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Solid Copper Slate Roofing | 99.9% Pure Architectural Copper | Interlock®

Metal Roofing Products

Interlock® Solid Copper Slate Roofing

The appearance of quarried natural slate in 99.9% pure architectural copper — engineered for heritage homes, civic landmarks, and generational residential architecture. Backed by the Interlock® Lifetime Transferable Warranty.

Interlock® Solid Copper Slate Roofing reproduces the silhouette of quarried natural slate in a material whose verifiable service life is measured in centuries — solid Copper Alloy C11000 conforming to ASTM B370, finished by atmospheric chemistry rather than applied coating.

Overview

What Is Interlock® Solid Copper Slate Roofing?

Interlock® Solid Copper Slate Roofing is the appearance of quarried natural slate executed in 99.9% pure electrolytic tough-pitch copper (Copper Alloy C11000) conforming to ASTM B370 — the recognized North American standard for cold-rolled architectural copper sheet. The profile matches Interlock's aluminum Metal Slate panel geometry (17⅝" × 9" face) for visual continuity with the heritage residential aesthetic; the substrate is solid copper rather than coated aluminum.

Color is intrinsic to the metal — no PVDF coating, granule layer, or applied finish to fail. Newly installed Copper Slate panels arrive bright salmon-pink and progress through a documented oxidation sequence: russet bronze within weeks (cuprite, Cu₂O), matte chocolate brown across one to three years (tenorite, CuO), and ultimately the iconic verdigris green-blue patina — a stable copper-sulfate/hydroxysulfate stratum of brochantite, antlerite, and posnjakite that becomes the roof's own self-renewing protective mineral barrier. The same metallurgical process has preserved the cladding of the Statue of Liberty (installed 1886), the U.S. Capitol Dome (1863), Christ Church Philadelphia (1727), and copper-roofed cathedrals across Europe in continuous service for more than eight hundred years.

At approximately 100–125 lbs per square (16 oz or 20 oz architectural copper sheet), structural assessment is recommended for retrofit applications. Solid copper carries an inherent Class A fire rating (copper melts at 1,984°F — well above sustained Class A test temperatures), UL 2218 Class 4 impact resistance, and wind-uplift performance evaluated to ASTM E1592 — specified under CSI MasterFormat 07 41 13 (Metal Roof Panels) and conforming to IBC §1507.4 and IRC §R905.10. Solar-array compatible, 100% recyclable at end of service, free of fluoropolymers and plasticizers, and backed by the Interlock® Lifetime Transferable Warranty applied to a material whose service life is documented in centuries.

Who It's For

Interlock® Solid Copper Slate for Heritage, Architects, and Specifiers

You're investing in a roof that becomes part of the architecture rather than a periodic replacement expense. Interlock® Solid Copper Slate gives you the look of quarried slate — the most prestigious traditional residential roofing material — in a substrate that develops a living finish rather than degrading toward replacement. The patina is the material's protective system; you will not paint, re-coat, or re-shingle this roof in your lifetime, your children's lifetime, or likely your grandchildren's lifetime. Backed by the Interlock® Lifetime Transferable Warranty applied to a material whose documented service life is multi-century.

Interlock® Solid Copper Slate is specified under CSI MasterFormat 07 41 13 (Metal Roof Panels). The substrate is Copper Alloy C11000 cold-rolled to architectural sheet per ASTM B370, supplied in 16 oz (~0.0216") or 20 oz (~0.027") nominal weight. Panel geometry matches Interlock Metal Slate: 17⅝" × 9" face exposure on the four-way interlocking concealed-fastener system, with stainless steel fasteners specified throughout to prevent galvanic corrosion. Performance: UL 790 Class A fire (inherent / non-combustible per ASTM E136), UL 2218 Class 4 impact, ASTM E1592 wind-uplift, IBC §1507.4 / IRC §R905.10 conformance. Sustainability: 100% recyclable, no fluoropolymers, contributes to LEED Materials & Resources credits and applicable Environmental Product Declarations. Full panel profile drawings, fastener schedules, and CSI-formatted submittal language available on request.

