ice shield or metal flashing in valleys

After browsing most of the shingle manufacturers' web sites, it seemed to us that consensus for ice shield. barrier was the norm. Su we had a roof done that way last fall and our roofing guy opined that it is pretty much the best way now. At this point we are having him do a reroof on a metal flashed job that has lasted way past the warranty. Some like the open valley metal flashing appearance-wise, but the ice barrier with closed valley looks pretty good, too IMO. Sounds like you are off to a good start with a good sub.

Joe

Metal valley flashing is used in open valleys. The Ice & Water Shield membrane can be used as valley flashing under woven or half-woven valleys. It can also be used under the metal valley flashing as a back up. The membrane cannot be used as the only valley flashing in an open valley - the membrane won't hold up to the UV.

Thanks for the diagrams RicodJour. The contractor will be doing a closed cut valley, per the NRCA guidelines you posted.