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There are different types of roof edges, notably drip edges and rake edges. Together, they make up an intricate roofing system. Every part of this system plays a different role in providing the homeowner with a secure roof. The edge plays the role of redirecting water droplets from the wooden portions of the roof and protecting the underpinnings of the roofing system.
Drip edges and rake edges are both metal sheets that are installed as part of the roofing system, and, as the “edge” in their name implies, they are placed at the edges of the roof. The primary difference between these two types of edges is where the edge is placed and the way the metal is angled in order to shed water away from the roof system.
But this brings on even more questions such as… “What type of edge should I look for in my roofing system?”, “How will I know what is right for me?” “Should I vie for both?” and “Is this information I will need to know or is this information primarily for my roofing installer?” All of these questions are answered below, so read on to find out more.
What’s the Difference Between Drip and Rake Edges?
Even though we use the word “roof” to refer to the covering of a building, it’s actually an entire roofing system, as we mentioned. The placement and use of drip edges and rake edges are imperative to a solid roof. Knowing the difference between the two, as well as how they’re used, is imperative to understanding how they function as part of the roofing system.
Location of the Edge
Drip edges are placed along with the eavestroughs of roofs. The eaves are the edges of the roof that hang over the face of the wall connected to the roof. Beneath these eaves are long, narrow open containers that water and other liquids can run through.
The purpose of the eavestrough is to be a vessel for rainwater to redirect and pour out instead of collecting in a pool on top of the roof and damaging the roof’s wooden components primarily. So, the drip edge attracts the rain droplets, snow, all types of precipitation into the eavestroughs, and away from the rest of the roof.
Rake edges, on the other hand, are placed along the ends of the gables of a house’s roof. The term “gable” used here refers to a triangular portion of the outside wall at the intersection of the roof and the wall, the roof pitches, in a gable-style roof (which is common in North America).
A gable style roof has two sloping sides and a gable at each end. You can picture the gable visually as being that portion of the triangular portion of the roof where the roofing comes up just a little from the rest of the roof and juts out, emphasizing the triangle.
With this said, it may seem a rake edge is particular to a gable-style roof and will not necessarily be used if a different type of roof is being installed. However, there are several other types of roofing systems that result in a triangular roof and that have rakes, so everything indicates that other types of roofs could use a rake edge as well. Contrarily, it is evident that a drip edge can be used in any condition.
Climate and Function of the Edge
The difference in the locations of the two edges also causes their functions to be slightly different from each other, and this becomes significant in different climates.
In a cold or temperate climate, snow and ice can build up in the eavestroughs when the weather is colder. Because this moisture is without the means to travel out and is blocked, it can travel backward up into the shingles of the roof and soak into the wood frame.
But, with a drip edge, the precipitation that may be potentially trapped is prevented from seeping into the wood by the barrier created by the edge.
In a climate that is windy, driving winds can force moisture to move sideways, under the shingles, and when this moisture soaks into the wood, it also leads to rotting wood in the roof.
Here, the rake edge blocks out moisture from being able to enter the shingles whilst attracting moisture away from the rest of the roofing and into the gutter of the roof as runoff.
Both of these edges may be used in a climate that is tropical because of the nature of heavy rains. Using both of the edges in conjunction with each other provides extra protection to the roofing system in this sort of climate.
On the outside of the roof, different materials are implemented to block against humidity entering the roof, but the edges of the roof remain vulnerable unless edges are used in addition.
Structure of the Edge
Both drip edges and rake edges can be formed with aluminum, galvanized steel, or copper. Aluminum is most common as it does not corrode, is lightweight yet durable, and can be sold in several different colors.
It is important that whichever of these materials the edge is composed of, it should not be a material which hinders water from running off the roof. It is also possible to get purchase an edge that has a protective coating on it in addition.
There are many different structures to edges, but most often, the difference in the structure of the two edge types occurs in the way the metal is bent and the resulting shape of that metal.
The metal of the drip edge trims and bends in to form a closure at the corner of the edge of the roof. It is corrugated. This bend in the metal locks the edge around the side of the house’s roof, covering up the shingles.
The drip edge is strong and can last longer than the rake edge. Because of this shape, the metal that has been prepared to use for a drip edge already is slightly pricier than that for a rake edge.
Secondly, as they are often placed directly above the underlayment of the roof and then covered by other roofing parts like the roofing sheets or tiles, drip edges may not be visible in the finished work, even though they are on the edges of the roof.
The metal of a rake edge, on the other hand, is bent at a 90-degree angle. It is bent that way so that it can lie properly on top of the gable of the roof. Different constructors, however, may apply different designs to their rake edges.
Some may have the rake edge divided into two portions: one that fits just on the inside of the gable’s edge and another that lies on the top forming the outside of the gable visibly. Another may have a simple one-piece rake edge that is fitted into the gable of the roof.
The rake edge is more likely to be directly visible because of the location it is fitted into, placed on the outside of the gable, as opposed to directly above the underlying of the roof.
Installing the Edges
Another place where these two types of edges differ is in how they are installed. “How they are installed” encompasses the stage at which they are installed, the location of the installation, and other details pertinent to the installation.
Regardless of whether it is drip edges or rake edges, the principle is that you consider where water will run off on your roof and enter unwarranted locations, and you prevent that occurrence from happening.
The drip edge should be installed at the eaves prior to the installation of the eave protective membrane. The reason why drip edges are installed in this location is to prevent water from getting under the drip edge into the wooden base of the roof.
The rake edge should be installed at the rakes above the underlay of the roof. This is done to seal the edges of the roof and to protect the roof’s components from wind-driven rain.
Installing the rake edge in this position closes off the edges of the underlayment specifically. This prevents water from entering the underlayment and then traveling into the wood decking of the roof, causing rot, amongst other problems.
The rake edges of the roof along the gables will be installed from the bottom edges of the roof to the top of the ridge, where they will come together to form a triangular shape. This will be clearly visible to passersby, unlike the drip edges.
When installing either of these edges, keep in mind that the edge needs to be nailed centered directly from the top at intervals of 8 to 10 inches apart. It is good to seek out professional help however
The distinction between drip edges and rake edges requires some attention to detail. There are many cases where rake edges are also called drip edges because both of these types of edges essentially play the role of attracting precipitation away from the roof and into the gutters and troughs on the edges of the roof.
Edges perform this function in order to prevent the prolonged exposure of the roof to this precipitation, which could potentially seep into the components of the roof and be absorbed by the wooden portions of the roof, which are not as durable as the rest of the roofing system. Keeping the wood protected is of key importance because once the wood is soaked in water, it will swell, rot, and then lose its stability.
The entire roofing system could become weakened by such an occurrence, and leaks could become commonplace. In the worst-case scenario, the whole roof could collapse into the building because it no longer has a structure. It is for this reason that drip edges are required by law in most of the United States of America and Canada as a safety precaution for roofs.
So, it is not that you need one or the other of these types of edges installed as part of your roofing system; rather, the two work in conjunction with each other. In many situations, both of these types of edges should be installed and not just one.
However, there may be some circumstances, examples of which are given in the aforementioned, where only one may be necessary. Seeking out professional advice concerning which edge will be correct for your roofing system is advisable. But, as the edges are part of the roofing system, these are concerns that might only become relevant if you are fixing current damage in your roof or installing a new roof into a building.
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Giovanni Valle is an architect, designer, internet entrepreneur, and the managing editor of various digital publications including BuilderSpace, Your Own Architect, and Interiors Place. He is the founder of BuilderSpace LLC.