What is roof flashing?
Roof flashing is key to a secure and weatherproof home. But what exactly is it, and why is roof flashing important?
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Your roof is one of the most important components of your home, and roof flashing safeguards your roof's integrity. But what is roof flashing, and why is it so important?
Essentially, roof flashing is thin metal sheeting that can be bent into shape to fit a joint. It is usually made from steel, copper or aluminum, and it provides a watertight seal to prevent liquids from seeping through into your home.
Most roofs include penetrable sections where two types of material meet, such as chimneys, skylights or vents. These roof areas are susceptible to water infiltration, and flashing reinforces these vulnerable areas, diverting the flow of water away and keeping moisture out.
Roof flashing is usually sealed in place with stitching screws, silicone or mastic lapping tape (an adhesive tape used to seal joints in metals and plastics). It can be resistant to corrosion and durable enough to withstand exposure to the elements.
Why is roof flashing important?
A shingle roof with roof flashing that is in good condition
Roof flashing protects your roof in two main ways. It is used as a sealant, plugging any small gaps left at joints or roof features. Due to its malleable nature, roof flashing can be molded to fill any crevices where different materials meet, to stop water penetration.
Secondly, roof flashing is designed to encourage the flow of water down the roof and into gutters, allowing it to harmlessly roll away, without pooling.
Where roof shingles butt up against a joint (near a chimney, for example), leaks are likely to develop over time. However, with roof flashing installed (if fitted correctly), these areas will remain leak-free for as long as the flashing lasts.
Different types of roof flashing
A shingle roof with a brick chimney and roof flashing
The different types of flashing are named according to the roof area they protect.
Although many different forms of roof flashing exist, certain types are far more common than others, according to Bill Ragan Roofing Company , one of the best roofers in Nashville , Tenn. The company identifies four common forms of roof flashing: Apron Flashing, Step Flashing, Counter Flashing and Roof Valley Flashing.
Apron Flashing (otherwise known as continuous or base flashing) is primarily used to waterproof any area where the roof meets a vertical wall. It is a single, long piece of flashing that carries water down the roof shingles.
Step Flashing involves several pieces of rectangular flashing bent at 90-degree angles. It is used at the meeting point between your roof and any wall. This technique consists of layering multiple pieces of flashing in line with roof shingles to encourage water flow away from walls.
Counter Flashing is often used to bolster Apron Flashing. It is installed on top of the base flashing as a second line of defense to impede water infiltration.
As its name suggests, roof valley flashing is designed to provide a waterproof seal that runs the length of your roof valley. A roof valley is where two roof facets intersect on a slope, and they can be open or closed. It prevents water from seeping inside the roof valley and directs it down the slope into the gutter.
In some cases, several types of flashing will be used, although this tends to be for more specific feature installations, such as roof windows.
Signs you need new roof flashing
Warped metal flashing seen on the side of a brick chimney
According to Lyons Roofing, a roofer based in Phoenix, these are the following signs your roof flashing needs to be replaced.
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Rust and corrosion:Metal, one of the most common materials used for roof flashing, can corrode over time due to water.
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Cracked or broken flashing:Strong storms with high winds or hail can damage roof flashing, causing it to crack or break.
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Water stains:Discoloration on ceilings from water stains can indicate the flashing is failing.
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Leaks when it's raining:Roof flashing directs water away from vulnerable areas of your roof, so leaks during storms can indicate damage.
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Loose or warped flashing:Flashing that is warped or moves is not properly keeping things watertight.
If you suspect that your roof flashing may need to be replaced, call a licensed roofing contractor for a roof inspection. Many roofers offer free inspections, though some fees may apply. Check out our guide to roof inspection costs so you know what to expect in your area. This type of evaluation is best left to the professionals, as it likely requires repairs.
How much does roof flashing cost?
A roofer uses a hammer and a nail to install copper edge flashing during a residential roof replacement
The cost of installing or repairing roof flashing can vary considerably and depends on the size of your roof, the materials used and the areas where you want your flashing installed, repaired or strengthened.
The average cost of roof flashing repairs is between $200 and $500, according to Angi , an online home services provider platform. This excludes chimney flashing repairs, which Angi says can be as high as $2,000 if you choose to replace the roof flashing entirely instead of repairing the existing flashing.
The materials used for roof flashing affect the overall cost, according to Phoenix-based roofing specialists Diversified Roofing . For instance, the lifespan of copper flashing can be 20 to 35 years, while galvanized steel flashing may only last for 15 to 20 years.
Although durable, roof flashing has a finite lifespan, and constant exposure to the elements will break it down. The advantage of paying for a more durable material upfront is that it will likely last for much longer and won't need to be replaced quite as soon.
Roof flashing is typically priced per linear foot, with steel being the cheapest material and copper among the most expensive. Depending on the materials, the average cost of roof flashing will range between $15 and $25 per linear foot, according to Melo Roofing , a roofing company located in Syracuse, N.Y.
Once the materials have been purchased, Melo Roofing estimates the average cost of roof flashing jobs to be between $200 to $500, which tallies with the average costs outlined by Angi. Not all roofing companies offer free estimates, so quotes could also be an extra expense.
If your roof flashing requires major repair work, this can bump up the cost considerably, with prices ranging from $800 to $1000, according to Bark.com , a local service aggregator. However, you might be able to negotiate this with your roofing contractor to secure concessions for larger jobs.
Roof flashing is essential for a secure home
Prevention is better than cure, which is why effective roof flashing is so important. Damaged or compromised roof flashing can lead to all kinds of issues with your roofing and may end up costing you a small fortune in expensive repairs. Ensuring your roof is outfitted with the right kind of flashing results in a watertight seal that will protect your home year-round.
