Cinder block chimney flashing


16 oz copper is fine. Base flashing should come out enough to cover nail heads in course below. 4" tall is fine 4" steps should be fine. Do you get snow where you are located?. The flashing on the top side should be minimum of 4x12, taller up the chimney if you get snow. Copper is pretty easy to form, a break is ideal but a piece of angle should work, don’t try to bend all at once. The hardest part will be bending the 3/4 or 1" offset in your z without a break. If you have a local mom and pop rental place that rents breaks you could cut and Mark everything and just take it there and pay them 20$ to use the break for 15 min.


I’m near Portland Oregon, not much snow where i live. Looks like i can get an 18" brake for less than $50 locally. Sounds like it would be worth it. Just need a copper supply and i can finish this blasted roof. Thanks for all your help!


Good roofing supply house should have 2x8 or 3x8 sheets in stock, at least all of the ones in my area do.

Get yourself a bag of copper or stainless steel rivits, either will take solder. Rivit your corners where they need to be. Take the piece back off, so you don’t burn the house down. You can use a plumbing torch on low heat, flux and solder, to solder your corners.


We dont have a lot of copper around here, and what does is a bit higher end than a standard supply house would carry. I found a sheet metal place that let me order cut pieces to save me a little labor. I am planning on soldering everything (off the roof of course). I have flux and solder left from my re-pipe, i assume that will work fine? Do you have a preference on copper or stainless for the rivets and nails? Thanks


I prefer copper rivets over stainless myself. Just because stainless are so much harder to pop! And also because stainless stay shiny forever. As for nails I wouldn’t really recommend either over the other in your situation.


Copper if you can easily get them, that’s what we use. If not stainless are fine.


Yeah i can get copper nails pretty easy here. Is there a preferred solder to use? I have about a pound of solid wire left over from a plumbing project i was hoping to use. Also, i’m not sure i understand where the rivets would be used?


50/50 lead/tin, the old plumbing solder normally works best, lead free works but patience is required. I normally bend the corners back on the base flashing, bend the first step around the base flashing, rivit, and solder the corners, the reverse goes with the top pan. Anywhere you plan to soldered needs to be rivited together first nice and tight. Once it’s rivited together you can pull your piece back off and solder on the ground, you will be able to flip it around and get the solder everywhere you want. Soldering verticals in place take some practice, much easier on the ground.


Got it, that makes perfect sense. Hopping for good weather this weekend to give this a go. Thanks!


Finally got my copper this week. Thought i’d post a couple pics. Its not pretty, but it shouldn’t leak. Still need to do the rear base and the counter. Slow going in 40 degree weather…


Looks good for a diy job, hell looks better than many pro flashing jobs in my area!


Looks great, are you using copper nails when nailing through the copper?


Yeah, spendy little buggers. Finished the base flashing yesterday. Stainless is OK to use as well, correct? The rear base will be under the ridge vent and i think 2.5" stainless nails will be a lot easier to find…


Stainless nails are fine.


Completed the base flashing. I’m concerned the reglet i have isn’t going to be wide enough though. Its about 3/16" right now, should i see if i can get that up to maybe 1/4"?


Did you wait to grind your slot till after your flashing was installed? If so that’s why you are having a harder time. Yeah I try to aim for 1/2 inch.


No, i put a slot in before i even bought the copper. But because i hadn’t worked with the copper yet i underestimated its thickness when bent. Not looking forward to the mess, but at least i have a nice straight edge all the way around.


I would just make a z flashing, 3" up the block, over the top of the 1x and down over the copper.