sewar gas

Hello,
I have just had a loft extension done at my house which has been signed off. i.e approved.
However depending on the wind direction i get an awful smell of fish in the loft? Most of the time there is no smell at all. However the last time it was quite severe. I have since noticed the soil stack pipe is below the level of my velux windows. Could gas be leaking in to my loft this way? If so is there anyway i can overcome this i.e fitting an external dirgo valve or something?

FISHY SMELL...

can be overheating electrical fittings. See if you have any junction boxes or light fittings that are too hot.

Could also be a loose connection, esp. in a shower switch, overheating, or a socket or immersion heater conection.

That vent should be carried above the velux ...either internaly or externaly.......NO bleeding durgo sounds like another one missed by build control/architect /builder and uncle tom cobbley.......internal then penetrating roof with lead slate would be easyer........just like on my chalet bungalow