I have a chimney made of 16″ square chimney block and I want to install counter flashing. As can be seen from the photo, (if it attached) the base flashing is copper and so the counter flashing should probably be too to avoid galvanic corrosion. One thought I had was to cut a kerf parallel to the roof and install continuous flashing let into the kerf. My concern is water getting into the kerf, freezing and damaging the blocks. I think of the blocks as being somewhat brittle. I could go up to the next mortar joint and cut a kerf, but with 8″ high blocks, that might take a lot of copper. I wonder if peel and stick is made with copper facing. I’d like to avoid cutting into the blocks if there’s a good solution. Any ideas?
Thanks.
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Go with the big triangle method. Do not cut in plane to the roof.Do NOT.
What is the pitch?
We use a RT angle grinder and a 4 1/2" diamond wheel in the mortar joints..start at the bottom or apron and work up with the triangles. Roll a plug to hold the counters in the kerf till you Geocel them in for good. To make a plug use a snippet of CU about 1/2'' wide by 1 3/4 long..roll it sorta conical and crimp closed the fat end to make it flat enough to start in the kerf, then hammer it in, while keeping the counter tapped in tite.
If the plug bottoms out too soon, make it narrower, if it is too fat, make it shorter. I use two plugs per counter, one is behind the next counter up. Finish with the top pan, or a cricket..a cricket needs counters too.
Down the road here in Richmond.
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Thanks for the reply! The pitch is 9.5/12. Sounds like a good way to do it. Out of curiosity, what's wrong with cutting parallel to the roof?
Edited 2/3/2006 11:32 pm ET by KylefromKy
Likely to wind up with a weak corner on the block. I'd do it on stone, but block is soft enough to split off a corner.
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Hate to contradict my podgey, but on a block chimney, I'd cut a kerf parallel with the roof. Lay a 2x4 on the roof and slide your grinder down the top of it to keep the kerf straight. Cut it about 1/2" deep. Draw a pencil line 1st and see if you're going to dislocate any small corner chunks and raise your guide 2x4 up or down. The 8" blocks ceate a large overlap of flashing to block which might allow wind driven rain to breech the counter flash.
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Heck, glad ya did. I saw a block chimney break off from that kinda cut in a storm a few yrs ago. Mebbe the block was weak or the kerf too deep, but the 6' above the cut fell like a tree.
But that was pretty old block, mighta been other factors in its strength.
I bow to your superior knowledge master.
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A half inch deep kerf shouldn't be enough to compromise the chimney seriously. It was probably deteriorated from weather and creosote and the part below the roof was relatively stronger. Just saw the slate pics. Looks great.Birth, school, work, death.....................
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