Interlock® Solid Copper Slate installs using the four-way interlocking concealed-fastener system common to the Interlock® aluminum and copper lines, with stainless steel fasteners specified throughout to prevent galvanic corrosion. Copper requires careful detailing for runoff management (copper-laden water will stain unsealed masonry, concrete, and limestone if drainage is unmanaged) and incompatible-metal contact must be avoided. Certified Interlock installers receive copper-specific training and technical support, and patina-accelerant solutions are available for projects requiring a fully weathered appearance at completion. Contact your regional Interlock representative to discuss copper dealer opportunities.

KEY ADVANTAGES

The Interlock® Solid Copper Slate Advantage

Multi-Century Service Life

Copper roofing carries the only roofing service record measured in centuries rather than decades. The Statue of Liberty’s copper cladding (installed 1886), the U.S. Capitol Dome (1863), and copper-roofed cathedrals across Europe documented in continuous service for more than eight hundred years demonstrate the same metallurgical performance you specify for your home.

Class A Inherent Fire Resistance

Copper is inherently non-combustible — melting point 1,984°F, well above sustained Class A test temperatures, and certified non-combustible per ASTM E136. The fire classification is achieved by the material itself, not by an underlayment-dependent assembly. The strongest residential fire performance specification available.

Naturally Evolving Patina Finish

Color is intrinsic to copper — no paint film, PVDF coating, stone granule, or organic binder to chalk, fade, peel, or delaminate. The roof’s appearance evolves through documented chemistry: salmon-pink at installation, russet bronze within weeks, chocolate-brown CuO across one to three years, ultimately the iconic verdigris green-blue patina. This is not deterioration — it is the engineered service life of the material expressing itself.

UL 2218 Class 4 Impact / 120 mph Wind

Solid Copper Slate carries the highest UL 2218 hail-impact classification (Class 4) and is warranted to 120 mph wind resistance — backed by both the inherent strength of solid copper sheet and Interlock’s four-way interlocking concealed-fastener installation system, with wind-uplift evaluated to ASTM E1592.

100% Recyclable Architectural Material

Architectural copper is among the most circular materials in the built environment — 100% recyclable at end of service without performance loss, routinely fabricated with substantial recycled content per Copper Development Association data, and qualifying for LEED Materials & Resources credits and applicable Environmental Product Declarations.

Lifetime Transferable Warranty

Backed by the Interlock® Lifetime Transferable Warranty — applied to a material whose verifiable service life, documented across centuries of monumental, ecclesiastical, and heritage residential applications, makes solid copper the most defensible long-term roofing investment in the residential category.

Technical Data

Product Specifications

Base Material & Alloy Specification	Copper Alloy C11000 (electrolytic tough-pitch copper, 99.9% pure) cold-rolled to architectural sheet per ASTM B370
Panel Gauge & Nominal Weight	16 oz/ft² (~0.0216" / 0.549 mm) or 20 oz/ft² (~0.027" / 0.686 mm) — expressed by weight designation per industry standard
Installed Weight Per Square	~100 lbs per 100 sq ft (16 oz copper) or ~125 lbs per 100 sq ft (20 oz copper) — structural assessment recommended for retrofit applications
Hail Impact Resistance Rating	Class 4 — UL 2218 (highest classification issued)
Fire Resistance Rating	Class A (inherent / non-combustible per ASTM E136; copper melting point 1,984°F)
Wind Speed Resistance — Manufacturer Warranted	120 mph (193 kph) warranted; wind-uplift evaluated to ASTM E1592
Surface Finish System	None applied. Copper develops a natural multi-stage atmospheric patina (cuprite Cu₂O → tenorite CuO → verdigris [brochantite, antlerite, posnjakite]) — the material's self-passivating protective system
Panel Size, Weather Exposure & Coverage Geometry	17⅝" × 9" face exposure (matches Interlock® Metal Slate panel geometry for design continuity with the aluminum line)
Material Warranty Program Name	Interlock Lifetime Transferable Warranty (Guardian Lifetime Limited Non-Prorated Material Warranty)
Warranty Duration, Ownership Terms & Transferability	Lifetime for original registered owner; transferable (one-time) — applied to a material with documented multi-century service life
Recycled Content & End-of-Life Recyclability	100% recyclable at end of service. Architectural copper is routinely fabricated with substantial recycled content per Copper Development Association data
Building Code Conformance & Sustainability Credits	Conforms to IBC §1507.4 and IRC §R905.10 (metal roof panels). Contributes to LEED Materials & Resources credits; Environmental Product Declarations available
CSI MasterFormat Division & Section Reference	07 41 13 — Metal Roof Panels

