How to Shingle a Valley
Roof valley installation has gotten complicated with all the flashing options, weaving techniques, and waterproofing requirements flying around. As someone who has shingled valleys on every roof type, I learned everything there is to know about proper water management. Today, I will share it all with you.
Why Valleys Matter
Probably should have led with this section, honestly—valleys are where two roof planes meet, concentrating water runoff. Proper shingling ensures water drains without leaks.
Valley Methods
That’s what makes valley technique selection endearing to us roofers—each method has advantages:
Woven Valley
- Shingles from both sides interlace across valley
- Good water resistance when done correctly
- Works best with similar roof pitches
Closed Cut Valley
- One roof plane shingles extend across valley
- Other side shingles cut 2 inches from centerline
- Clean appearance with good water shedding
Open Valley
- Metal flashing exposed down valley center
- Shingles cut back from centerline on both sides
- Best for high-water-volume areas
Preparation
- Install ice and water shield in valley
- Ensure proper underlayment overlaps
- For open valleys, install metal flashing
Installation Tips
- Never place nails within 6 inches of valley center
- Clip upper corner of shingles at valley angle
- Apply roofing cement under cut shingle edges
- Maintain consistent chalk line for straight cuts
Common Mistakes
- Nailing too close to valley center
- Inadequate underlayment or flashing
- Uneven cuts creating water channels
- Skipping roofing cement under cut edges
