# Flashing this chimney/siding Intersection



## bilskro (Aug 11, 2016)

Trying to figure out how to flash this chimney properly. Rain just runs down the roof onto the chimney and then gets behind the siding. In the photo I already moved the ¾” trim board that ran down the chimney. The only thing stopping water from getting behind it is caulk.


I am not sure how to flash it properly. I am thinking L Flashing. I can grind the chimney down a bit to make it flat I think for the L-Flashing. That way it will be L-Flashing with siding coming down onto the L-Flashing like at a roof line. The problem is what to bed the L-flashing in that will stop water from getting underneath it; Tar, Geocel, Thinset mortar or something else?

Or is that a bad plan. Any other suggestions appreciated.


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## roofermann (Jul 7, 2012)

You should put a saw kerf into the new siding parallel with the slope of the chimney's shoulder and have the top of the flashing bent into the kerf.:thumbup:


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## bilskro (Aug 11, 2016)

I was thinking of cutting a kerf in the stone and bending the metal into that. Not sure how making a reglet in the siding would help keep water out.


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## roofermann (Jul 7, 2012)

bilskro said:


> I was thinking of cutting a kerf in the stone and bending the metal into that. Not sure how making a reglet in the siding would help keep water out.


A kerf in the stone? Really? You want the rain that runs down the siding to go away from the siding. Think Z metal, 1/4in into the saw kerf on siding, 4-5in tall and 3-4 in out onto the shoulder.


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## bilskro (Aug 11, 2016)

The problem is water is getting behind the siding where the stone is. I would be putting the L-Flashing behind the siding and cut the siding to be at least 1" above the L-Flashing. So water runs down the siding and onto the L-Flashing. But water from the roof is dumping on the chimney and getting behind the wood and caulk that was there. I am not sure if I put an L-Flashing with caulk under it that is enough. that is why I am thinking kerf or at least a kerf in the stone at the top.


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