We've just moved in to a mid 70s build house and wonder if anyone would have a suggestion or two about the following.
We noticed a breeze coming from a couple of electric sockets on an outside wall, the back of these sockets seem to be going in to the cavity. Now the house apparently has some cavity wall insulation so found this a bit surprising. I popped the cover off a nearby extremely breezy ventilation panel I had been meaning to look and found a large hole going directly outside and through the cavity, guessing this is the source of the socket breeze. I've had it suggested that it might have been because there's a gas fire installed in the room but out previous house had a gas fire and didn't have a great big hole in the wall.
On taking a picture or two in the cavity I can see some foam like insulation but it's in the distance and looks pretty degraded with nothing down low so I'm not surprised there's a breeze coming out of nearby sockets, the bits I've come across in the roof space are powdery.
Is a hole this size required for ventilation or can it be blocked? Even if so should it not be in a pipe or something?
Is this patchy insulation going to cause any problems going forward?