I am going to have new composition roofing put on my house. My question is this: There is metal flashing around the perimeter of the roof under the shingles that bends over the edge of the roof about two inches vertically. Do I need to replace this flashing when I have the new shingles put on? (The roof plywood under the shingles is still in good shape.)

It depends on whether the metal flashing, as you refer to it, is rusted; if you want to change its style or color; if you even want to replace it, since it is not required by code; and if you currently have a true drip edge flashing (as it is referred to in the industry). It's possible that you have nosing, which is commonly used as a drip edge, but it doesn't keep water runoff away from the fascia board.

copyright by Leon A. Frechette/C.R.S., Inc.

A drip edge is a modified L-shaped flashing and there are two basic styles on the market available in galvanized and aluminum. The aluminum flashing normally has a baked-on enamel finish in white or bronze (brown), although custom colors are available by special order.

Style D, my favorite, protects composition shingles at the roof's edge by providing a 7/8-inch cantilever over the fascia board. It also supports and protects shingle edges when a ladder is leaned against them. The hemmed drip edge at the bottom of the flashing helps keep water away from the fascia board. The Grip Edge, on the other hand, isn't designed to support shingles. If shingles overhang the edge, then over time with heat and snow loads, the shingles will curl down toward the ground.

A drip edge is used along eaves (overhangs) and rakes (gable ends) of the roof to direct runoff water into the gutters and away from the fascia. Drip edges should be placed under the roofing felt at the bottom edge of the roof and over the roofing felt on the gable ends. The drip edge shouldn't be installed against fascia boards but held out 1/4 inch before nailing to achieve air space. The rake drip edge should always overlap the eave drip edge at the outside corners.

Now that you know the difference between nosing and drip edge flashing and correct drip edge flashing installation, you can determine what you have and how to proceed before installing your new composition shingles. Good luck with your project!

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C.R.S., Inc. · Spokane, Washington · USA