The term “drip edge” refers to the metal flashing or water-resistant barrier that is placed at the edge of a roof and that has an overhang from the roofline. It shields the fascia board from water seeping in from the top, underneath the shingles, and into your house. Drip edging aids in preventing capillary action, which takes place when moisture flows off the roof surface, flows underneath the gutter and behind the shingle edge, rotting the fascia boards. In cold areas, it also prevents ice dams on rooftops by draining precipitation before it can freeze.
This metal flashing is installed by the roofing contractor before they install the roof covering material. Aluminum, copper, and galvanized steel are a few examples of non-corroding, non-porous metals that are used to create metal drip edges. Alternatively, some flashing is made of resilient plastic, vinyl, and fiberglass.
The small, integrated lip that is present on many roof gutters is inadequate to provide the protection that the edge of the roof requires. Modern building standards, roof shingle manufacturer guidelines and modern building codes in most jurisdictions typically call for the drip edge flashing to extend up the roof deck a minimum of 2 inches. The lip of the typical gutter extends up the roof deck less than one inch. The lip on the gutter is simply not long enough to provide adequate protection at the edge of the roof and dedicated flashing needs to be installed.
It is possible to add drip edge flashing to a roof where it was not installed initially. We recommend having a qualified roofing contractor install the drip flashing. Installing this flashing after the roof shingles are in place can be difficult and often requires working at heights and from a ladder. Additionally, if you don’t properly install the drip edge flashing, water may not flow into the gutters as intended. This often results in water damage and wood decay. Your soffit and fascia boards can be destroyed as a result. Badly fitted drip flashing could cause damage that will require expensive future repairs.
When adding drip edge flashing, the soffit and fascia should be inspected to ensure that they are in good shape. The installation of a drip edge will only conceal any rotten wood that is present on your fascia or soffit – you should fix the damage before installing the flashing.
Shingles should not have an excessive overlap of the flashing. No more than ¾ inches of the shingle should extend past the flashing. This helps keep the shingles from blowing off the roof during strong wind events.
You can find more information about this topic in the following video: