Roof Flashing Failures in Michigan: What Goes Wrong & Why
By:
NEXT Exteriors
Published:
February 19, 2026
Reading Time:
12 minutes
Here's something most homeowners don't know: the shingles aren't what keep water out of your house. The flashing is.
After 35 years of Detroit roofing services, we've seen thousands of leaks. And the vast majority — probably 80% — start at one of three places: chimneys, valleys, or wall intersections. Not because the shingles failed. Because the flashing did.
In Michigan, where we get freeze-thaw cycles from November through April, ice dams in January, and summer storms that drop two inches of rain in an hour, flashing takes a beating. It expands, contracts, rusts, lifts, and eventually fails. And when it does, water finds its way into your attic, your walls, and your ceilings.
This isn't a "maybe someday" problem. Once flashing starts leaking, it's already causing damage. The longer you wait, the more expensive the fix becomes — because now you're not just replacing flashing, you're replacing rotted decking, soaked insulation, and water-stained drywall.
Let's walk through what flashing actually is, why these three areas are so vulnerable, and what proper installation looks like. Because if you're getting a roof replaced or repaired in Sterling Heights, Troy, or anywhere in Southeast Michigan, you need to know what to look for.
What Is Roof Flashing (And Why It Matters More Than Shingles)
Flashing is thin metal — usually aluminum, galvanized steel, or copper — that's installed wherever two different surfaces meet on your roof. Its job is simple: direct water away from vulnerable seams and onto the shingles, where it can run off harmlessly.
Shingles are designed to shed water when it's flowing downhill. But at chimneys, valleys, and walls, water hits a barrier or changes direction. That's where flashing takes over.
Think of it this way: shingles are your roof's raincoat. Flashing is the seal around the collar, cuffs, and zipper. If the seal fails, it doesn't matter how good the raincoat is — you're getting wet.
Here's what most homeowners miss: flashing isn't just slapped on top of the shingles. Proper flashing is integrated into the roof system. It goes under shingles in some places, over them in others, and gets layered in a specific sequence so water can't work its way backward. When a roofer cuts corners on flashing — and plenty do — you won't see the problem until it rains hard or an ice dam forms. By then, the damage is already happening.
Chimney Flashing: The Most Common Leak Point
If there's one place on a roof that's guaranteed to leak eventually, it's the chimney. Not because chimneys are inherently bad — but because chimney flashing is complicated, and most roofers don't do it right.
A properly flashed chimney has three components:
Step flashing: Individual L-shaped pieces of metal that weave between the shingles and run up the side of the chimney. Each piece overlaps the one below it, creating a waterproof barrier.
Counter flashing: Metal that's embedded into the chimney mortar joints and laps over the step flashing. This prevents water from running down the brick and behind the flashing.
Cricket (or saddle): A small peaked structure installed on the uphill side of the chimney to divert water around it instead of letting it pool behind the chimney.
Here's where things go wrong: many roofers skip the cricket entirely. They'll slap some step flashing on the sides, smear a bead of caulk where the metal meets the brick, and call it done. That works for a year or two. Then the caulk cracks, water seeps behind the flashing, and you've got a leak.
In Michigan, the problem is worse because of ice dams. When snow melts and refreezes at the roof edge, it creates a dam that forces water to back up under the shingles. If your chimney doesn't have a cricket, that water pools behind the chimney and has nowhere to go except under the flashing and into your attic.
Why Michigan chimneys leak more than anywhere else: Our freeze-thaw cycles cause brick mortar to crack and deteriorate faster. When counter flashing is embedded in deteriorating mortar, it loosens and pulls away from the chimney. Water runs straight down the gap and behind the step flashing. If you've got an older brick Colonial in Grosse Pointe or Rochester Hills, this is something to watch closely.
Signs of chimney flashing failure include water stains on the ceiling near the chimney, rust streaks on the metal flashing, or visible gaps between the flashing and the brick. If you see any of these, don't wait. The longer water gets in, the more rot spreads through your roof decking.
Valley Flashing: Where Two Roof Planes Meet
Valleys are the V-shaped channels where two roof slopes meet. They're designed to funnel water off the roof, which means they handle more water flow than any other part of your roof. That makes them a high-risk area for leaks.
