I've searched the forums and read the ones discussing air vents/bricks, and also looked in the projects page to understand the 'lie of the land' before posting.
I'm bricking up an unused fireplace in a house about 30 years old. It had an open flame gas fire in it previously (with a nasty brick fireplace!). It's worth noting that although the chimney stack was originally outside, there has subsequently been an extension built on the far side, so the stack is now internal for most of the way up until about 2/3rd of the way up the second storey.
I've got two quick questions:
a) Do I still need an air vent where the fireplace used to be, for airflow, if the chimney is now internal?
b) If I need to have an airbrick/vent, how do I know what size?
Thanks in advance!