Why Northbrook Homeowners Are Choosing Copper Flashing Over Aluminum: Lifespan, Patina, Cost and What It Looks Like on a Mature North Shore Home
Why Northbrook homeowners are specifying soldered copper flashing over aluminum on cedar, slate, and architectural shingle re-roofs.
What changed in the last decade
Ten years ago, aluminum flashing was the standard specification on the majority of Northbrook re-roofs — including on cedar shake and architectural shingle homes in the Mission Hills, Royal Ridge, and Sunset Ridge neighborhoods. Aluminum was cheaper, lighter, easier to work, and acceptable to most homeowners for the flashing scope. Today, we're specifying soldered copper flashing on roughly 60% of estate-tier Northbrook re-roofs and the percentage is climbing year over year. The change isn't driven by us pushing copper — it's driven by Northbrook homeowners who've seen what aluminum looks like at year 12-15 and what copper looks like at year 30, 50, 80 on neighbor properties.
Lifespan: the math homeowners are running
Aluminum flashing on a Northbrook home typically delivers 20-25 years of service life before pinhole corrosion, edge oxidation, or sealant failure start producing leaks. The flashing then has to be addressed as a repair scope independent of the rest of the roof — which often means tear-back of shingles or shake courses to access the failed flashing. Copper flashing, installed correctly and soldered (not just lap-sealed), routinely delivers 80-100 year service life. On Northbrook estate homes, copper flashing has outlived the original cedar shake roof, the replacement cedar shake roof, and is still in serviceable condition for the third roof going on above it. Homeowners doing the lifecycle math — especially homeowners who intend to be in the home for 20+ years — are concluding that copper at 2-3x the upfront cost is actually cheaper across two roof replacements.
Where copper specifically goes on a Northbrook re-roof
Step flashing at every dormer and wall intersection — the most common leak point on a complex Northbrook roofline. Counter-flashing where the roof meets a chimney or wall — soldered into the masonry rather than caulk-sealed. Apron flashing along chimney fronts. Valleys (open copper valleys are a high-end specification that some Northbrook homeowners want for character; closed valleys with copper underlayment are more common). Drip edge at eaves and rakes. Pipe boots and stack flashings where soldered copper collars dramatically outperform rubber-and-aluminum stack flashings. Bay window and dormer roof systems. On a typical Northbrook estate-home re-roof, the copper scope adds $8,000-$25,000 to the project depending on architectural complexity — within a $60K-$150K total project, that's a 10-15% premium for the flashing that historically drives 60%+ of long-run leak repairs.
The patina question
Copper installs bright and gradually transitions through a series of color states — first to a darker bronze (12-24 months), then through a brown phase (3-7 years), and eventually to the classic verdigris green (15-25 years depending on exposure and air chemistry). On Northbrook homes where the architectural intent is a traditional aesthetic, the patina is part of the appeal — the roof improves visually as it ages, which is the opposite of every other material we install. Some homeowners want to preserve the bright copper look longer and will specify a clear protective coating on install, which delays patina by 5-10 years. The majority specify untreated copper and let it weather. Either is acceptable; there's no functional performance difference.
Aluminum still has its place
We're not anti-aluminum. On Northbrook homes where the homeowner doesn't intend to stay 15+ years, on rental properties, on properties where the budget genuinely constrains the project, aluminum flashing is acceptable and we install it routinely. The decision matters most on estate-tier homes where the homeowner is making a once-in-30-years specification call. If the home is going to be in the family for two generations, copper is almost always the right call. If the home is going to sell within 5-7 years, aluminum's lower upfront cost rarely pays back in the form of a higher sale price — most buyers don't see the flashing. Run the math against your actual ownership timeline, not the showroom appeal of premium materials.
What we specify on Northbrook re-roofs
Our default specification on Northbrook estate-tier projects is soldered copper at all chimney flashing, step flashing on dormers and wall intersections, pipe stack collars, and drip edges. We use aluminum on open-field flashings (where applicable) only by exception. On cedar shake reroofs in particular, copper is the only flashing that comes close to matching the cedar's expected lifespan — putting 25-year aluminum flashing on a 30-year cedar roof creates a built-in midlife failure that we'd rather avoid. Copper flashing and sheet metal flashing are both core services we provide across the North Shore.
Get a copper-vs-aluminum scope on your Northbrook re-roof
We give every Northbrook estate-home customer a side-by-side scope showing copper and aluminum flashing as line items, with the cost delta clearly identified. You make the call based on your ownership timeline, aesthetic preference, and budget. There's no pressure to specify copper — but if you want the honest comparison from a 30-year Chicagoland roofer, that's what we'll give you. Call (708) 847-5418 or use our contact form to schedule a free assessment.