Here's how I find them. The upper corner was done to hide all the metal and look really neat. The result? A place where water is forced to infiltrate the roof. There is a large hole there between the back pan and the step-flashing. Also note that there is no leeway for chimney/roof structure movement either. For hundreds of years, it's been common knowledge among masons and carpenters that wood and masonry settled independently of each other. A proper rear pan or cricket will extend past the corners far enough to ensure a 2" allowance in movement.
Here, I've cut the flashing to fit the material used to do the roof. In this case, slate. Testing for fit. Here, I've put about an inch of caulk bead to help fill any discrepancy in the fit.
I don't bother soldering these. There is no need to. If you do, you end up with this. The exposed metal is well below the corner. And look how it looks from above. The picture was taken from above. I could stick my finger in the hole below this corner. Most of the water goes under that slate. Where to? I don't know, but who wants water under the roof? Nor does it allow for structural movements. The same problem exists when using shingles too. This is corner was very neatly done. Neat, but very wrong. Where is the water going? It's obviously going under the roof. No one knows where it will come out again. Living room, maybe?
What you have then is hidden flashing that doesn't work as it was meant to do. A glance at the first picture gives a good view of how the water will get forced under the roof. The second picture shows how restricted the water flow is around that corner.
When I finish my un-soldered corner, you have plenty of metal showing, and an unrestricted water flow. Notice how the water is forced away from the corner. And on top of the roof material. That critical area will never even get wet unless there is a blowing wind. And if you look at how it went together in the previous pictures, you'll realize that it still can't leak. The cut stops about 2" from the brick. By turning the outer edge of the back pan downwards, the water wicks to the outer edge and has no reason to wick under the pan. I've seen chimneys done this way, the house has settled, the chimney is now leaning to one side or the other, you can look under the pan through a 2" gap, slide your hand into the gap, and it still doesn't leak!
I much prefer the ole style with tinner's wings on the
corners. The style dates back centuries before caulk was commonplace. No
reliance on caulk or solder as the metal hides the corner detail from windblown
rain and snow. It's ideal for rookies and your work can be less precise.
Now, for the front corners of a chimney, skylight, wall, curb, or whatever, tinner's wings are the way to go. This chimney sports full wings, and I didn't detect any caulk under them either. The apron extends about 5" past each corner, and is cut about 1/8" wider than the chimney for a super tight fit between it and the first step flashing that comes around the corner. Water running down the roof misses the apex of the corner by 5". Only thing I didn't like was the 2" fold around the corner, with the counter-flashing. Never fold less than 4". A 4" fold gives the corner a more watertight fit, and if you're using mortar nails, or zanchors, you have much less chance of spalding the mortar.
You'll have to look twice at this one! It's a modified tinner's wing. It's upside down and I made the cut to within 2" of the corner. Then, I doubled the piece over to get rid of the sharp cut edge. Here's the apron at the front corner. It sticks out about1/8" from the brick. Here's the modified tinner's wing installed. Though the step flashing extends all the way to the bottom of the apron, the folded portion is a little more tightly folded around the corner. I put a little caulk in the corner before setting it in place, as a backup defense. Just hedging my bets, as the saying goes. The folded covers the apex of the corner to prevent blowing water issues.
Both types are 'bullet-proof', and I believe idiot proof too.
Here are a few pictures of some jackleg chimney repair work donated from Huntsville, Ala. Not very pretty. No tinner's wings to carry water past the corners. Corner cuts are wrong. The rear pan actually disappears under the roof somewhere. So does the water, obviously. Here are the close-ups of the front corners. Looks like a 1/2" hole to me. Anytime the corner is cut close, no matter how tight it's done. You're 100% dependant on caulk to prevent water intrusion. A picture of the other corner. Smaller hole, but it's still a hole.
Do you have a leaky chimney that needs repair? I specialize in fixing those hard to fix problems that seem to have been leaking since the house was built. As you can see, I don't use roof cement to make repairs, ( or even on new work!! ). This chimney is in a valley which is the wrong place to put a roof penetration! The original roof leaked, and several repairs later it still leaked. The owner finally found me and has been a happy camper since.
I am not the only roofer with the ability to make proper roof repairs, but if you're looking at this, you know you have found one with the skill to do the job. Should you keep looking for another one?
Is your chimney in the ridge? The step flashing should be scissor-locked together. No matter how much the structure settles, no leak will develop there.
The procedure for scissor-locking is thus: Of course, these pictures were done on the ground to show the technique. The final lock is made so it fits the ridge being worked on.
Chimney Repair Request
Faulty Vent Installation
Though not a chimney repair, the example below is the
type of work you should expect to when going for the low bidder. The installer
messed this up, and still not knowing what to do, he came back to do the repair
work with roof cement. Since this was still under 'warranty???', I didn't
bother to quote a price or make a repair.
Want to see how a vent is supposed to be installed? Power Vent Installation
Albert's Roofing Construction Partners
Albert's Specialty Slate Roofing and Window Flashing Co., Richmond, Va.