Flashing Around A Bay

warrenc

My second storey addition is a framed bay, with walls at 30, 60 and 90 degrees. There is a lower roof sloping up and surrounding this bay. Where does the step flashing start, as soon as the roof starts to slope up against the wall, or when the angle becomes greater that 45 degrees.

Tom R

I'm not exactly understanding your question, - - but either way, - - you definitely need flashings 'anywhere' a roof meets a wall . . .

warrenc

Yeah, I know I didn't explain it very well. I will try again.

I had framed a second storey bay onto a house approx 7' x 14' using 5 walls at 30 degrees to each other, forming a somewhat circular enclosure. There is a porch roof that slopes up and meets these walls. As it goes around the bay, the angle at which this porch roof meets the walls changes. The first wall it meets, it hits it at right angles, so a simple flashing is needed. Then the intersection starts sloping upward at about 30 degrees at wall #2. This changes to about 60 degrees at wall # 3. Finally after it wraps around this wall, the roof is now parallel to the wall face. I know I need step flashing where the roof is parallel, but what about the other two walls.

reveivl

You need the step everywhere except the 'first' wall. Imagine you're a drop of water trying to get into the house!

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River Rat Dad

step flashing is needed when the roof line runs straight uphill. If it runs at an angle, a flashing over the shingles is needed.
My rule is "Think Like a RainDrop". Assume water wants to flow downhill as directly as possible and your job is to accept that fact and work with it. When you look at those side walls on bays you will see that water can get under a shingle if it is step flashed only. A counter flash over the shingle is the best way, although it is less attractive.