The reason why the roof valley is such a sensitive area has to do with all the rainwater and or melting snow that accumulates and flows through the valley on its way into the gutters.
Valley of roof leaking.
Take measurements of your roof flashing most flashing is 14 inches wide but yours may vary.
Most roofers that install shingles will not have rubber membranes with them to do such areas.
When a shingle from either roof intersects and passes over the metal valley flashing it needs to be cut at an angle.
Most shingle installers will use a thick 30 lb paper as a base for the valley.
Because roof valleys function as a drain on the roof they receive as disproportionate volume of water every time it rains.
Follow these three preparatory steps to get ready to fix the valley leak.
A roof valley is very prone to leaks especially if you have an older roof.
The most common cause of a roof leak where metal flashings are used is shingles that have been improperly cut.
Many roof valley leaks are caused by roofing nails that have been poorly placed and are acting as a dripper feeding water through from the roof above.
Roof valleys if not installed correctly are one of the most leak prone areas on the roof.
Valley areas are prone to leak due to the lack of using proper materials.
Just like in nature a valley on a roof is designed to collect water.
Clear any debris in the roof valley and surrounding area.
How to fix roof valley leaks remove debris remove all debris from roof valleys so nothing is touching your roof re shingle roof valleys install ice and water shield under shingles or install metal roof flashing and re shingle the valley.
Most roofers that do shingles will use a heavy base paper instead of a rubber membrane.