Two Ways to Flash Roof Edges
Protect the eave from ice dams and sideways rain
Step one in steep slope roofing is the edge flashing.
One common method is to lay the edge metal under the eaves membrane, and over the rake membrane. The layering uses gravity to direct water out of the assembly.
Another way is to storm proof the edge by folding the membrane down over the gap between roof deck and fascia, layering metal flashing on top sealed with another strip of flashing membrane.
Regardless of how you do it, make sure that the eaves membrane extends at least 2 feet inside the outer face of the wall, It probably means a second course of edge membrane.
Step by step:
- Overlap seams about 3 inches, depending on what the manufacturer specifies.
- Install drip edge metal to the eaves beginning at the back of the house, working toward the most visible section of roof, to avoid gaps that catch the eye.
- Seal the top edge of the eaves metal with flashing tape or a thin strip of roof membrane.
- Rake membrane only needs to be a single width and should extend up all of the rake edges.
- Work the edge metal up the rake from the bottom. The upper pieces should overlap the lower ones. Visible gaps between the flashing are less important than the water-injection system that would result from slipping upper pieces under lower ones.
- The bottom of the rake metal should extend past the eave flashing.
Sweating the details at the edges will keep ice dams and windblown rain out of your roof.
— Technical support from Doug Horgan, of BOWA, a Design, Build, Remodel, and Consultation company in McLean and Middleburg, Virginia and Don Shaw, of IKO roofing. Doug is also a member of our technical advisory team.