Chimney removal - does the flue need to be vented top and bottom?

[Rollerball]

I'm soon planning to remove a brick chimney that is connected to an unused fireplace in my bungalow.

Once the chimney stack has been reduced to the roof line do I need to install something like a vent tile where it was removed so that the flue has some airflow? Or can it just be left 'open' with only roof felt, a batten or two and tiles above it?

There is a small plastic sliding vent in the room where the fireplace was removed and covered over many years ago.

 

[Bonni]

The air in an unvented chimney stack condenses, this can cause damp. To avoid this in a blocked off/redundant fire, you fit a 9"x9" vent at the base and a vent cowl on the top (or some kind of mesh etc..)

There's a thread somewhere asking about what happens if the chimney stack was taken down below tile level.

Not all closed stacks causes damp, but that's why stacks are vented after disuse.

 

[Rollerball]

Thanks for the advice.