Available Colors

Patina Evolution — The Living Finish

Interlock® Solid Copper Slate is offered as a single architectural specification rather than a color palette — because copper is not a finish applied to a substrate; it *is* the substrate. Every panel is roll-formed from 99.9% pure electrolytic tough-pitch copper (Copper Alloy C11000, ASTM B370). Color is intrinsic to the metal: there is no paint film, PVDF resin, stone granule, or organic binder to chalk, fade, peel, delaminate, or fail by UV exposure. What replaces a fixed color is a documented oxidation sequence — the same self-passivating chemistry that has preserved the cladding of the Statue of Liberty (1886), the U.S. Capitol Dome (1863), Christ Church Philadelphia (1727), and copper-roofed cathedrals across Europe in continuous service for more than eight hundred years. New Interlock® Solid Copper Slate arrives bright salmon-pink and progresses through measurable stages: russet bronze within weeks as cuprite (Cu₂O) forms; matte chocolate-brown tenorite (CuO) across one to three years; and ultimately the iconic verdigris green-blue — a stable copper-sulfate/hydroxysulfate stratum of brochantite (Cu₄SO₄(OH)₆), antlerite (Cu₃SO₄(OH)₄), and posnjakite (Cu₄SO₄(OH)₆·H₂O) that becomes the roof’s own mineral protective barrier. Patina is not deterioration — it is the engineered service life of the material expressing itself. Because copper is a single specification, not a palette, Interlock provides physical material samples rather than printed swatch cards. Contact your local Interlock dealer to request a solid-copper sample and full architectural specification sheet, including current gauge availability, panel profile drawings, fastener schedules, and CSI 07 41 13 specification language for project submittals.

Material Comparison

Solid Copper Slate vs. Natural Quarried Slate vs. Asphalt Shingles

How does Interlock® Solid Copper Slate compare to natural quarried slate and the alternatives a homeowner typically considers for heritage residential roofing? The numbers tell a clear story about service life, weight, fragility, and lifetime financial logic.

	Interlock® Solid Copper Slate	Natural Quarried Slate	Asphalt Shingles
Lifespan	100-200+ years (documented)	75-200 years (prone to breakage)	15-25 years
Weight	~100-125 lbs/square (16 oz / 20 oz)	800-1,500 lbs/square (requires structural reinforcement)	250-350 lbs/square
Fire Rating	Class A (inherent / non-combustible)	Class A (non-combustible)	Class A (with mat)
Warranty	Lifetime Transferable	Limited / quarry-specific	20-30 year limited
Maintenance	Essentially maintenance-free (patina self-passivates)	Regular inspection, individual tile replacement	Periodic inspection, re-nailing

Environmental Performance

Sustainability & Energy Efficiency

Interlock Copper Roofing is the most sustainable premium roofing material available — a 100% natural, 100% recyclable solid copper product with no synthetic coatings, no chemical treatments, and no landfill contribution at end of life. Copper’s multi-century service life produces the lowest embodied carbon per year of use of any roofing material on the market. Interlock Copper is certified as a Green Roofing Product, requires zero maintenance throughout its lifespan, and retains full material recovery value when eventually recycled. For architects, developers, and homeowners committed to genuine long-term environmental performance, Interlock Copper Roofing is the definitive sustainable roofing specification.

Interlock Copper may contribute to LEED v4 credits under Materials & Resources (MR) — Recycled Content, and Energy & Atmosphere — Enhanced Energy Performance. Contact your Interlock dealer for LEED documentation support.

Verified Customer Reviews

What Homeowners Say About Interlock Metal Roofing

This is the 3rd roof I have had put on by Interlock Roofing. I put one on my original house, my cottage, and now my new house. They have always done an excellent job, and the aluminum shingles are a great product — light, sturdy, and good-looking, even years down the road.

