Air gap in chimney exterior wall ?

[David King]

Hi all,

My first post in IN. I came across this air gap in a chimney face, just under the chimney cap. Gap was clean and rectangular; looked like it was built this way. There is a flue/liner in the chimney for exhausting the gas water heater.
Can I assume that this air gap is normal and used for some form of chimney venting ?

Thanks / Dave

[Raymond Wand]

I have not seen anything like that ever in a masonry chimney. So I would say it is not normal.

[Eric Barker]

If I'm looking at what I think I am, it should not be there. That's enough reason to have it checked out to be sure.

[David King]

Raymond / Eric,

Thanks for your reply. I had already reported "further investigation required".....just wanted to be sure that I was on the right track.

Photo is taken looking up under the chimney cap...does seem odd that the gap is so uniform.

Dave