Drip edge as it is commonly referred to, is a roof flashing detail that is recommended to be used when installing a new sloping roof assembly.
In the category of drip edge flashing there are fundamentally four types or variations of the product.
One type of drip edge so to speak is named “eaves starter strip”. This profile of metal is constructed so that about three inches of material is applied to the bottom roof eaves edge, and has about one inch of the profile that extends down over the fascia board.
Such material has a sharp outward lip bent at the intersecting bend of the slope and the fascia. This is designed to hold the shingles up over the leading edge of the roof. Such materials are widely available
through roofing suppliers, and are fabricated using light gauge aluminum or galvanized metal.
This type of metal profile; as with all drip edge flashings, is designed to cover the void between where the roof sheeting ends, and the top of the fascia board intersect. Drip edge flashings also serve to protect from animal or bird intrusion at the roof eaves edge. Drip edge can also help direct shedding roof water into the gutter system.
The best drip edge for shedding water into a gutter is fabricated with a larger face profile on the fascia side. Ideally, it is also formed to have a double hemmed safety edge at the bottom of the profile. This eliminates sharp edges if one must clean out the gutter system at a future date.
The smaller faced drip edge profile known as “eaves starter” is best used when existing gutters have screen toppers. Such screening inhibits the drip edge metal from entering into the gutter itself.
Large faced drip edge requires custom bending by a sheet metal mechanic, who will fabricate such metal to coincide with the pitch of the roof, and the camber of the guttering. As a result, a large face is more expensive to produce and install than small girth eaves starter metal.
Another variation of drip edge metal is termed “rake edge flashing”. Such metal is installed at gable ends and rake edges of sloping roofs. Its purpose is to envelope underlayment at such locations as well as increase resistance to wind tear-off for related roof coverings.
In the case of standing seam metal roofs, both the drip edge and the rake edge flashings serve as a hook strip for which the metal roof panels hook onto. They represent a key component in the installation of all metal panel roofing systems.
Another application for drip edge flashing is in the installation of flat roof or low slope roof assemblies.
On flat roofs, drip edge is used on the open edges of flat roofs that shed into an eaves-trough /gutter.
Drip edge is among the simplest types of metal to form as essentially it has an “L” profile. The process of making drip edge begins by marking the desired overall width of the metal pieces required for the application. Marking is done using a metal punch and hammer.
Once the flat stock sheet metal has been marked to size; it is fed into a metal slitter machine that sheers the metal into the desired size of strips.
The metal mechanic will then bend the metal on a metal brake; once having marked the pieces for all bending locations. The hem portion will be bent over, then this particular seam will be flattened, and then an outward bend will be created to form a “drip lip”.
The piece will then be repositioned in the brake to allow for the centre bend on the drip edge. One side in the bend will mimic the sloping roof pitch, with the opposing face of the metal designed to mimic the fascia profile.
When doing decorative copper or metal work; the drip edge flashings may also be fabricates with slip locks in order to retain a tight continuous appearance in the adjoining pieces of drip edge, as well as allowing for expansion and contraction over a long run of metal.
The process of slip-locking drip edge, or any adjoining metal for that matter, involves creating a “male” and “female” end to each piece of metal. By folding the metal on the end profile to create a pocket, for which the open ended, adjoining piece of metal may be received. This also creates a more water resistant joint.
The process of installing drip edge is relatively simple with a few details in mind.
For example if there are existing gutters on a building; one must systematically remove the spikes and furls (or screws and gutter brackets as the case may be) in a strategic manner before installing the drip edge piece itself. This is more easily accomplished on a one storey, shallow pitched roof as opposed to three stories on a steeper roof pitch.
Drip edge flashings can be installed in two ways as it concerns a relationship to the roofing underlayment materials. At the bottom roof eave edge of a sloping roof; it is most common today to install an ice and water barrier membrane.
After placing the membrane along the base of the roof, and folding it down over the fascia board two inches; the drip edge metal can then be installed over top and nailed at eight to twelve inch intervals.
The process then involves placing a strip of the ice and water membrane over the nailed portion of the drip edge metal. The process is known as “enveloping the drip edge”. This detail is a commonly requested specification by engineers and represents a solid barrier against ingress of ice and snow which may freeze back up from the gutters in extreme winter conditions.
A commonly accepted approach is to simply install the drip edge at the base of a bare wood roof slope, and then apply the ice and water barrier membrane on top of the drip edge and up the slope.
It is generally accepted that drip edge is a good idea to be installed on roofs which have an 8/12 pitch or lower. Installing drip edge on steeper pitches can also provide benefits but may not be absolutely necessary if for example the fascia board has been cladded over with aluminum.
The most common applications of drip edge are completed with pre-painted galvanized steel and copper as the premium choice for certain types of roofing such as cedar or slate.
In summary, drip edge metal is one component of an ice damming resistant system, helps impede vermon intrusion, and helps direct water into a building s gutter system.
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