Installation should require
- following manufacturer specifications
- ensuring that the roof covering line is straight, even, and parallel to the valley
- following specifications, without harming the flashing.
IRC: Chapter 9 covers flashing details and material requirements for each roof covering in each material section.
Process/Skill Questions:
- What are two common methods of installing composite shingles in a valley?
- What is the purpose of underlayment in a valley?