What You Need to Know About Valleys
The valley of a roof is when your roof V’s together forming a “valley”. It is also known to bring two slopes together. Because of the volume of water and the lower slope along valley lines, valleys are very vulnerable to leakage. The valley has multiple reasons for its vulnerability - Another popular known reason is due to installation errors. Open valleys should be protected by a combination of ice and water shield and metal or one or the other.
A proper open valley application:
1 row (3’) of ice and water shield is applied in the middle of the valley
A W or V shaped piece of metal is installed on top of the ice and water shield.
Shingles are cut along the line created by the 2nd row of the ice and water and the metal remains “open” to carry the water off the roof.
Two common metal valley designs include:
V - Where one bend is made to match the angle of the roof slope
W- where a bump is bent into the center to prohibit water from entering under the shingles
You can also have valleys without metal and ice and water with still having correct installation. These are called closed valleys.
Closed valleys are covered using the shingles or the primary roofing material
that is being used on the roof.
Two common closed valley styles include:
Woven style - Where shingles are overlapped across the valley on the opposite slopes
Closed Cut - This is where the shingles look like the roof is coming together and forming a straight line down the middle.
Most installation errors are where we see the valley installed backwards. The shingles are going against the water flow which is forcing the water to go downwards into the attic space instead of flowing through the valley into your gutter system.
When this happens we are forced to take out the whole valley, install an ice and water shield, and then replace the shingles with matching roof material presented on the roof.
If you have anymore questions on proper valley replacement or you are concerned about your valleys. Please feel free to contact us here.