Roof flashing is any thin sheet of metal that professional roofers use to prevent water from reaching areas on the roof that are at risk of leaks. The thin sheet of metal is usually built to form a roof plane wherever the vertical surface of the roof meets a vertical object like a wall.
Roof flashing may also form a plane against other features like vents and chimneys. The structure ensures water runs down the flashing side so it doesn’t leak into the roof deck.
Types of Roof Flashing
Since many parts of the roof may likely need protection, there are different types of flashing for different areas around the roof.
There’s a method of roof flashing for areas like where the roof meets a wall, valleys where two roof slopes converge, roof protrusions, and roof edges.
Below is a list of the most notable roof flashing types.
· Base flashing
Base flashing is usually useful for roofs whose surface meets a vertical surface, such as a wall or parapet. Hence, the installation of base flashing is typically located at the seam where the roof surface meets the wall or parapet.
You will mostly find this style of roof flashing on roof chimneys. This is because chimneys usually require multiple flashing pieces to ensure watertight.
Besides, installing flashing around a chimney is very hard, so the best way to do it is to use the base flashing style.
· Step flashing
Step flashing is a rectangular type of flashing piece with a right-angled bend that allows it to fit into any angle where a sidewall meets a roof deck. As a result, it is mostly used for roof-to-wall flashing.
It is usually installed in layers alongside shingles to help prevent water from getting into the roof and wall. Ultimately, the step flashing keeps water on the roof’s surface and safely channels off the house.
· Valley flashing
This type of flashing is done around open valleys on a roof. It mostly forms a simple low line between the point where two roof decks meet. As a result, it mostly looks like a valley. This is why it is known as a valley type of flashing.
Installing the valley flashing is necessary if you have many areas on your roof where two roof decks meet. This is because those areas are one of the most common areas prone to water leakage.
· Continuous flashing
Continuous flashing is sometimes called “apron flashing” because it works like an apron. It is usually a long piece of metal that acts as an apron by collecting water residue and directing it down to the shingles
Though this flashing style is very effective, it has some drawbacks. The major drawback is that the effect of temperature can cause the metal flashing to expand or contract.
This tends to affect the effectiveness of the flashing. Fortunately, most continuous flashing materials now come with built-in expansion joints to help reduce the effect of expansion.
· Drip edge flashing
Drip edge flashing is usually installed around the edges of a roof to direct the water drops on the roof away from the shingles. It also prevents the water from running down into the fascia board.
· Counter flashing
Counter flashing is mostly used for roof flashing. It makes up a part of a two-piece system where it pairs with a base flashing to protect the top edge of the base flashing.
Roof Flashing Materials
There are three main materials used in the process of flashing a roof. These materials include:
· Aluminum:
Aluminum is a light-flashing material that’s easy to use. Though it is easy to install, you will need to coat it with concrete and masonry because plain aluminum degrades and corrodes quickly when it comes in contact with alkaline surfaces.
· Copper:
Copper is a strong material. It is very durable, and it has high malleability properties. The major drawback of copper is that it is very expensive and easily discolors.
· Steel:
Steel is a more popular material for metal flashing. It is aesthetically more pleasing, and it has higher malleability properties. It can also become corrosion-resistant when you galvanize it.
Roof Flashing Sealant Types
You will need to use a sealant when you bind roof flashing onto your roof. In most cases, roofing professionals use nails to seal roof flashing installations. They would use the nail on the roof plane or the vertical wall.
In cases where they apply nails to both the roof plane and vertical wall, the flashing quickly deforms due to the pressure from shifting brick or wood. Contrarily, when they apply the nail to the roof plane or vertical wall, the flashing stays in place longer.
Still, nail sealants are less durable compared to roofing cement sealants.
Roof Flashing Techniques
There are three different roof flashing techniques that are suitable for different roof areas. Since they are specific to different roof areas, you will find out that some types of flashing correlate with a specific technique.
- Step flashing: Step flashing is mostly used for areas where the roof meets a wall. In these types of areas, there’s a high possibility for water to flow down the wall and penetrate the shingles into the building. Step flashing helps ensure the water flows away from the wall. It is usually fixed between layers of shingles to ensure that water pours down each step and away from the roof.
- Counter-flashing: Counter-flashing is a method mostly used for chimneys. It also involves a two pieces flashing system. It involves a base flashing that occupies the bottom of the chimney. In addition, there’s a second piece, known as the counter-flashing. This second piece is always built into the masonry of the chimney. The typical arrangement is that the counter flashing lays over the base flashing to ensure water doesn’t go beyond the base flashing.
- Plumbing vent boot flashing: Vent flashing is a cylindrical type of flashing. It is built to fit around vents while the roof’s shingles are installed on top of its base. It uses its boot height to force water around the vent.
How To Install Flashing
If you intend to install flashing on your roof, you should ensure to do the right thing. Moreover, flashing techniques can be difficult to implement, so you must follow detailed guidelines if you intend to do it yourself.
Fortunately, you can leave much work to roofing professionals like Roofpro. You can rely on us for any of your roofing needs. Contact us, and we will let you know how we can help.