Most roof leaks in Chicagoland don't start in the middle of a shingle field. They start at the edges — at chimneys, walls, skylights, valleys, and penetrations where different roofing elements meet. That's where flashing lives, and when flashing fails, the water finds its way in. We install and repair all types of sheet metal and flashing for residential and commercial buildings across Cook, DuPage, and Lake Counties.
After 30 years of diagnosing leaks across Chicagoland, we can say with confidence: flashing is the most common culprit. Not shingles. Not membrane failures in the field. The transitions — chimney bases, step flashing at sidewalls, pipe boots, valley metal, drip edge — are where the vulnerabilities are, and they're where the water consistently enters when they're not done right or when they've deteriorated.
Illinois weather is particularly hard on flashing. The freeze-thaw cycle — which runs dozens of cycles per winter in this climate — puts continuous stress on caulked joints as metal expands and contracts with temperature. What was a sealed joint in October is a cracked joint by March. Understanding this dynamic is what separates flashing that lasts from flashing that fails in five years.
Every transition point on a roof has a flashing solution designed for it. We work with all of them, on new installations, re-roofing projects, and standalone repairs.
Individual L-shaped pieces that weave into shingle courses at sidewalls, dormers, and roof-to-wall intersections. Each piece laps the one below — it's a redundant system that sheds water progressively. The most common failure we see: step flashing that was caulked to the wall rather than counter-flashed, leading to inevitable joint failure as the structure moves.
The upper piece of the two-part chimney and masonry wall flashing system. Embedded in the mortar joint, it overlaps the step flashing below without rigidly connecting to it — allowing the chimney and roof to move independently. When the mortar joint deteriorates or counter flashing is never installed, water infiltration at chimneys follows reliably.
Metal valley lining protects the low point where two roof planes meet — the highest water-concentration point on any intersecting roof. We install open metal valleys on many applications, particularly where debris accumulation is a concern, and closed valleys where appearance dictates. Valley metal gauge and width matter in Illinois where ice and debris loads are significant.
Every plumbing vent, exhaust pipe, or mechanical penetration through a roof needs a properly sealed boot. Neoprene pipe boots on residential roofs typically last 15–20 years before the rubber deteriorates and cracks — a very common source of relatively small but persistent leaks. We replace pipe boots as a standalone repair and as part of every re-roofing project.
Drip edge runs along eaves and rakes to direct water off the roof edge and away from the fascia. It's required by most current building codes and by major shingle manufacturer warranties — yet it's still frequently omitted on older installations and sometimes on new work by less careful contractors. When drip edge is absent, fascia boards absorb water and rot, and soffit damage follows.
Skylights require a complete perimeter flashing system — usually a manufacturer-provided flashing kit for the specific skylight model installed with the specific shingle thickness. Improper skylight flashing is one of the most expensive-to-repair residential roof failures we see, because water infiltration at skylights can travel far before it's visible inside.
Hip caps and ridge flashing seal the highest points of a roof where wind-driven rain is most likely to find gaps. On metal roof systems, ridge caps are a critical component. On shingle roofs, proper hip and ridge cap installation — with appropriate exposure and nailing — affects both weather resistance and appearance.
On commercial flat-roof buildings with parapet walls, cap flashing covers the top of the parapet and is the first line of defense against water entering the wall assembly. Failed parapet caps are a consistent source of commercial building water infiltration and are frequently overlooked in routine maintenance. We fabricate and install custom-width parapet caps in galvanized steel or aluminum to match existing profiles.
Flat-roof commercial buildings use scuppers — wall openings that drain water off the roof — as an alternative or supplement to interior drains. Scupper boxes and the sheet metal transitions around them require careful fabrication and installation to prevent water intrusion at the wall penetration. Through-wall flashings at the base of parapet walls serve a similar purpose in waterproofing the roof-to-wall junction.
The most common flashing material on residential and commercial roofs across Chicagoland. Durable, relatively inexpensive, and readily available in standard profiles. Galvanized steel will rust eventually — typically at cut edges or in areas where the zinc coating has worn — but properly installed galvanized flashing should last 20 to 30 years. We use heavier-gauge galvanized where durability matters: valley metal, drip edge on wide overhangs, and commercial parapet caps.
Lighter than galvanized steel and won't rust. The trade-off is that aluminum is softer, more susceptible to physical damage, and is reactive with masonry and concrete — it requires separation from those materials to avoid galvanic corrosion. Aluminum is a good choice for step and counter flashing on standard residential applications where the lighter weight and rust resistance are advantages.
The premium choice for flashing on historic homes, estate properties, and high-end new construction. Copper is significantly more expensive than steel or aluminum, but it compensates with longevity — properly installed copper flashing with soldered or locked seams routinely lasts 50 years or more. It develops a characteristic green patina that many homeowners find attractive, particularly on older homes where it reads as historically appropriate. We do copper work on historic properties throughout the North Shore — Winnetka, Kenilworth, Lake Forest — where material authenticity matters as much as performance. Copper cannot be used in contact with pressure-treated lumber or aluminum without appropriate separation.
Lead flashing is still found on many older Chicagoland homes, particularly around chimneys and in valleys on houses built before the 1970s. It's extremely durable and malleable — it conforms well to irregular surfaces — but it's no longer used in new construction due to environmental concerns. Lead-coated copper is still available and is specified on some historic preservation projects where both durability and malleability are required. When we encounter lead flashing during re-roofing, we handle it in compliance with current regulations and replace it with an appropriate modern material.
