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BigV · 09-09-2010, 05:32 PM

Answer:

I bothered because that was how I was instructed by the wrapper on the roll. One full width section down the valley would have accomplished the same thing. There would have been minor differences, the number of thicknesses, a crack in one can't spontaneously migrate to a crack in the next unlike a single section, super extra wide for a strip vs narrower protection offered by the "shingles", etc. A trade off. The real answer to your good question is that at the time of this project, I'd had exactly zero roofing experience. This whole project was "by the book" PLUS my own compulsion to overengineeer stuff like this.

That valley will *never* leak. The old roof is still there (and it was intact when I put this new roof on), multiple interleaved shingled layers of roofing paper (#15 I think) plus the handmade valley shingles, plus the roll roofing material is overlapped perpendicularly across the whole valley, plus each parallel course overlaps the other by 12 inches, secured by the tar roofing adhesive. 'Cause that's just how I roll (out the roofing material).

In the next section, I did have some much more troublesome valley work. The pitches of the two roof sections were not the same, and on one section the pitch changes, causing it to both bend upward and curve to the side (like a chine on a boat in the transition between the side of the hull amidships as it approaches the bow). Additionally, shingles over this valley were rotten and the metal valley itself was rotten (daylight into the attic--very not good). You'll see in a bit how I dealt with this one, but I used a product that might be similar to your IKO material. I'm happy with the choice so far.

And thanks for the compliment!

09-09-2010, 05:32 PM	#97
BigV Goon Squad Leader Join Date: Nov 2004 Location: Seattle Posts: 27,063	Answer: I bothered because that was how I was instructed by the wrapper on the roll. One full width section down the valley would have accomplished the same thing. There would have been minor differences, the number of thicknesses, a crack in one can't spontaneously migrate to a crack in the next unlike a single section, super extra wide for a strip vs narrower protection offered by the "shingles", etc. A trade off. The real answer to your good question is that at the time of this project, I'd had exactly zero roofing experience. This whole project was "by the book" PLUS my own compulsion to overengineeer stuff like this. That valley will never leak. The old roof is still there (and it was intact when I put this new roof on), multiple interleaved shingled layers of roofing paper (#15 I think) plus the handmade valley shingles, plus the roll roofing material is overlapped perpendicularly across the whole valley, plus each parallel course overlaps the other by 12 inches, secured by the tar roofing adhesive. 'Cause that's just how I roll (out the roofing material). In the next section, I did have some much more troublesome valley work. The pitches of the two roof sections were not the same, and on one section the pitch changes, causing it to both bend upward and curve to the side (like a chine on a boat in the transition between the side of the hull amidships as it approaches the bow). Additionally, shingles over this valley were rotten and the metal valley itself was rotten (daylight into the attic--very not good). You'll see in a bit how I dealt with this one, but I used a product that might be similar to your IKO material. I'm happy with the choice so far. And thanks for the compliment! __________________ Be Just and Fear Not.