Wrap-around Porch Roof Flashing

[hagler]

I've just built a front porch where the top of the roof meets the house (a colonial house)--so the roof meets the house about 18 inches below the windows on the second floor and then wraps around the corner about 4 feet--the house is vinyl sided.
I have a few questions:
Going across the front of the house the run is 27 feet--I am using aluminum coil stock for the flashing--3 ten foot sections. Where I have to overlap the joints, I plan on soldering these joints with a proven aluminum solder that works (no flux needed, as I realize aluminum soldering is difficut--also, I tried sealing the joints and they still leaked)..How much should I overlap the joints?? Is 2 inches sufficient?
Also, I am using an 8 inch piece of flashing--4 inches up the wall and 4 inches on top of the shingles--with a 3/4 inch kick into the shingles? Is the 8 inches sufficient?
Also, can I solder while the flashing is in place?--I have to heat up the aluminum on top of 3-tab asphalt shingles and against the 1 inch insulation behind the vinyl siding--is this OK??
Where the corner of the house is, the porch roof wraps around this corner. How do you handle the flashing going around this 90-degree corner?? I plan on having the pieces of flashing meet at the corner--I will tuck them behind the vinyl corner post--but, how do you seal this joint?? Should I leave a 6-inch tab and bend it around the corner?? Any suggestions? Also, on top of the shingles there is now a gap because you have to bend it around the corner--can I just piece it in with a square piece and solder?
One more question (sorry so many of them): I had to cut the vinyl siding across the house where the roof line meets the house...Is J-channel the best option to hold this "loose" siding to the house now? Also, I have to nail the j-channel through the flashing into the house--correct? Do I need to seal these nails? - the nails will be about 2 inches above the roof line?
Thanks so much for the help--any suggestions are appreciated.

[tinner666]

6" laps, no solder. And same at corners with scissor lock of opposing pieces will do it with only a dab of caulk at corner

[hagler]

Thank you....Is there any way you can explain a scissor lock??

[tinner666]

I'll try. Instead of just lapping one around corner, then other, I like to lock them together. If the angled part of the 2nd. is going over the angled part of the first, I put the vertical part of the second BEHIND the vertical part of the 1st. Instead of straight cuts, do a VERy narrow pie slice TAKING OUT ONLY ABOUT 1/32" where the two pieces come together.
A couple of minutes practice with 2 pieces of scrap will make it all clear.

[98softail]

Is there any sort of flash-vent? I also have a wrap around porch and do not want to have to install roof vents. I have seen many different venting methods, and thought this would work.

Where the roof meets the siding/brick etc. cut back the sheathing like a ridge, then install venting fabric (cobra vent) only not as wide. Then cover it with flashing.

Has anyone tried this?

[tinner666]

One or more vent companies make various vented termination flashings. OR did none of the sites I wanted to link to had it listed.

http://airvent.com/professional/whyVent/evaluate.shtml

http://www.duraflo.com/_tier1.asp?x=8