The major purpose of any roof is to protect everything under it from the elements. For many, the only time they think about their roof is when it fails to keep the rain out. And while shingles nailed to the wood underlayment is what most homeowners think is their roof, a critical component of your roofing system that works behind the scenes to weatherproof your home is roof flashing.
Most roofs aren’t just flat, uninterrupted surfaces. They have ridges, valleys, and edges where two planes meet, along with openings for chimneys, vents, and skylights. These spots are particularly vulnerable because water naturally flows and pools there, increasing the risk of it seeping under the roof and into your home. That’s why roof flashing is so important—it plays a critical role in keeping your home protected from leaks.
What is Roof Flashing?
Roof flashing is a thin, durable material (usually metal like aluminum, copper, or steel) installed at roof joints, edges, and areas prone to leaks—like chimneys, vents, skylights, and valleys. Its job is simple but essential: direct water away from vulnerable areas and prevent it from seeping into your home.
After cutting the flashing into the desired shape, you place this material over the joint and under the shingle. You then secure the flashing to the roof with roofing staples or nails. Some exact methods of installation change depending on the joint(s) the flashing is securing.
Why is Roof Flashing Important?
Without proper flashing, even the most high-quality roofing materials can struggle to hold up against heavy rain, snow, and ice. Flashing creates a watertight seal at tricky spots on your roof, adding an extra layer of protection where leaks are most likely to happen.
Common Types of Roof Flashing
- Step Flashing: Perfect for areas where the roof meets a vertical wall, like chimneys or dormers.
- Drip Edge Flashing: Installed along roof edges to guide water into the gutters.
- Valley Flashing: Protects the intersections where two roof planes meet.
- Counter Flashing: Paired with step flashing for extra reinforcement around chimneys.
Typical Locations of Roof Flashing
You should install flashing anywhere there is a break in the roof into which water might seep. Few roofs can get away with only flashing where two roofing planes meet. Many roofs have multiple gaps due to the home’s chimney, kitchen vent, or the occasional skylight.
Here are common locations for flashing, and how the flashing installation differs from location to location.
Chimney:
The chimney uses two types of flashing methods. On the front and back where it is level with the roof it uses continuous flashing, but on the sides it uses the step method. L-shaped sections of flashing as wide as the length of shingles are layered overlapping beneath the shingles with the angle of the flashing resting against the chimney, forming “steps” up the side.
Valley or Ridge:
Whenever two major planes meet, such as the ridgeline of the roof or a valley from a porch extension, they form a long line joint. This joint needs to be capped. These flashings are always underneath the shingle.
Vents:
The venting pipes tend to be circular in nature, which would defeat the traditional flashing. Most vents come with their own flashing cover. The contractor installs this cover over the vent and then covers it with shingles cut to fit.
Skylights and Dormers:
With these large box designs, the front is a continuous flashing. Dormers have step flashing on sides. Skylights usually have specially cut flashing for the corners to provide additional durability from leaks.
Sheathing: Where the roof ends and paint begins is a last line of flashing, a cusp going around the perimeter of the roof and preventing water from seeping into the wood of the overhang.
The Proper Way to Install Flashing
Properly installing roof flashing is all about precision and attention to detail. Here’s a breakdown of how to properly install roof flashing:
- Choose the Right Material: Select the appropriate type of flashing for each area (step flashing for roof-wall joints, drip edge for eaves, etc.).
- Proper Overlap: Flashing should overlap the roofing material to ensure a watertight seal, with no gaps for water to slip through.
- Secure Fastening: Use roofing nails or screws to fasten the flashing tightly, ensuring it lies flat and stays in place.
- Seal Edges: Apply high-quality roofing sealant around the edges of the flashing for added protection against leaks.
- Extra Protection for Vulnerable Areas: For features like chimneys and skylights, use counter flashing to provide an additional layer of defense.
This step-by-step approach will ensure your roof flashing is installed correctly to protect your home from water damage.
Maintenance Matters
Flashing is tough, but it’s not invincible. Over time, exposure to harsh weather can cause it to corrode, loosen, or crack. That’s why regular roof inspections are key to catching potential issues early. Repairing or replacing damaged flashing is much easier (and cheaper) than dealing with water damage inside your home!
Invest in Your Roof’s Future
If you’re planning a new roof installation or repairs, don’t overlook the importance of quality roof flashing. A little extra investment now can save you from costly headaches down the road.
Need professional help with your roof flashing or an inspection? Contact us today to ensure your home stays safe, secure, and weatherproof!