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.