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Paint over block chimney

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Okay I know its not recommended to paint over a chimney but its already done!
I got a call from a customer yesterday his chimney leaks only in the winter and leaks pretty bad too......
THe chimney is all 8" block that appear to be exposed aggregate? never seen that before. The chimney was painted about 10 years ago and looks like its doing very well with the paint but it has a leak at the crown causing the damage. I will be repointing the chimney and repainting.

What is the best paint to use? I was thinking maybe a stucco paint but I am worried it will trap water in the chimney.
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If the crown is suspect as the main source of trouble,follow the details in this article and possibly the problem will be gone.

As far as painting goes,my favorite is Thoro Seal however, the best results will be had with it over non painted block.
Check the cricket, if he is only getting water during the winter I would guess it's a flashing/ice issue.
Check the furnace flue if applicable...could need a re-line.Could also be slower drying cycles in the winter as well if water is penetrating the crown or any cracks on the stack.

As far as paint, Thoroseal needs virgin masonry to do it's job,...better off with Thorocoat or Thorolastic or any other high grade acrylic/
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Could be gas in an unlined flue causing moisture. Snow sitting on a cricket of some sort. I have one where the snow leaks in the j chanel on a flat roof where the chimney is. I gotta get out there and see what im going to do about that at some point.
Check out thorolastic by basf
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