New build waste drainage, durgos and the regs.

[jimseng]

In my new build we have installed a roof vent (lead thing that sits instead of a tile) for the waste water. As an after thought we have installed Velux windows which are less that 3 metres from the vent. The vent is a couple of tile courses above the tops of the Velux. I spoke to the BCO and he originally said "don't worry about it" but then after thinking about it a bit more he said if we can move the vent up a couple of tile courses it will probably be ok but the builder says we can't  move the vent up (I don't know why but I trust his statement). 
Some people insist we can install a Durgo in the roof space, others say there must be a vent somewhere in the system. I am trying to find out which of these is correct. 
If I have to replace the roof vent with a 900mm pipe sticking up then so be it, and I need to do it before the scaffolding comes down but I wonder what people's thoughts are. The roof would be somewhat spoiled by a vertical pipe. I don't really have an option to choose another place to put a vertical stack so my question is really just Durgo, 900mm of pipe or is there something else to consider? Everything seems rather vague. 

[Nickfromwales]

You can ask the BCO for a 1:5 or 1:10 exclusion, if you’ve got immediately neighbouring properties where you can show they all have a SVP (Soil and Vent Pipe). 
 

Then they should be agreeable to you cutting the pipe back inside the attic and fitting an AAV (Air Admittance Valve), aka Durgo, and close the roof back off.

[jimseng]

3 hours ago, Nickfromwales said:

You can ask the BCO for a 1:5 or 1:10 exclusion

I'm guessing that this isn't the case given my waste is a sewage treatment plant exclusive to my property. No mains anything here. 

[Nickfromwales]

3 hours ago, jimseng said:

I'm guessing that this isn't the case given my waste is a sewage treatment plant exclusive to my property. No mains anything here. 

You don’t need the SVP then! Just vent in the garden on a stub stack. 

[jimseng]

9 hours ago, Nickfromwales said:

You don’t need the SVP then! Just vent in the garden on a stub stack. 

Really? Is there a specific section in the regs that discusses this? (i.e. the requirements for the vent, rules etc) That would be great. So just to be clear, you are saying durgo in the loft, vent further down the line near the S.T.P?

[Russell griffiths]

 

To vent the STP you can do this with a vent pipe running up the back of a shed or into the bushes and vertical, what you don’t want is it near the patio and  bbq area. 

[Gone West]

1 hour ago, jimseng said:

Really?

We had the stub stack in the flower bed near the STP.

[jimseng]

1 hour ago, Russell griffiths said:

To vent the STP

Just to be clear, if I have a vent for the STP do I definitely not need an open vent to the house sewage system? In other words I can fit a durgo in the loft and have a vent pipe near the STP and this will cater both low pressure (durgo lets air in) and any pressure build up that would normally be dealt with by an open stack above the roof can be dealt with by a vertical vent further down in the bushes? Will the BCO accept this? (the BCO question may not be answerable, they live in a nebulous world).

[Nickfromwales]

3 hours ago, jimseng said:

Really? Is there a specific section in the regs that discusses this? (i.e. the requirements for the vent, rules etc) That would be great. So just to be clear, you are saying durgo in the loft, vent further down the line near the S.T.P?

Yup. 👍. 
 

SVP’s vent the accumulated gasses in the network sewerage system, and as you’re on an STP you don’t need to do that.

 

As above, you can put it on an external facade out of sight or just route a branch off the STP and do a short stub stack / riser in the garden or landscaping, defo away from where you’re BBQ’ing lol, although these things don’t seem to stink as much as a sewer would. 

[saveasteading]

2 hours ago, Nickfromwales said:

these things don’t seem to stink as much as a sewer would

Barely any smell but you'd not want it next to your patio just in case. I've even got one next to an ancient cess tank and even it doesn't smell. Another one serving a 3 chamber, low-tech one does whiff occasionally.

This is a different situation to needing an air intake, such as a durgo, to allow the flush to move without a vacuum holding it back.

[Nickfromwales]

8 minutes ago, saveasteading said:

Barely any smell but you'd not want it next to your patio just in case. I've even got one next to an ancient cess tank and even it doesn't smell. Another one serving a 3 chamber, low-tech one does whiff occasionally.

This is a different situation to needing an air intake, such as a durgo, to allow the flush to move without a vacuum holding it back.

Indeed. The Durgo (AAV) needs to be above any 1st floor WC, and needs to be accessible; eg if it fails and starts letting any stink out. Ground floor WC's don't need an AAV if the 'drop' (invert) is less than 1300mm.