Flashing & Waterproofing
Step flashing, counter flashing, valley flashing, drip edge, roof boots, lead flashing, and cricket construction.
- Explain the purpose of drip edge flashing at eaves and rakes
- Describe step flashing installation alongside vertical walls
- Identify the purpose and materials of counter flashing
- Explain the proper procedure for valley installation
- Describe the purpose and construction of a roof cricket
Lesson 1
Drip Edge & Eave Flashing
Purpose of Drip Edge
The purpose of drip edge flashing is to direct water away from the fascia and into the gutter. Without drip edge, water wraps around the shingle edge by capillary action and wets the fascia board, causing rot and damage.
Drip edge is installed along:
- Eaves (bottom edge) - installed under the underlayment
- Rakes (gable edges) - installed over the underlayment
This layering sequence ensures that water flowing down the roof runs over the underlayment, over the eave drip edge, and into the gutter. At rakes, the drip edge is placed over the underlayment so water cannot get behind it.
Drip Edge Materials and Dimensions
Drip edge is typically made from galvanized steel or aluminum in a minimum width of 2 inches on each leg. The lower leg extends down the fascia while the upper leg lies flat on the roof deck.
Roof Edge System
The purpose of a roof edge system on flat roofs is to secure the membrane at the perimeter, prevent wind uplift, and provide a finished edge. Common edge systems include coping caps, gravel stops, and drip edge fascia.
Drip edge directs water away from the fascia into the gutter. At eaves, drip edge goes under the underlayment. At rakes, drip edge goes over the underlayment. This sequence ensures proper water shedding at every edge.