sheathing/shingling a roof with a pitch change--how to bridge a 2" gap?

[MikeT]

On my Victoria's Cottage, I decided to change the pitch of the roof over the kitchen bumpout.  That means I am going from a 12:12 to a 4:12.  While I am using the same rafter size (2x12s), on the bumpout the seat cut in the birds mouth is such that there is a 1 1/2-2" drop between where the roofs intersect.  Should I bridge this with a layer or two of luan?  Or should I use a narrow strip of 1/4" and build up the lower roof a bit before putting on the felt.?  Or should I put some Ice and Water Shield over the gap and then felt over it and remember the gap when shingling?

Thanks,
mt

[Redoverfarm]

Mike if it were mine I would place a rigid material on the horizontal plane between the overhang sheeting down to the porch sheeting.  That is providing you have enough overhang on the 12:12.  Then I would use a flashing between the two roofs.  Maybe even use an "ice guard" first to flare out upon the porch "felt" and then follow up with the flashing woven into the shingles on the porch.  I am not real sure what the shingles will do at that angle to make them stay in the valley of the porch pitch.  With metal roofing they make a pitch change that can be installed but with shingles I am not real sure.  If you are in a snow region the biggest problem you will have will be that the snow will almost stop when landing on the 4:12 and when it starts melting it may tend to back up the roof similar to the eve icing problem.

[ScottA]

I think I'd bridge it with sheet metal bent to match the pitch change, either copper or galvanized and not shingle over the gap but treat it like a valley. Stopping the shingles at the bottom of the 12/12 and restarting on the 4/12 with a small gap between. The metal would be under the upper shingles and over the lower ones. You'll want to seal the lower edge of the 12/12 with ice guard most likely since snow is going to collect on the 4/12.

[NM_Shooter]

I think I'd bridge it with sheet metal bent to match the pitch change, either copper or galvanized and not shingle over the gap but treat it like a valley. Stopping the shingles at the bottom of the 12/12 and restarting on the 4/12 with a small gap between. The metal would be under the upper shingles and over the lower ones. You'll want to seal the lower edge of the 12/12 with ice guard most likely since snow is going to collect on the 4/12.

Ditto....

-f-

[new land owner]

I am planning something similar however my pitch will be an 8 12 to a 4 12.  With this transition would you need the metal flashing or would the shingles cover this area?

[glenn kangiser]

Seems to me if you have snow and ice loads, it would want to tear the shingles off the 4/12 transition without the flashing to break it loose.