The freeze-thaw cycle is the dominant factor. Northeastern Illinois experiences dozens of freeze-thaw cycles per year — temperatures swing above and below 32°F repeatedly from November through March, sometimes multiple times in a single week during the shoulder months. Every freeze-thaw event stresses the caulked joints at flashing laps and terminations. Metal expands in warmth and contracts in cold. Caulk, which is doing the work of bridging those gaps, fatigues with each cycle. A joint that's visually intact can be functionally failed — it looks okay from above but is no longer keeping water out.
Ice dams compound the problem. When a poorly ventilated roof allows snow melt to refreeze at the eaves, ice can work under step flashing and force water into wall cavities. Ice loads at valleys can displace valley metal. Any flashing that's relying on caulk alone — without the mechanical protection of properly lapped metal — is particularly vulnerable when ice is involved.
Old chimneys are the other chronic issue. Brick chimneys in Chicagoland, particularly those on homes built from the 1920s through the 1960s, often have deteriorated mortar beds at the flashing terminations. The counter flashing is no longer embedded in sound mortar — it's just sitting in crumbling joints. Water gets in behind the counter flashing, into the chimney assembly, and eventually into the attic or ceiling below. Fixing the flashing properly in this situation means tuck-pointing the mortar joints before re-flashing — something we coordinate with our chimney repair work.
Isolated failures are good repair candidates. A single cracked pipe boot, a section of step flashing that has lifted at one course, a counter flashing cap that's separated from its mortar joint in one location — all of these are addressable without replacing the entire flashing system. If the surrounding metal is sound, we repair the specific failure point. Repair costs for isolated flashing issues typically range from $500 to $1,500 depending on access and scope.
Chimney flashing repair — re-embedding counter flashing, replacing deteriorated step flashing on one side, resealing the base — falls in the $800 to $2,500 range depending on chimney size and the condition of the masonry.
When we see widespread caulk failure at a chimney that's been re-caulked multiple times, when step flashing has been improperly installed across a full wall run, or when the metal has corroded through in multiple locations — repair stops making financial sense. You're paying to fix individual failures on a system that's comprehensively done.
During any full roof replacement, we always replace all flashing. The cost differential is minimal when the labor to lift and relay shingles is already accounted for, and it prevents a scenario where new shingles outlive the old flashing. We consider this non-negotiable on re-roofing projects.
The location of water entry inside the house is the most useful clue. Leaks that appear at walls, chimneys, dormers, skylights, or near plumbing penetrations are almost always flashing failures — these are all transition points where two different roofing elements meet, and flashing is what waterproofs those transitions. A leak that appears in an open field of the roof, away from any penetration or wall, is more likely a shingle or membrane failure. If you can safely observe the roof from below after rain, look for water tracking along rafters or at wall plates — the water usually travels some distance from the entry point before it drips, so tracing it back to the source tells you where the flashing failure is.
It depends heavily on the material. Galvanized steel flashing — the most common type used on residential roofs — typically lasts 20 to 30 years, but the caulked joints often fail well before the metal itself corrodes. In Chicagoland's freeze-thaw climate, caulk at flashing joints cracks and separates within 5 to 10 years as the metal expands and contracts through hundreds of freeze-thaw cycles per year. Aluminum flashing has similar longevity to galvanized but is lighter and won't rust. Copper flashing, when properly installed with soldered or locked seams rather than caulked joints, can last 50 years or more — it's expensive up front but often outlasts the rest of the roof system on historic and high-end homes. Lead flashing, still found on some older Chicagoland homes, can also last many decades but is rarely used in new construction today.
Both are legitimate options depending on the extent of the problem. A single pipe boot that's cracked or a section of step flashing that's lifted can often be repaired directly — re-seating the flashing, replacing the boot, or applying compatible sealant at a failed joint. If the issue is isolated and the surrounding metal is in good condition, repair is the appropriate and cost-effective approach. The situation changes when we find widespread caulk failure at a chimney, when step flashing has been improperly installed across a full wall run, or when the metal itself has corroded through. At that point, repair compounds the problem — you're chasing individual failures on a system that's comprehensively failing. During a full re-roof, we always replace all flashing rather than try to preserve the old. The cost differential is minimal compared to the labor already involved, and it avoids a situation where the new shingles outlive the flashing.
Step flashing and counter flashing work together as a two-piece system at chimneys and walls. Step flashing is the lower piece — individual L-shaped metal pieces that weave into the shingle courses as they're installed, one piece per shingle course, running up the wall or chimney. Each piece laps the one below it so water sheds progressively downhill. Step flashing alone is sufficient at sidewalls and dormers. At chimneys and masonry walls, counter flashing is installed over the step flashing — it's embedded into the mortar joint of the masonry and overlaps the top of the step flashing, sealing the gap between the masonry and the step flashing beneath. The two pieces don't contact each other rigidly, which allows for independent movement as the chimney and roof structure expand and contract at different rates. This is an important detail: if a roofer caulks step flashing directly to the masonry without counter flashing, that caulk will fail in 5 to 10 years because there's nothing to accommodate the differential movement.
Yes. We install and repair copper flashing on historic and high-end residential properties across the North Shore and northwest suburbs. Copper requires specific skills — soldered or locked seams rather than relying on sealants, proper allowance for thermal expansion, and knowledge of which other metals copper can and can't be in contact with (it reacts galvanically with aluminum, for example). When copper flashings fail, it's usually because earlier repairs were done with incompatible materials or because the original soldered seams have opened. We can repair copper in place or replace sections using matching material. For full chimney or dormer flashings on older homes where the historic character matters, copper is often the appropriate choice — it develops a natural patina over time and, properly installed, will outlast virtually everything else on the roof.
We'll find the source of your leak and give you a clear diagnosis — whether it's a simple flashing repair or something more involved. Free estimates.