There are three main types of valley construction:
Open valley: Metal flashing runs down the center of the valley, and shingles are cut back to expose the metal. Water flows directly on the metal.
Closed valley: Shingles from both roof planes overlap in the center, with flashing underneath. The shingles shed the water, and the flashing acts as a backup.
Woven valley: Shingles from both sides are woven together in an alternating pattern. This method is less common now and not recommended for architectural shingles.
Open valleys are the gold standard for durability, especially in Michigan. Metal doesn't rot, tear, or deteriorate like shingles do. When we install exterior services in Detroit, we use 24-gauge galvanized steel or aluminum for valley flashing — materials that can handle decades of freeze-thaw cycles and heavy water flow.
The most common valley flashing mistakes we see:
No underlayment: Some roofers lay flashing directly on the roof deck without an ice-and-water barrier underneath. That's a recipe for leaks.
Improper overlap: Valley flashing should overlap at seams by at least 6 inches, with the uphill piece on top. If it's reversed, water flows under the seam.
Wrong material: Using standard roofing felt instead of peel-and-stick ice-and-water barrier in the valley. Felt absorbs water; ice-and-water barrier seals around nail penetrations.
Shingles cut too close: In open valleys, shingles should be cut back at least 2 inches from the valley centerline. If they're too close, water can wick under the shingles.
Ice dams are particularly brutal on valleys. When water backs up behind a dam, it pools in the valley and finds any weak point in the flashing. If the flashing wasn't installed correctly in the first place, that's where the leak starts.
Wall Intersections: The Hidden Failure Zone
Wall intersections are where a vertical wall meets a sloped roof — think dormers, second-story additions, or where your house steps down from two stories to one. These are some of the trickiest areas to flash correctly, and they're where we see the most hidden damage.
The problem is that water running down the wall hits the roof and needs to be directed onto the shingles, not behind the siding. That requires a specific type of flashing called step flashing, which is installed in a stair-step pattern between the shingles and up the wall. Each piece overlaps the one below it, and the siding overlaps the flashing.
Here's where things go sideways: many roofers use continuous flashing instead of step flashing. Continuous flashing is a single long piece of metal bent at a 90-degree angle. It's faster to install, but it doesn't work. When the roof expands and contracts with temperature changes, continuous flashing buckles and pulls away from the wall. Water gets behind it.
The other critical component is kickout flashing (also called a diverter). This is a small piece of flashing installed at the bottom of a roof-to-wall intersection that kicks water away from the wall and onto the roof. Without it, water runs straight down the wall and behind the siding. We've torn off siding on homes in Shelby Township and Clinton Township where the entire wall sheathing was rotted because there was no kickout flashing.
Why this matters if you're getting new siding: When we install house siding in Detroit, we always inspect the roof-to-wall flashing. If it's missing or damaged, we fix it before the new siding goes on. Otherwise, you're covering up a leak that's going to destroy your new siding from behind.
Signs of wall intersection flashing failure include water stains on interior walls near dormers, peeling paint on exterior walls below the roofline, or soft spots in the siding. If you've got a second-story addition or a complex roofline with multiple wall intersections, this is something to check carefully.
Why Flashing Fails in Michigan (It's Not Just Age)
Flashing doesn't just wear out from age. It fails because of specific stresses that are particularly brutal in Michigan's climate. Here's what actually causes flashing to fail:
Freeze-Thaw Cycles
Michigan gets an average of 60 to 80 freeze-thaw cycles per winter. That means the temperature crosses the freezing point 60 to 80 times between November and April. Every time it does, metal expands and contracts, mortar cracks, and sealant pulls away from surfaces.
Flashing that's embedded in chimney mortar or tucked under siding experiences this stress constantly. Over time, the metal fatigues, fasteners loosen, and gaps open up. That's why 15-year-old flashing in Michigan looks worse than 25-year-old flashing in Georgia.
Ice Dams
Ice dams form when heat escaping from your attic melts snow on the roof. The water runs down to the eaves, refreezes, and creates a dam. Water backs up behind the dam and sits under the shingles, where it finds any gap in the flashing.
