can I block up a cavity wall vent?

[Iotrez]

Hi all,
I am renovating a 1950's ex local authority house and in 3 of the upstairs rooms there are large air vents high on the wall (the vent covers are designed in a wedge shape that points upwards). I have opened one up and it doesn't lead to the outside, it's just a hole that opens up into the cavity wall. I have never seen this type of vent before, is it important or can I block it up? If I can block it up, then what is the best way to do it?

Any help would be apreciated as my girlfriend is driving me mad worrying about spiders!!!!

Thanks

 

[noseall]

do you wish to open this vent up to the outside in the future?

unless this hole in the wall ultimately vents to the outside then i can't se what purpose it serves.

 

[Iotrez]

Thanks for your reply.

2nd look and there is brick grill on the other side of the cavity (although its not visible externally), so I am assuming that this does go to the outside.

This particular vent is in the bathroom and I was planning to put an extractor fan in but is there any need if I keep this vent?

 

[loafer]

is there a gas appliance in the room??? check with regs re gas fires. gas vents are not clossble and should be left open and not obstructed... if the pressure in the flue... that is chimney breast is iffy or the chimney has not been lined then it may be dangerous to close up.... carboin monoxide and all...

if no gas appliance or if balanced flu then close up and get riddo the draught

 

[JohnD]

Maybe the outside air brick has been rendered over? It could be a handy place to put your extractor and save you coring out a new hole.

Or poke the outside clear and fit a hit and miss vent to keep the vampires out. You can open it on curry nights.