Valley question

i will be redoing my roof in the next couple of weeks and i have one question about a one of the valleys. i have a picture and im trying to get it uploaded but it may be simple enough for the pros to just answer off hand. the roof/valley changes pitch about 1/4 of the way down the valley…the upper half is cut on one side and the lower half is cut on the other side. does this make any sense? any suggestions? i will try and get this pic posted.

The steeper slope, or the slope with the larger volume of water running downhill should be the side that the shingles get cut on.


so if i cut both on one side it would be fine?.. or should i do it like the previous roofer did?

%between% my roof is identical to this and everyone on this forum said it was done wrong…what is the correct way to cut it seeing as though it has different pitches?

Use “w” flashing

whats that?

you can cut it all on the same side when you reroof.

whoever put the old roof on felt the need to do it that way.

it probably works.


sweet which side is best to cut in on? thats really what im after

Its a valley flashing with a “peak” in the middle that keeps the water from flowing from one side to the other.It also keeps the metal from buckling from expansion and contraction.These valleys(IMO)look nicer and its the only way I do mine.

id rather just cut it, just need to know which side

Run the dormer side under and cut the main roof side as the old roofer did at the top of the valley.

thank you for the info

ditto johnk.


what would happen if the main roof ran under the dormer side and then cut the dormer side?

You asked,we told you.Why does it matter?

curiosity…i like knowing why something is wrong as well as right

Water can flow up the slope of the shallower pitch or the lower roof valley from the long cascading water fall coming down hill.

Minor possibility, but why take the chance.

Winter areas are more imperative to do it right and I imagine very windy areas too.


The same as what is happening now.