The fix isn't better flashing — it's better insulation services in Southeast Michigan. If your attic is properly insulated and ventilated, your roof stays cold, snow doesn't melt, and ice dams don't form. But if the insulation is inadequate, no amount of flashing will keep water out once an ice dam forms.
Poor Original Installation
This is the #1 cause of flashing failure, and it's not even close. Most flashing problems we see aren't from age or weather — they're from roofers who didn't know what they were doing or didn't care.
Common installation mistakes include:
Using roofing nails instead of corrosion-resistant fasteners
Skipping the ice-and-water barrier under flashing
Not overlapping flashing pieces correctly
Relying on caulk instead of proper mechanical laps
Installing flashing over instead of under shingles
Not extending flashing far enough up walls or chimneys
If your roof was installed by the lowest bidder who showed up in a pickup truck with no company name, there's a good chance the flashing is wrong. It might not leak for a few years, but it will eventually.
Sealant Deterioration
Sealant (caulk) should be a backup, not the primary waterproofing method. But many roofers use it as a Band-Aid to cover up gaps in poorly installed flashing.
Here's the problem: even the best polyurethane sealant only lasts 5 to 10 years in Michigan's UV exposure and temperature swings. When it cracks and pulls away, water gets in. If the flashing underneath wasn't installed correctly, you've got a leak.
We use sealant where it's appropriate — at certain chimney joints, for example — but we never rely on it as the sole line of defense. Proper flashing works mechanically, with overlapping metal layers that shed water by design, not by adhesive.
Signs Your Flashing Is Failing
Most homeowners don't realize they have a flashing problem until water is dripping through the ceiling. But there are early warning signs you can spot from the ground or the attic. Here's what to look for:
Interior Water Stains
Brown or yellow stains on ceilings or walls near chimneys, dormers, or exterior walls are the most obvious sign. If the stain is directly below a chimney or near a roof valley, flashing is the likely culprit.
Don't assume the leak is fixed just because the stain isn't getting bigger. Water might be running down a rafter or wall stud and dripping somewhere you can't see. By the time you notice the stain, there's already rot in the framing.
Visible Rust or Corrosion
If you can see the flashing from the ground (use binoculars), look for rust streaks, orange discoloration, or holes in the metal. Galvanized steel flashing eventually rusts through, especially at nail holes and cut edges. Aluminum doesn't rust, but it corrodes and develops white powdery deposits.
Once rust starts, it accelerates. A small rust spot becomes a hole in a year or two.
Lifted or Bent Flashing Edges
Flashing should lie flat against the roof and wall surfaces. If you see edges sticking up, gaps between the flashing and the brick, or metal that's bent or buckled, that's a failure point.
This is especially common on chimney counter flashing that's pulled out of deteriorating mortar joints.
Cracked or Missing Sealant
Check the caulk joints around chimney flashing and where metal meets brick or siding. If the sealant is cracked, hard, or missing entirely, water can get in.
Again, sealant should be a backup, not the primary defense. But if it's failed and the flashing underneath wasn't installed correctly, you've got a problem.
Water Marks on Siding
Look at the siding below roof-to-wall intersections. If you see water stains, algae growth, or paint damage, water is running down the wall behind the flashing. That means the kickout flashing is missing or the step flashing is installed wrong.
This is a big deal if you're planning to get new window replacement in Detroit or new siding. Fix the flashing first, or you're just covering up a leak that will destroy your new materials from behind.
What Proper Flashing Installation Looks Like
When we replace a roof or repair flashing, here's how we do it — and what you should expect from any contractor you hire.
Materials We Use
We use corrosion-resistant materials that are appropriate for Michigan's climate:
Aluminum flashing: Lightweight, doesn't rust, and lasts 30+ years. We use this for most step flashing and wall intersections.
Galvanized steel: Heavier and more rigid than aluminum, good for valley flashing and areas that need structural strength. We use 24-gauge or heavier.
Copper flashing: Premium option for chimneys and high-visibility areas. Lasts 50+ years and develops a natural patina. More expensive, but worth it on historic homes or high-end projects.
