Extractor venting out of the roof - backdraft and rain

[illogitech]

Hello.

I have an extractor fan mounted on (or under.. hmm) the ceiling with venting going to a roof tile vent. I think it's been done wrong though as during heavy rain water comes in through the fan (even when it's switched off) and when it's not even particularly windy there's a nasty draft that comes into the room.

The roof has 3 venting tile things on it which were there before the bathroom was fitted, so I'm thinking they are for ventilating the roof space and they should not be used for an extractor. Would I be right?

Do I need to get a dedicated roof tile vent to pipe to? I noticed one on screwfix which has a collar that looks like it protects the fan from wind and rain. http://www.screwfix.com/p/glidevale-versa-tile-vent-grey/86667#

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[noseall]

Did the drips not stop when those two tiles were pulled back into position?

What is the pitch of the roof with the vents?

 

[illogitech]

Thank you for replying. Nope, it drips really badly in heavy rain.

The roof pitch is roughly 15 degrees or so at the point where the vents are. It's less on the lower courses of tiles.

 

[foxhole]

Very shallow pitch, I'm not a roofer but pretty sure you require a particular type of roof tile under 18 degree's, you may have tiles not up to the job.

 

[illogitech]

You're right foxhole, the tiles (Marley Modern) aren't suitable for the roof. Could that cause backdraft and dripping problems with the vent though? It's freezing in the bathroom!