Roofing/shingles question

[Devils Advocate]

I built a new porch on my existing house. The porch is a 4/12 pitch and it extend in over existing roof about 6 feet. The 4/12 roof on the porch is facing a different direction than the roof on my house......lets say the porch is facing south and the house is facing west.....I mean the peek.

My question is what is the best way to install the shingles where the roof in the porch meets the roof in the house. I was thinking cut the shingles on roof the same angle as angle on porch.......then try to pry up on existing shingles to fit flashing under......the lay shingles on porch and don't spare the gum.

Any ideas?

[Tom]

Some guy wrote:>I built a new porch on my existing house. The porch is a 4/12 pitch and it

Check out the instructions for a "valley" on the back of a bundle of shingles. Think of how the water will flow over the areas in question, then apply in accordance with that information. Try to spare the gum.Tom Work at your leisure!

[Bruce]

If it is just a matter of connecting the porch roof to the main roof I would use 20" galvanized valley flashing under the last row of shingles on the main roof, and extending it over the top row of shingles on the porch roof. Leave about 3" extended from the two sides of the porch roof.

You can put some roofing caulk, like Sonneborn NP1, on the porch shingles where they will be covered by the valley flashing--but don't try to use caulk or tar to waterproof the area--that's a mistake.

Also, where the structural member of the porch connects to the main roof at each side, I would install tin shingles, or a fabricated piece of flashing, to divert the water around that area.

A.&B. Construction