Metal Flashings: Wall leg height ?
How tall should the wall leg of a metal flashing be in order to resist wind driven water?
Everything you find at the typical lumber yard has between a 1 in. tall and a 2 1/2 in. tall wall leg. When you figure that you need to leave between a 3/4 in. space (vinyl) to a 2 in. space (fiber cement) above a deck, roof surface and so on, the cladding won’t cover those puny flashing legs (or the housewrap will end up exposed).
Think of all the flashings that go on a house:
deck ledgers, ‘band boards,’ window heads, door heads, gable returns, sidewall-roof flashing (step flashing), vertical wall to roof flashing (like the front of a dormer), chimney flashings……
There are a lot of places where water can get in and flashings are our first line of defense – and those wall legs have me worried.
How tall do you make your wall legs if you make custom flashings?
How tall do you think the wall legs should be to be effective?
What resources have you seen for information on sizing flashings?
Thanks for your ideas.
Mike
Replies
I generally custom order z-metal flashings with a 3" wall leg and tape them to the wall with 6" Vycor. For window heads and other horizontal trim there is generally about 5/8" showing. If I know the trim color I order the flashing in matching painted steel from a metal roofing vendor.
For a deck ledger, where a 1" decking board and a 3/4" gap up to the siding need to be accommodated, a larger wall leg is better. Trying to remember when I last did that a couple of years ago... I think I ordered 6 x 2 x 1/2 flashing.
There is nothing off the shelf here that I can use. The only z-metal is the silly stuff the sell for t1-11.
I've bent and installed miles of flashings. I go 2" up the wall unless it's a special situation. Even though the Hardi spec says it should be 2" off the roof, I've never seen it more than an inch and usually about 3/4". We mostly use copper and if the flashing goes much higher, the siding nails end up through it and since the siding guys seldom use stainless nails, the nails end up corroding.
If we're flashing to brick, a step flashing much taller than 2" makes the counter flashings too tall to my eye.
In 20 years, I can't ever remember a call back where the solution was a taller leg on the step flashing.
http://logancustomcopper.com
http://grantlogan.net/
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I married my cousin in Arkansas - I married two more when I got to Utah. - the Gourds
I've always made 90% of my own flashing out of 24" x 50' rolls of smooth coil stock. Typically I'll cut two 12" rips and bend both in half, giving me a 6" x 6" flashing to cut into steps or use continuous. Overkill? Probably. Cheap insurance? Most definitely.