Ice-and-water barrier: Peel-and-stick rubberized underlayment that seals around nail penetrations. We use this under all flashing in valleys, at eaves, and around chimneys.
We don't use roofing nails to fasten flashing. We use corrosion-resistant screws or blind rivets that won't rust through and create leak points.
Chimney Flashing Process
Here's how we flash a chimney correctly:
Install ice-and-water barrier around the base of the chimney, extending at least 6 inches up the sides and back.
Install step flashing on the sides of the chimney, weaving each piece between shingle courses. Each piece overlaps the one below by at least 3 inches.
Cut reglets into the mortar joints (or use existing ones if they're in good condition) and embed counter flashing. The counter flashing laps over the step flashing by at least 4 inches.
Build a cricket on the uphill side of the chimney if it's wider than 30 inches (required by Michigan building code). The cricket diverts water around the chimney instead of letting it pool.
Seal the counter flashing into the mortar joints with polyurethane sealant rated for exterior use.
If the chimney mortar is deteriorating, we recommend repointing (re-mortaring) the joints before installing new flashing. Otherwise, the counter flashing will just pull out again in a few years.
Valley Flashing Process
For open valley installation:
Install ice-and-water barrier the full length of the valley, extending at least 18 inches on each side of the centerline.
Install metal valley flashing over the ice-and-water barrier. Overlap seams by at least 6 inches with the uphill piece on top.
Fasten the flashing along the outer edges only, not down the center. This allows the metal to expand and contract without buckling.
Install shingles and cut them back at least 2 inches from the valley centerline. Some manufacturers require 3 inches.
Apply a bead of roofing cement under the cut edge of each shingle to seal it to the valley flashing.
We don't weave valleys with architectural shingles. The shingles are too thick and stiff to weave properly, and it creates a weak point in the valley.
Wall Intersection Flashing Process
For roof-to-wall intersections:
Install ice-and-water barrier up the wall at least 6 inches and out onto the roof at least 12 inches.
Install step flashing between each shingle course, extending at least 4 inches up the wall and 4 inches out onto the roof.
Install kickout flashing at the bottom of the intersection to divert water away from the wall and onto the roof.
Install siding over the flashing, lapping at least 2 inches over the flashing. The siding should never be in direct contact with the roof.
If the wall has existing siding, we remove the bottom few courses, install the flashing, and reinstall the siding. If the siding is damaged or we're doing a full exterior painting project in Southeast Michigan, we replace it.
Cost Reality: Flashing Repair vs. Full Roof Replacement
Here's what flashing work actually costs in Southeast Michigan in 2026:
Flashing Repair (Isolated Problem)
Chimney flashing replacement: $800–$1,500 depending on chimney size and whether a cricket is needed
Valley flashing repair: $400–$800 per valley, depending on length and accessibility
Wall intersection flashing: $600–$1,200 depending on length and whether siding needs to be removed
Kickout flashing installation: $150–$300 per location
These are repair costs for situations where the roof is otherwise in good condition and only the flashing needs attention. If the roof decking is rotted or the shingles around the flashing are damaged, costs go up.
When Repair Makes Sense
Flashing repair is the right call when:
Your roof is less than 10 years old and the shingles are in good condition
The leak is isolated to one area (one chimney, one valley)
The roof decking is solid with no rot
You're planning to sell in the next few years and just need to stop an active leak
When Full Replacement Makes More Sense
If your roof is 15+ years old, has multiple flashing problems, or shows signs of widespread deterioration, replacing the whole roof is usually smarter than piecemeal repairs. Here's why:
You're paying for mobilization, setup, and cleanup whether we're fixing one valley or replacing the whole roof
Old shingles are brittle and often break when we remove flashing, requiring additional repairs
If one area is failing, others are likely close behind
A full roof replacement in Metro Detroit comes with a warranty on materials and labor; patchwork repairs don't
A full roof replacement on an average 2,000-square-foot home in Southeast Michigan runs $8,000–$15,000 depending on shingle quality, roof complexity, and how much decking needs replacement. That includes all new flashing installed correctly.
Insurance Coverage
Homeowners insurance typically covers flashing damage if it's caused by a covered peril — wind, hail, falling tree, etc. It usually doesn't cover deterioration from age or poor installation.
