Flashings are a vital part of any home exterior system by helping to direct the flow of water away from the interior to the exterior. Flashing comes in many types of materials from asphalt to metal and are mostly found in roof systems, though they can be found around other exterior openings like doors and windows.
In some instances it may be thought that the flashing is really not that necessary since there wont be much water in the area, like under the eaves. However, heavy and wind-blown rains can drive water into any crack or crevice in your home. Without the proper flashing leaks can be almost impossible to pinpoint and the damage can include rotted roof structures (decking, joists, trusses, eaves and soffits), ruined drywall, and damaged or ruined insulation.
There are many types of flashings available today just as there are many types of roofs. The more common types of flashings you may encounter in your home could be Rake, Gutter or Drip Edge, Valley, Step, Counter, Kickout, and Apron.
Rake flashing is found, as the name implies, on the rake (the gabled, diagonal edge) of the roof. It covers the top edge of the rake and is designed to direct water away from the rake and prevent it from flowing back towards the house or soffit area.
A lack of rake flashing can lead to water intrusion and costly repairs down the road. Below is a photo of a rake flashing. Notice the outward angle at the bottom of the flashing that is designed to direct water away from the house.
Gutter or Drip Edge flashing
Drip edge flashing is similar to rake flashing in design but it’s applied in different locations. Drip edge flashing is found along the horizontal edges of the roofline, most notably at the gutter hence the name Gutter flashing. Due to its cost effectiveness wood is the most common fascia board material.
Unfortunately wood is also prone to decay when wet. Drip edge flashing is designed to protect the fascia boards and keep moisture from damaging the materials. Like the drip edge flashing it to has an angled bottom to divert water away from the house.
Valley flashing is found where two angles of a room meet and form a valley. It’s designed to direct water away from the roof to a gutter system. Valley flashings are vital to the integrity of the roof since the valley is an area of concentrated water runoff.
Valleys come in two styles; open or closed. An open valley is where the shingles don’t meet together and you can see the valley flashing.
Open valleys are used when the shingle material doesn’t flex enough to “close” a roof valley (cedar shakes, synthetic shingles, metal, and some architectural asphalt shingles)
A closed valley is where the shingles meet and the valley flashing is hidden. Closed valleys are most common in your 3-tab or architectural asphalt shingles. The most common material used in valley flashing is steel, though copper can be used for a more aesthetic appearance in open valleys.
Drip edge flashing
Step flashing and Counter flashing
Step and counter flashing is used where the roof meets a vertical wall, around dormers, at skylights and around chimneys. Step flashing is a piece of metal that’s bent 90 degrees and goes up against the vertical wall and between the shingles. Counter flashing extends from the exterior and covers over the Step flashing. This keeps the water that is coming down the vertical service from getting between the shingles and damaging the roof structure.
Step and counter flashing is commonly made of aluminum due to its durability and easy application, but it can also be found in galvanized steel or copper. Step and Counter flashings are commonly seen where the roof meets the house and the flashing forms “steps” as it goes up the roof. While this is a common use, Step flashing can also be applied linearly to present a straight line instead of steps. This is often the case where the siding can cover the Step flashing and act as a counter flashing. The illustration below shows how the two flashings work together.
Step and Counter flashing
Kickout flashings, like all flashings, are intended to divert water to or from a specific area. These flashings are most commonly used in conjunction with gutters and are designed to divert water from the roof into the gutter, which is why they’re also called Diverter flashings. While most flashings allow water to naturally flow over them, Kickout flashings are designed to change the natural course of the water and redirect it to a specific point.
In many cases Kickout flashings are used where the roof meets the wall at the gutter. In this case the flashing will divert the water into the gutter. Often they’re used at a chimney chase or where there is no gutter present to prevent the water from flowing down the wall and creating unsightly flow staining.
Like Step flashing, Apron flashing is also shaped like an “L” and is used where the roof meets a vertical wall. However, Apron flashing is longer than Step flashing reaching lengths up to 14 feet and are comprised of one single component instead of multiple, overlapping components like Step flashing.
Another difference between Step and Apron is that Apron flashing goes over the shingles, not underneath like Step flashing. Sometimes, for aesthetic reasons, a row of shingle will be placed over the Apron flashing to hide it.
Like Step flashing, Apron flashing can be used with Counter flashing to create a more cohesive barrier.
Flashings are only one component of your whole house system, however they play a vital role in making sure your home stays dry during wet weather. It's important to be on the lookout for rust or any damage to a flashing as this can compromise its effectiveness and leave you with hefty repair bills.