Best way to flash this roof to wall intersection?

Posted by Wayne Whitney on July 8, 2009, 12:13 pm

> Not to mention the current roof flashing is a good inch or two away
> from the new wall. I don't know if there's enough flex to fit it
> under the siding without messing with the new roof. Will have to
> wait and investigate more when I'm on site next weekend.

I thought straightening the car port would eliminate that gap? I
definitely encourage you to get the car port sorted and firmly
attached to the house, although I can see how that might be more than
you want to tackle.

If you don't want to deal with the car port, you could fashion a large
piece of Z-shaped counterflashing that would attach to the wall and
extend over the roof step flashing. The lower leg would be exposed,
and the upper leg would tuck under the building paper and siding.

[Note Z-shaped means an offset with two 90 bends degrees, not the >90

degree bends in an actual Z.]

Cheers, Wayne

Posted by HerHusband on July 8, 2009, 1:18 pm

>> Not to mention the current roof flashing is a good inch or two away
>> from the new wall. I don't know if there's enough flex to fit it
>> under the siding without messing with the new roof. Will have to
>> wait and investigate more when I'm on site next weekend.

> I thought straightening the car port would eliminate that gap?

I didn't really check if the carport leans away from the house, but it
leans to one side about 4".

> If you don't want to deal with the car port, you could fashion a large
> piece of Z-shaped counterflashing that would attach to the wall and
> extend over the roof step flashing. The lower leg would be exposed,
> and the upper leg would tuck under the building paper and siding.
> [Note Z-shaped means an offset with two 90 bends degrees, not the >90
> degree bends in an actual Z.]

I will keep that in mind when I check things out this weekend, though I
wonder if I could just use a piece of straight flashing nailed to the wall
and extend down to overlap the step flashing of the roof? It would slope
outward slightly, but in the grand scheme of things that wouldn't be a huge
problem. I could cover most of it with the siding so it wouldn't be so
obvious.

We were really tired when we finished up last week, so I'm mostly going
from memory and photos taken from a distance.

Thanks for the ideas!

Anthony

Posted by Wayne Whitney on July 8, 2009, 1:58 pm

> I will keep that in mind when I check things out this weekend,
> though I wonder if I could just use a piece of straight flashing
> nailed to the wall and extend down to overlap the step flashing of
> the roof? It would slope outward slightly, but in the grand scheme
> of things that wouldn't be a huge problem. I could cover most of it
> with the siding so it wouldn't be so obvious.

Well, my thoughts are that the way to go really depends on the nature
of the gap. If the gap is permanent, and won't change or shift if you
ever straighten or reinforce the car port, then you can go with a
permanent solution. I would install a filler board between the wall
sheathing and the roof step flashing, nail each step flashing to the
filler board at the top, and then install a Z counter-flashing.

But if the gap is a result of the carport's settlement, then I would
think you'd want to preserve the option to straighten the car port at
some point in the future without redoing too much of your current
work. In that case the straight flashing seems like a good solution,
although I don't know how well you'd be able to flatten it should the
gap be removed by future work on the car port.

Hope this helps.

Cheers, Wayne

Posted by HerHusband on July 8, 2009, 5:02 pm

> I would install a filler board between the wall sheathing
> and the roof step flashing, nail each step flashing to the
> filler board at the top, and then install a Z counter-flashing.

Maybe I'm picturing this wrong, but wouldn't Z-flashing create a "gutter"
of sorts?

I know this is common for deck ledgers, between plywood sections on walls,
and whatnot, but those are level. Since this is on a slope I would think
any water running down the wall would hit the Z, and run down along the top
of the Z to the bottom of the roof. Then I'd have to devise a "kickout" of
some sort to keep the water from funneling behind the siding.

In contrast, a straight flashing (even if sloping away from the wall
slightly) should let water drain directly off the wall onto the roof.
Though I'd still have to take care of the detail at the bottom, maybe
tucking the bottom row of siding "behind" the flashing, so any water at
that point would be directed out.

Am I missing something?

> Hope this helps.

Yes, thanks, I appreciate the feedback and advice.

Take care,

Anthony

Posted by Wayne Whitney on July 8, 2009, 5:29 pm

> Maybe I'm picturing this wrong, but wouldn't Z-flashing create a
> "gutter" of sorts?

Yes, you're absolutely right, so it would require its own kickout
flashing, which would tuck under the high leg. The bottom-most piece
of step flashing also should be replaced with a kickout flashing, as
you have the same gutter effect there.

The instructions I used to fabricate kickout flashings can be found at

this web site: <http://www.kickout.info/csto.html>. They are talking

about stucco siding, but the principle is independent of the type of
siding.

If the side-wall/roof gap is permanent, then an alternative to the
Z-flashing is to redo the roof step flashing so that the upper legs
are against the house. It would be fine to have a small exposed
"valley" on the roof against the house, so you wouldn't have to change
the roof shingles at all. It shouldn't be too hard, once you remove
the existing flashing, which is nailed to the roof deck. You would
just slide each piece of step flashing under the row of shingles, and
nail it to side wall only.

Just a disclaimer: I've only actually had to do this once, most of my
understanding is theoretical.

BTW, it is also a good idea to have a horizontal joint in the building
paper at the height of the kickout flashing, with the lower piece of
building paper going behind the kickout flashing, and the upper piece
going over the kickout flashing.

Cheers, Wayne

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Best way to flash this roof to wall intersection? - Page 3