The flashing on your roof is a critical component of weatherproofing since it protects the roof’s most susceptible spots from the elements. But different spots and different types of roofing may use completely different types of flashing.
Here are some of the different types of flashing that can be found on a typical roof and what they do.
Asphalt shingles require a type of flashing called step flashing in some areas. It’s so called because it’s made of small pieces of flashing inserted stepwise between each row of shingles along an edge where the roof meets a vertical wall. This can be a tricky installation, especially if the wall isn’t completely flat.
One common problem is when the roofing contractor uses one long piece of metal (continuous flashing) rather than the correct step flashing installation. This may be due to ignorance or simply because step flashing takes more work, skill, and finesse to install.
Continuous flashing may be acceptable practice in a few situations, but it’s less likely to protect your roof from all moisture intrusion.
Anything that sticks up through your roof (called a roof penetration) needs flashing since it comes with a hole in the roof and that hole needs to be protected from moisture and pest intrusion. Vents such as kitchen, bathroom, and plumbing vents are common roof penetration elements.
Sometimes metal flashings are used for these vent pipes, whereas other times a vent boot is used. Either way, the setup is designed to allow venting through the pipe while avoiding water damage. But the vent flashing has to be installed correctly to do this job. If the shingles don’t overlap the flashing on the uphill side or do overlap it on the downhill side, there’s a problem.
Drip Edge Flashing
You may have heard that metal roofs don’t need drip flashing. And it’s true that the edge of a metal roofing panel can provide a well-defined edge for water to drip from so it won’t wick up under the eaves into the roof deck material. However, that’s not the only function a drip edge has.
Drip edge flashing helps to shield the underside of the eaves from the splashes and high humidity that occur directly over a rain gutter, as well as from wind-blown rain getting up under the roof. And if the eaves have a builder’s gap, drip edge flashing is also needed to keep pests and moist air from getting in the gap and wreaking havoc in your attic.
Yes, a metal roof will likely survive a lack of drip edge flashing better than a shingle roof would. However, for the best protection against water damage and pests, you’ll want a drip edge flashing with either a shingle roof or a metal roof.
Chimney flashing is a system of two different layers of metal flashing pieces. The bottom layer at the front of the chimney is called the base flashing, and step flashing is installed along the sides. You can also use a special piece of flashing called a chimney saddle or saddle flashing along the uphill side of the chimney (if there is an uphill side).
The top overlapping layer is called the cap flashing. The cap flashing has to be set into the mortar between the chimney bricks to prevent water from sliding behind the flashing. It then requires a little caulk along the top edge to provide additional sealing. However, it shouldn’t have large patches of caulk or tar; those may be a sign of an amateur repair attempt.
For all these types of flashing and any others your roof might require, you need an expert roofing contractor to install them correctly. Get in touch today and R. L. Hayes can help you with all your roofing and flashing needs.