5 Types of Drip Edges on Metal Flashings
Drip edge can be found on many metal flashings and components that are installed on your roof system, including:
- gutter apron
- rake edge flashing
- gravel stop
- chimney caps
Its important to note that gutter apron and rake metal are often referred to as ‘drip edge.’ This isn’t necessarily incorrect, but it is generic or slang term at best. The drip edge is the part of the metal component that has an outward projecting lower edge that is intended to divert dripping water away from other building materials such as wood siding, fascia boards, or masonry. Ideally, any water that is shed from a roof system should be diverted to a gutter and downspout and be carried into a storm sewer.
Perimeter metal is an important component on a roof system as the edge of the roof is most vulnerable to damage caused by wind uplift. It also provides a termination point for the edge of the roof system. Here are descriptions and examples of how various types of metal flashings incorporate a drip edge.
Gutter apron is often the first metal component installed on a roof system. It is applied directly to the sheathing and beneath the underlayment. Any water that infiltrates the roof can be shed by the underlayment and then over the gutter apron. The gutter apron also protects the gap between the fascia board and roof sheathing, preventing insects, animals, and water from entering the eaves and attic space. The drip edge on the lower portion of the gutter apron helps to direct water into the gutter instead of running behind it down the fascia board.
Rake edge flashings work in a similar manner as gutter apron but protect the rake frieze boards instead of the fascia boards. Since gutters are not installed on rakes, the drip edge on the rake metal prevents water from draining down the trim boards, siding, and/or masonry.
Gravel stop is a type of perimeter edge metal that is used to terminate a roof membrane at the perimeter of a low sloped roof system. The gravel stop contains a flange that prevents loose gravel or ballast from washing off a roof. The drip edge on gravel stop works in a similar manner as rake edge flashing, protecting the materials on the side of a building from water runoff.
Chimney caps or chase covers are typically fabricated from sheet metal as pictured below. The caps are tapered so that water has positive drainage to the edge of the caps. This drainage system will prevent ponding water on the cap and ensure longevity. The drip edge on the sides of the caps divert the draining water onto the roof system instead of down the sides of the chimney where it can be problematic.
Coping is found on parapet walls and is designed to protect the top of the wall from water intrusion and terminate the roof membrane. Coping actually has 2 separate drip edges, one on the exterior side of the wall and one on the interior (or roof side). The coping contains a slight taper to ensure water drains back onto the roof and eventually to roof drains or gutters.
It is not a good idea to install any of these flashing components without a drip edge. The drip edge promotes proper drainage and protects other building materials. Installing metal without a drip edge will lead to building envelope system failures and water infiltration.
For more information on edge metal or drip edge, contact us.