Help with soil vent pipe height

[amin]

I’m looking for some advice on the positioning of a soil vent pipe (SVP). I’m converting my loft and adding a bathroom directly above the existing bathroom, so there is already an SVP in roughly the right location. I’m also adding a velux window on that elevation. As a result, the SVP ends up very close to the window.
 

From what I understand, that shouldn’t be an issue in principle, but it does mean the vent needs to be at least 900 mm above the window opening. I’ve attached a sketch showing the existing arrangement in blue and the proposed arrangement in red.
 

My concern is that this creates a fairly tall, exposed vertical section of pipe (around 2.5–3 m) near the pitched roof. I can lightly restrain it back to the chimney, but it still feels like an awkward solution.Does this approach work in practice and comply with regs, or is there a neater / more sensible way of dealing with this?

 

Any advice appreciated, thanks!

 

 

 

 

 

Edited Friday at 16:53 by amin

[Russell griffiths]

Cross over behind the chimney and run up the side of the dormer. 

[Nickfromwales]

Leave it close to the window, get signed off, then push a Durgo AAV into the top of the then shortened SVP, so it no longer vents. It just needs to be higher than the pan of the 2nd floor WC, by around 200mm

 

Do you have another SVP on the house elsewhere? 

 

The neighbouring properties with vents to atmosphere will be suffice for venting the network sewers, you’ll not have any negative effect from ‘capping’ the SVP with an air admittance valve. Make sure it’s an outdoor rated one though. 

[saveasteading]

2 hours ago, Nickfromwales said:

neighbouring properties with vents to atmosphere will be suffice for venting

Unless they have done the same.

[Nickfromwales]

22 minutes ago, saveasteading said:

Unless they have done the same.

I’d be happy to roll the dice, if it’s not the only 2 houses within a few hundred yards.   

[amin]

Appreciate the ideas. Going behind the chimney up dormer sounds like the easiest way to comply - will there be an issue with the number of bends required by this?

 

I won't have any other soil vent pipes, the neighbours definitely do have vent pipes. The AAV is an interesting one and would certainly look a lot better. 

 

The other thing I was thinking about was moving the vent pipe internally and going straight up to the right of the first floor toilet.

[Nickfromwales]

If it helps, the SVP can be reduced to 3” after the last WC is picked up. It’s only carrying air at that stage so capacity is no longer a factor. 
 

You can still T in a sink / bath / shower etc to the reduced SVP, it’s just solids that aren’t ideal at the smaller diameter. 
 

You can actually have a single WC feed into 3” pipe, but nobody does it.