We have a WC in a bathroom in a rear single storey extension, which also has a kitchen.
The soil pipe for the WC is vertical into the bathroom floor and drains into the underground sewer chamber next to the property (which I beleive is about 2m below ground). The WC is against an external wall to the side alley where the manhole for the sewer is.
I believe the kitchen sink waste connects to the same sewer chamber (or possibly to the WC discharge pipe).
My builder has put in a new ventilation pipe (VP) which comes out of the ground in the shared alley and runs up the extension wall and bends over side door to connect to the VP attached to the main house (latter pipe is also the pipe used to discharge waste from house WC)
This new VP is very unsightly and i'm thinking what options there may be to remove it and do something else instead.
I believe the new VP cannot be shortened and capped with an air admittance valve, as latter cannot be used externally?
Could WC soil pipe be taken horizontally through wall instead and connected to this ventilation pipe (which I suppose would then become a discharge pipe) - my reading of the regulations is this may be OK if the slope is low enough. However, this would mean the kichen waste loses ventilation?
Any help much appreciated