Roof Flashing

Any handyman can tell you the important role roof flashing plays in avoiding costly leaks. Using the proper flashing in it’s proper place a good start, but keeping it in good repair will avoid costly repairs to the interior of your house. Inspecting the flashing from the exterior is a good start, but the real story is revealed from the interior of the attic. For example, valley-pan flashing can appear in good condition from the surface, but that is only part of the story. The way it was installed is not apparent from the surface, and improper installation will cause leaks that can only be detected from the underside of the roof.

Here is an example of questions I receive about roof flashing.
Question: We recently had some roof work, including the installation of drip edge. Could you tell me the purpose(s) of a roofing drip edge? Could you also tell me the proper location of a drip edge in relation to a gutter? (I fear that I may have had one installed incorrectly.)


Answer: Of all of the different types of flashing, drip edge flashing is the simplest. Drip edge flashing is commonly used at the rakes (gable end edges) and at the eaves (the leading edge of the roof where the gutters are installed). There are two basic types of drip edge. One type is known as “C”, this type of drip edge does not have an overhang. The other type is known as “Extended”. The Extended type has a hemmed overhang at the edge of the roof deck. Both types can be installed on the rakes or the eaves.
To prevent high wind and rain from entering at the rakes, the drip edge is installed on top of the underlayment. On the eaves the drip edge is installed under the underlayment, this allows any water that gets under the shingles to shed safely off the roof. If there are gutters on the eaves, the drip edge should be extended so water will flow directly into the gutters.

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