Hi gang , newbie here. I have an old style stink pipe outlet that is 110mm ?? ,my question is can i reduce the size half way up to say..something like guttering pipe as there is no clearance from the outlet pipe and it will not physically fit up the wall. A smaller pipe would just about do it with a home made connection) (i am not going into the guttering i just want to know whether i can use the pipe as soil pipe venting only) Oh ,i need to get this signed off by the building inspector so need an answer thats legal and not just something i could get away with. Cheers everybody.
the smallest size you can use on a main vent pipe is 75mm, I'm not sure you can use rainwater pipe for this purpose, I've never altered the size from 110mm, if i remember rightly the pipe has to be at least 300mm above the gutter line.
On a new build I was on once we reduced the size of the vent to 50mm to get it into the attic an vented throu tile vents, it was ok'd by the BCO,
Could they install a Air admittance valve? The stack needs to vent 900mm above a wi dow opening within 3 meters. But i have seen many which are not.
Thanks Tom and I'm afraid I am doing the work myself as the builders are not interested in correcting their mistake so I do not know what an air admittance valve is. Cheers.
An AAV prevents foul smell emanating, but admits air into the stack. They are limited in use to dwellings of no more then 3 storeys, in upto 4 adjacent buildings so long as the fifth stack terminates conventionally. They are terminated inside a building. Or as Phil has mentioned the stack can reduce to 75mm min. if its serving a WC or; 'the internal dia. of the stack should not be less than that of the largest trap or branch discharge pipe'. Screwfix sell 'internal' and 'external' AAVs http://www.floplast.co.uk/products/soil-and-waste-systems/air-admittance-valves
82mm (3"/75mmID) is the smallest you can fit to meet the building regs. As for height its 900mm normally above a window.