Roof Installation and Application Practices
What this domain tests
This domain tests field execution: how shingles, underlayment, flashing, fasteners, and ventilation are installed so water is directed off the roof and wind uplift is resisted. Questions often turn on sequence-what goes under what-and on details at penetrations, valleys, and edges.
Core rules and concepts
- Start with a starter course at the eave and rake where the covering requires it; it seals the edge and sets the shingle alignment.
- Follow the manufacturer’s nailing pattern. For typical architectural shingles, nails go above the exposure line, are driven straight, and are not overdriven or high-nailed.
- Drip edge at the eave goes under the underlayment; at the rake, it typically goes over the underlayment. Getting this backward invites water intrusion.
- Step flashing at sidewalls must be woven with each shingle course, not surface-caulked. Counterflashing laps over the step flashing.
- Valley treatment must match the manufacturer’s approved method-open metal valley, closed-cut, or woven-and the underlayment must be continuous beneath it.
- Ridge and hip caps are fastened per the manufacturer and are not substitutes for proper underlayment.
Worked example
On a 5:12 roof with architectural shingles, the crew installs eave drip edge over the underlayment, then starter course, then shingles with six nails per shingle in the manufacturer’s nail zone. At a chimney, they install an apron flashing at the front, step flashing along the sides interleaved with each course, and a backer flashing at the rear, then counterflash. They do not rely on a bead of sealant as the primary water barrier.
Traps that cost marks
High-nailing or overdriving nails; skipping starter course; installing step flashing after the shingles are complete; using surface caulk instead of counterflashing; and reversing drip-edge laps at the eave and rake.
Key points
- Nail placement and depth control wind performance.
- Flashing must be integrated with each course.
- Drip-edge lap direction differs at eaves and rakes.
- Valley method must be manufacturer-approved.
- Sequence matters: underlayment, flashing, then covering.