To understand what makes a valley either closed or open it is important to understand how a valley is constructed.
Roofing a valley with flashing.
If eaves flashing is used it should cross the valley centerline each way and be installed before the valley underlayment see eaves flashing discussed in roofing underlayment best practices.
Install valley battens on both ends of the roof valley then attach first flashing 3 4 inches over the roof flange and another 3 4 inches over the fascia if any is present.
Make sure to cover the gap at the bottom of the raised ridge.
Recommended procedures of basic valley flashing installation.
Apply an approximately 3 inch.
To splice the pieces add roofing cement to the lower piece and install the upper piece with at least a six inch.
Closed valleys or open valleys.
One of the details that varies between homes is the method of flashing the valley areas of the roof.
There are two common methods for completing the flashing of a valley in a shingle roof system.
Only nail at the edges with only enough nails to.
W valley flashing protects the critical area of your roof where two slopes come together to form a valley.
Drip edge metal valley flashing dormer chimney and kickout flashing are types of roof flashing that shed water away from the connections between roofs walls chimneys and other building assemblies.
When properly installed w valley flashing will reliably channel run off water down the roof and into the gutter.
Next install a 36 inch wide strip of self adhering bituminous membrane in 10 to 15 foot lengths up the valley.
Ensure ice and water protector has been installed along the valley first.
Then install a non corrosive metal valley flashing of 24 minimum width lap successive sheets of metal flashing a minimum of 12 inches and seal laps.
Snap a chalkline 2 to 3 inches past the valley center on the top layer of shingles.
Now nail this first flashing at both its far ends.
Lay one and two tab shingles as you near the valley so full size shingles will run across the valley.
Cut the bottom edge and fold it down over the drip edge.
Step 6 install the flashing.
Install an underlayment centered in the roof valley.
Roof one side of the valley running the shingles across it.
Be sure to check local building codes to ensure you have the proper width for your application.
Fold the top of the flashing over the ridge.
Then starting at the base of the.
Stop nailing 6 inches from the center.