Z-flashing

[Tisham Candella]

Sheetmetal fabricators will bend any shape flashing you require. Locally several of our lumberyards have metal shops too, and the rest can order flashing in from suppliers who typically also supply metal roofing panels.

On my deep energy retrofit of our house, I had to twice go to a local sheet metal shop to get custom metalwork; I guess that is the bad news. The good news is that the guy I worked with was a really cool blend of hard-core tradesman and innovative artist. He is the most pragmatic and creative problem-solver I have ever met. Pretty neat to see that in our industry.

Your local supply house should have 2'x50' rolls of aluminum flashing that your sub can form into whatever shape you need. We just finished siding and our detail had 3" of mineral wool and 2x4 furring strips. For the mudsill flashing, we went 2" up the wall, taped to the sheathing, came out 5" and turned under another 1/2" on the bottom. The flashing rolls are typically white on one side and brown on the other. For the window flashings where we had end dams, I needed to get a roll that was 2 sides white, which is an up-charge from the brown and white.

I got this idea from finehomebuilding. Extruding roll flashing through scrap wood or ply works great. No joints anywhere, makes a fast install. I would put a metal clamp over the edges of the form, the flashing has a tendency to cut into the wood like a knife after awhile.

Thanks for the responses. I've got a call out to a couple of local lumberyards to see if they can get me some custom z-flashing. One place said that it would probably be about $1/foot. In terms of my own time to rent a metal brake and bend my own flashing, that seems to be a good price.

1. It looks like you could replace rusty z-flashing without replacing the siding panels assuming that the panels aren't rotten. What I see is removing the nails along the bottom of a panel that is the top panel along a flashed seam. Then pry the top panel away from the structure enough to remove the old z-flashing, and insert new z-flashing. Then renail. Does this sound feasible? If not, why not?

3. As an interim cosmetic solution, I'm thinking that I could cover the rusty z-flashing with a 3" trim strip, and caulk it at the top so no more rain would get in to the z-flashing. This would stop the rust from spreading, and getting onto the panels. Then I could paint the panels and trim strips, and I wouldn't see any more rust. I've seen this done as a cosmetic feature, "concealing z-flashing", and I assume that it would also work for my purposes...

I've also been considering re-siding using vinyl, but would like to avoid that step if I can. I like wood, but I'm tired of rusty z-flashing bleeding rust onto the panels. I've also considered cedar shingle siding, but the T1-11 that I have is mostly the 3/8" variety (cheap *smile*).

Thanks for your comments. Question 3. above refers to having the rusted z-flashing in place, but covering the rusted z-flashing with a trim strip caulked at the top, so no more rusting. That shouldn't take that much caulk, and caulk is cheap compared to residing (which uses caulk, too *smile*).

I do have a quote out for replacing the T1-11 in this one bad spot with new T1-11 and z-flashing and priming and painting it. I'll see where that comes in, to see if it makes more sense than the interim solution I'm considering. I also have a quote coming for vinyl re-siding, but I'm expecting that to be quite expensive. Although I may decide to go that way for the long term, even though it isn't wood *smile*.

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