Breathing vents

[marsaday]

I have a roof which doesnt have any felt and i am going to convert the attic space to a room.

My ridges need doing and so i want to know if i should add in some breather vents in place of a ridge tile.

The attic is a big draughty space at the moment, but the roof will soon only have a 25mm breathable gap under the tiles. There will still be no felting there.

If i do need to add some breathable ridge tiles, how many will be needed. The ridge is about 8m in length

 

[freddiemercurystwin]

If you have no felt the tiles should allow plenty of natural ventilation already so no need for ridge vents.