- Apply a 36″ piece of WinterGuard™ Waterproofing Shingle Under- layment, or its equivalent, up the center of the valley. WinterGuard is applied directly to the deck. An alternative for WinterGuard is mineral-surfaced roll roofing. If shingle underlayment is used on the remainder of the roof, it should overlap the WinterGuard by 4″.
- Next, apply an 18″ – 20″ wide sheet of metal valley flashing over the WinterGuard in 8′ to 10′ lengths. Use a narrow band of roofing cement to fasten shingles that lap the metal. Preformed “W” style valleys are preferred.
CAUTION: Due to the expansion and contraction, a granular-surfaced valley liner under a metal flashing can cause abrasion to the metal from the friction. Alternatives to consider include sand or film-surfaced liners.
