Metal Roof Open Valley Flashing Detail

Cad details document name pdf dwg download all cad construction details 37 1 mb 3 4 mb mc01 identification of roof areas 694 kb 167 kb mc01a single layer underlayment 678 kb 302 kb mc01b double layer underlayment 711 kb 322 kb mc02 vent pipe flashing 626 kb 349 kb mc03 valley.

Metal roof open valley flashing detail.

With a clean valley you can lay down some peel and stick roofing membrane. That flashing is left exposed so the roof has visible lines of metal running down the valley. An open valley relies on metal flashing for protection. After the underlayment is placed a pre bent metal valley lining is installed.

Closed valley s or open valleys. Install synthetic roofing underlayment or felt paper according to manufacturer specifications and then install the first piece of valley flashing. The shingles or slate must lap the flashing at least 6. The detail shows a typical open valley flashing for a shingle or slate roof.

Nrca lile recommends that roof valley flashing metal for open roof valleys should be 26 gauge 0 45mm galvanized steel or equivalent noncorrosive nonstaining metal. Two different cants are illustrated. For an open valley a sheet of metal usually steel sometimes copper is fastened to the roof deck. There are two common methods for completing the flashing of a valley in a shingle roof system.

Extend entire width of flashing completely to the bottom of the roof valley. One of the details that varies between homes is the method of flashing the valley areas of the roof. Some homeowners do not like the look of open valleys while others feel the metal accentuates the roof s shape particularly if copper or painted flashing is used. Drip edge metal valley flashing dormer chimney and kick out flashing shed water away from the connections between roofs walls chimneys and other building assemblies this collection of 18 articles animations and videos identifies the critical roof flashing areas illustrates durable roof flashing details and shows how to flash roofs right in the real world.

Roofing shingles are installed then cut and sealed where they overlap the metal channel. Lile points out that valleys lined with roll roofing are not as durable. Fold the top over the roof ridge and cut the bottom along the drip edge metal. When compared to a closed valley and open valley adds an additional layer of lining.

To understand what makes a valley either closed or open it is important to understand how a valley is constructed. This allows water to fall from the higher slope to the lower slope and prevents it from going under the shingles to the roof deck.