asked a wood pigeon ).

 

[andy888]

Well, just bought a 68 mm pipe and 2 offset adaptors 110mm to 68mm from wickes for a tenner. The offset adaptors are ideal to put the pipe nearer the wall allowing a much smaller box.

So I'll give it a go

 

[chrishutt]

68mm pipe is rainwater pipe and can't be used for a soil vent. For one thing the joints aren't designed to be airtight, which is what you need. If the stack is internal your best option is to replace the vent pipe with an Air Admittance Valve.

 

[gas4you]

What op needs is 3" soil pipe and fittings

 

[ChrisR]

You can of course get an end-on 42 to 110mm adaptor, and since the resistance to a fart in 42mm must be 2 tenths of beggar all, I can't see why it shouldn't work absolutely fine. Secondary stacks used to be all sorts of sizes, for venting everything on a building.
I expect yours would only be a few metres long - go for it. An Air Admittance Valve doesn't let gas out, of course.

Look at the requirements for vents in the BRs, which are online.

 

[chrishutt]

Building Regulations (H1: 1.28 ) specify 75mm nominal (82mm OD) as the minimum size for a vent pipe. It doesn't really matter that AAVs don't allow outward ventilation since that will normally be provided by other soil stacks connected to the same sewer.