GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Where do I buy Z flashing for exterior foam?

jay443 | Posted in Energy Efficiency and Durability on

I’m working on putting together a list of supplies that I’ll need for my residing project. I’ve read all of the articles here about how to use exterior foam and I’m planning on using 4 inches of foam on my house in Minnesota.  But I’m having trouble sourcing z-flashing that wide. Everything that I find seems to be much smaller (more narrow) than the 4 inches that I’ll need to project the foam. 

Does anyone have a good source? 


GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. Expert Member
    Peter Engle | | #1

    Most contractors would form that onsite with a sheet metal brake. If you are going to DIY, you might be able to rent one.

  2. Expert Member


    Sheet metal 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.

  3. Peter Yost | | #3

    Hi Jay -

    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.

    Hope you find the same.


  4. Jon_Lawrence | | #4


    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.

  5. user-6185887 | | #5

    Please think carefully about where you use metal going from inside the insulation to outside. It could become a heat sink transferring heat very effectively.


  6. natesc | | #6

    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.

    For things like sill pans you probably need to just rent a metal brake though.

  7. Expert Member
    BILL WICHERS | | #7

    You can buy a cheap sheet metal brake from harbor freight. There used to be one called the “big bendito”. The cheap brakes can’t do much (they’re basically a few pieces of angle stock with some handles and hinges welded on), but they can usually make basic light gauge flashing details. It might be cheaper to just buy one rather than renting.

    If you only have a few simple pieces to make, some heavy steel angle stock and C clamps will work. I wouldn’t recommend this for any more than maybe one or two pieces though since it’s just too much work to setup for each bend.


  8. jay443 | | #8

    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.

    As an additional question, is there a diagram/picture of the details of how the bottom of the wall should all be integrated together? Just want to be sure that I get it right.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |