What is the right order for roof flashing installation?
Short answer. Flashing goes on in the same direction water flows, from the bottom of the roof up: drip edge at the eaves, membranes and underlayment, drip edge at the rakes, valley lining, kickouts, then apron flashing, step flashing course by course, pipe boots, and head flashing and counterflashing as the shingles climb. Each piece laps over the one below so water never meets a seam.
The sequence on a shingle roof
- Eave drip edge fastened along the eaves, with underlayment lapped over it.
- Self-adhered membrane in valleys and around walls, chimneys and skylights. Most of Georgia does not require an ice barrier along the eaves by code, but membrane in valleys and at walls is good practice.
- Underlayment over the field, lapped per the manufacturer.
- Rake drip edge over the underlayment along the gable edges.
- Valley lining centered in each valley before shingles cross it.
- Kickout flashing at the lowest point of each roof to wall intersection.
- Apron flashing at the downhill side of chimneys, skylights and walls, over the course below.
- Step flashing one piece per course as shingles climb along walls, chimneys and skylights, each at least 4 by 4 inches, nailed to the deck only, never to the wall.
- Pipe boots as courses reach each pipe, lower flange over the shingles and upper flange under them.
- Head flashing or back pan on the uphill side of chimneys and skylights, with a cricket behind chimneys wider than 30 inches.
- Counterflashing set into reglets at masonry, or tucked behind housewrap and siding on framed walls.
- Hip and ridge caps last.
The checks that matter
No fasteners in the water path, no reused rusted metal, and no spot where sealant is the only barrier. If a roofer cannot explain how water moves past each piece, keep asking.
See drip edge explained, ice and water shield in Georgia and roof flashing explained.