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Mono Pitch Porch

Birdie L | Posted in General Questions on

I hope I use the correct terminology, building a porch, which has a mononpitch, almost like a canopy or an awning. Searching for illustrations or technical data on how to flash the corner, where the side wall meets the porch roof.
Metal flashing will be tucked under the housewrap, but should the metal flashing extend over the porch by a few inches? How do you detail this corner section?

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Replies

  1. Expert Member
    Armando Cobo | | #1

    1. You want to install taped & shingled WRBs on the roof, making sure you run it on the walls by at least 3"-4".
    2. You can use a custom made, welded corner and straight or stepped metal flashing on or a peel & stick flashing WRB on the side of the walls and on top of the roof WRB. You want to have at least 6" on the wall sheathing and 12" on top of the roof WRB. Its a good idea to tape wall flashing before you install the wall WRB, as an insurance.
    3. Don't forget the kick-out flashing at the end of the roof and wall junction.
    I'm attaching a few of pictures I found on Google, but there is a lot more if you search for roof flashing.

  2. Birdie L | | #2

    Would you still use the drip edge and the kick out flashing on the corner of this? Not our porch, it this is similar to what I’m describing.

  3. Expert Member
    Armando Cobo | | #3

    Yes on the drip edge. No need for the kick-out flashing, I don't see any corner or wall end at the bottom..

  4. Birdie L | | #4

    This isn’t our porch, just an example. Would you do any extra detail at the point where the roof terminates at the side wall?

  5. Expert Member
    Michael Maines | | #5

    Birdie, I learned to call that element "base flashing," but in this article, Mike Guertin calls it "apron flashing," which is probably a better term: http://www.finehomebuilding.com/2015/05/13/four-steps-to-flash-a-dormer. It's behind a paywall but you might find a subscription or trial worth it.

    Basically, you should first seal that seam between sidewall and awning roof with a peel-and-stick membrane; at least that's what I like to do--I try to make the house watertight before any cladding is installed. Then install roofing, then install apron flashing that goes up the wall and over the shingles, at least far enough to cover the top row of nails, usually 3-5". Turning the lower edge down a bit, as Guertin shows in his article, helps keep a nice even line on the roof. Even better would be to hem the turned-down lower edge. But that's starting to get fancy.

    Edit to add: perhaps you mean specifically the intersection where roof rake (the trim on the sloped side) meets the wall, where in your photo they have turned down lead flashing over the ends of the shingles? While I like the idea for windy, rainy locations, it looks kludgy; usually there is dripedge along the rake, the shingles hang over by 1/2" or so, and the apron flashing is cut cleanly at the edge of the shingles.

  6. Birdie L | | #6

    Thank you very much

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