How to fit an air admittance or Durgo Valve

Air Admittance or Durgo valves save making more holes in the roof to vent the toilet gasses from new bathrooms and en suites. Fitting an air admittance valve on top of a new soil and vent pipe is not hard and this video explains exactly why you do it and how. For more information, see our project here: https://www.diydoctor.org.uk/projects/air_admittance_valves.htm