If you've had storm damage, we can work with your insurance adjuster to document the damage and make sure the claim includes all necessary flashing work. We've worked with every major insurance company in Michigan and know what they require for documentation.
A note on "insurance specialists" who knock on your door after a storm: Be cautious. Some of these contractors inflate estimates, push unnecessary work, or do substandard repairs that fail within a few years. We don't chase storms or knock on doors. We're a local company that's been here since 1988, and we'll be here when your roof needs work in 20 years. That's the difference.
Ready to Get Started?
NEXT Exteriors has been protecting Michigan homes since 1988. Whether you need flashing repair, a full roof replacement, or just an honest assessment of what's going on, we'll give you straight answers and fair pricing. No pressure, no gimmicks — just old-school contractor values.
Or call us: (844) 770-6398
Other Services from NEXT Exteriors
While we're known for our roofing expertise, NEXT Exteriors offers a complete range of exterior services in Detroit and throughout Southeast Michigan. If your home needs seamless gutters in Detroit, MI to properly channel water away from your foundation, we install 5-inch and 6-inch K-style gutters with hidden hangers for maximum durability. We're also Detroit window experts specializing in energy-efficient replacement windows that reduce drafts and lower heating bills — critical in Michigan winters. And because a well-insulated home prevents the attic heat loss that causes ice dams and flashing failures, our top-rated insulation contractor services in Detroit include attic insulation, spray foam, and air sealing that work hand-in-hand with proper roofing.
Frequently Asked Questions About Roof Flashing Failures
Can flashing be repaired or does it need replacement?
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It depends on the extent of the damage. Minor issues like loose counter flashing or deteriorated sealant can often be repaired. But if the flashing is rusted through, improperly installed, or causing rot in the roof decking, replacement is the only reliable fix. We don't patch problems that will fail again in a year — we fix them right the first time.
How long does roof flashing last in Michigan?
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Properly installed aluminum or galvanized steel flashing lasts 20–30 years in Michigan's climate. Copper flashing can last 50+ years. But those lifespans assume correct installation. Poorly installed flashing can fail in 5–10 years, especially around chimneys and valleys where water flow is concentrated. The quality of installation matters more than the material.
Will homeowners insurance cover flashing repairs?
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Insurance typically covers flashing damage caused by storms, wind, hail, or falling debris. It usually doesn't cover deterioration from age or poor installation. If you've had recent storm damage, document it with photos and contact your insurance company before making repairs. We can work with your adjuster to make sure the claim includes all necessary flashing work.
Can I see flashing problems from the ground?
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Sometimes. Use binoculars to inspect visible flashing around chimneys and in valleys. Look for rust, lifted edges, gaps between metal and brick, or missing sealant. But many flashing problems aren't visible from the ground — they're hidden under shingles or behind siding. If you see interior water stains or suspect a problem, get a professional inspection. We offer free assessments.
What's the difference between step flashing and continuous flashing?
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Step flashing consists of individual L-shaped pieces installed between shingle courses, creating a stair-step pattern up a wall or chimney. Each piece overlaps the one below it. Continuous flashing is a single long piece bent at 90 degrees. Step flashing is the correct method for roof-to-wall intersections because it allows for expansion and contraction without buckling. Continuous flashing is faster to install but fails over time.
Do all chimneys need a cricket?
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Michigan building code requires a cricket (also called a saddle) on the uphill side of any chimney wider than 30 inches. The cricket diverts water around the chimney instead of letting it pool behind it. Even on smaller chimneys, a cricket is good practice in Michigan because of our heavy snow loads and ice dam risk. Many older homes don't have crickets, which is why chimney leaks are so common.
How do I know if my roofer installed flashing correctly?
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Ask to see photos of the flashing installation before the shingles go on. Proper flashing should be layered, with each piece overlapping the one below. There should be ice-and-water barrier under all flashing in valleys and around chimneys. Step flashing should be woven between shingle courses, not nailed on top. And there should be kickout flashing at the bottom of every roof-to-wall intersection. If your roofer can't explain how they're flashing these areas, find someone else.