Open Metal Valley Roofing

I m sure they are there for a good reason.

Open metal valley roofing. Roof mastic applied along sides of valley flashing. A closed valley may be just fine given the budget and type of roof. All shingles removed from closed cut valley. Ice barrier underlayment installed in roof valley.

An open metal lined valley properly installed is functionally better long term. Metal roofing and flashing details are a bit funny that way. Roofing shingles are installed then cut and sealed where they overlap the metal channel. This valley flashing material can be manufactured from any metal that will resist the effects of weather acid rain and other contaminants.

If the metal expands and contracts you could get some minor oil canning but nothing that effects the integrity of the valley. I ve seen heater cables installed over metal valleys. From a more opinionated viewpoint an open metal lined valley has a cleaner and more appealing look. With a clean valley you can lay down some peel and stick roofing membrane.

Fold the top over the roof ridge and cut the bottom along the drip edge metal. Entire width of new metal flashing properly extends over fascia at bottom of roof. In comparison to a closed valley an open valley adds another layer of lining into the valley. The following photos illustrate removal and replacement of a closed cut valley with new open metal valley shingles being removed in closed cut valley.

Open valley when compared to a closed valley and open valley adds an additional layer of lining. After the self adhering underlayment is installed across the valley a pre bent metal valley lining is installed. The metal is usually pre painted to best complement the shingles color blend. First clean the debris out of the valley including sawdust nails and whatever else is in there.

Metal valley does not extend more than 8 outward from the valley whereas shingles can go as far out as you want them to. Installation instructions often call for avoiding fasteners except clips or through slots but roof penetrations and many flashings like drip gable and end wall flashings are fastened directly and seemingly do just fine. For an open valley a sheet of metal usually steel sometimes copper is fastened to the roof deck.