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Discussion Starter · #1 ·
Hi all,

I am looking to get my chimney re-flashed.

Based on my research, the best practice seems to be to install counter or cap flashing connected to the chimney that laps on top of the base/step flashing but does NOT attach to the roof surface, to allow for differential expansion.

Also the counter flashing should be inserted into a grove cut into the mortar joints of the masonry and then mortared or caulked in place.

I've spoken to a number of roofers in my area, and no one seems to follow this method.

Everyone so far says they just caulk the top layer of flashing against the masonry chimney surface instead of inserting it into the mortar joint between the bricks.

Also people seem to connect the counter flashing to both the chimney and the roof surface.

Is caulking considered an acceptable alternative to putting the flashing into the mortar joint, or are these roofers just not following best practices?

Thanks for any input.

Sources:

https://www.discoverhorizon.com/hrb/article.aspx?ASKID=115&DROPDOWN=3864
https://homeguides.sfgate.com/counter-flash-chimney-43294.html
https://www.thisoldhouse.com/roofing/21014936/leakproof-flashing
 

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Maybe 1 other roofer where I live grinds our the mortar on shingle roofs
It is best practice but not too common anymore
If they do a decent surface mount it should hold up a reasonable amount of time.
 

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Discussion Starter · #3 ·
Thanks Pat for your reply.

Do you happen to know anyone to the east of GTA (let's say, between Ajax and Belleville) who will set the flashing into the mortar?

Given the cost of re-flashing, I'll have more peace of mind knowing I don't have to worry about a caulk joint failing.
 
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