You really have to neglect your chimney/roof to allow things to get this bad. I flashed this chimney for a friend of a family member, I only charged the guy a couple hundred bucks, he paid for a bundle of shingles and I supplied the Resibond and solder so I basically worked for free on a Sunday .
Can't get rich on every job I guess 😆
These guys came into work and ordered about 10 different lengths of gutter, as I'm looking over their paperwork I see two 36 foot lengths and then a 63 footer, I walked out to ask if maybe someone made a mistake but nope, they sure enough wanted a 63 foot gutter. So I ran off all the different lengths and tried to help these guys as much as I could, but of course that long of a gutter being hauled on a pickup truck was comically long and you may be able to see the wrinkle they make towards the back when they were trying to load this thing.
I had a good laugh and then went on about my day.
I put 64 foot in the title because I usually run them about a foot longer than what's on the paperwork so it ended up being right at 64 foot long.
I use galvanized sheet metal, Resibon to fabricate my chimney metal. I use 50/50 solder on the seams, Stay Clean flux works great for this stuff, and I use mortar/sand mix to tuck point after the metal goes in.
I took a full time job with a big company, but I still get out on the weekends and do this stuff on the side when I can.
You do have to paint this metal and that's pretty important for extending the life of it, maybe scrape and paint once every 10 years or whatever, but this flashing can last 30-40 years or more.