Bruce M.Wakefield, MA

We had our roof replaced in 2017 with an aluminum roof by Interlock Metal Roofing. We live on the lake, and prior to the replacement, we were spending thousands of dollars every year as the shingles used to fly away in the wind. We have never had any problems in the last 9 years. We had a great experience with Interlock Metal Roofing. They were very professional and did a beautiful job, although it was difficult as our roof is quite high. Our roof is still beautiful, and we have never had a worry about it.

Beena M.Sudbury, ON

I LOVE MY INTERLOCK ROOF! No more climbing up there to clean it off, no more gritty stuff falling into my garden after a few years. It looks fabulous and does what it's supposed to! And then there are the installers: knowledgeable, attentive to detail, and personable. Ivan is a gem! He attended to the addition of a small bit of flashing efficiently and cleaned the whole roof with a blower in short order. After almost ten years, it's STILL the only roof I would choose!

Sue Lyn T.Corvallis, OR

FAQ

Frequently Asked Questions About Solid Copper Slate Roofing

What is Interlock® Solid Copper Slate Roofing?

Interlock® Solid Copper Slate Roofing is the appearance of quarried natural slate executed in 99.9% pure electrolytic tough-pitch copper (Copper Alloy C11000) conforming to ASTM B370. Panel geometry matches the aluminum Metal Slate profile at 17⅝” × 9″ face exposure on the four-way interlocking concealed-fastener system. The substrate is solid copper — not coated aluminum, not copper-plated steel, not copper foil. Service life is measured in centuries rather than decades, and every panel is backed by the Interlock® Lifetime Transferable Warranty.

How long does a copper slate roof last compared to natural quarried slate?

Both are multi-century materials, but with different failure modes. Natural quarried slate is documented at 75–200+ years when installed perfectly, but is prone to fracture under hail impact and ice loading — individual tile replacement becomes ongoing maintenance. Solid copper is documented at 200+ years (Christ Church Philadelphia, 1727; European cathedrals in continuous service for more than eight centuries) without the fracture liability — copper deforms slightly under exceptional impact but does not crack or shatter, and the patina layer actively protects against further oxidation.

Is copper slate roofing too heavy for my home's existing roof framing?

No — and this is one of solid copper slate’s defining specification advantages. At approximately 100–125 lbs per square (16 oz / 20 oz architectural copper sheet), Interlock® Solid Copper Slate is roughly one-tenth the installed weight of natural quarried slate (800–1,500 lbs/sq). Structural assessment is recommended for retrofit, but the vast majority of residential roof framing carries it without reinforcement. Natural slate, by contrast, frequently requires structural upgrades for retrofit installation.

Does the copper patina happen evenly, or will my roof look patchy?

Patina development is determined by atmospheric exposure — sun, rain, prevailing wind, and proximity to industrial or marine air. Sheltered areas under eaves, dormers, or tree canopy patina more slowly than fully exposed planes, so during the bronze-to-verdigris transition (years 5–25 in most climates) a roof can show measurable color variation. This is considered architecturally desirable in heritage applications — landmark copper roofs deliberately preserve this character. For projects requiring uniform appearance at completion, Interlock dealers can apply professional patina-accelerant solutions during installation.

How does the cost of copper slate compare to natural quarried slate?

Upfront, the two materials are comparable — both are premium architectural specifications priced well above asphalt or aluminum. Over a 100-year ownership window, copper slate is typically the lower-cost option once you factor in natural slate’s recurring individual-tile replacement labor, the structural reinforcement frequently required at installation for the 800–1,500 lbs/sq dead load, and the substantial commodity salvage value copper retains at end of service. Contact your local Interlock dealer for project-specific pricing.

Can the verdigris patina be accelerated for project completion?

Yes. Interlock-certified copper installers can apply professional patina-accelerant solutions during installation that produce a fully weathered bronze or verdigris appearance at project completion, rather than waiting decades for natural atmospheric development. This is common practice on heritage restoration projects where new copper needs to visually match adjacent aged copper, and on civic projects with completion-day aesthetic requirements. Accelerant-treated copper continues to develop and stabilize naturally over time.

Will copper runoff stain my masonry, stone, or limestone exterior?

It can — and this is the single most important detailing consideration with any copper roof. Copper-laden water carries dissolved copper salts that will stain unsealed masonry, concrete, limestone, and some stucco compositions if drainage is unmanaged. Interlock installations are specified with proper gutters, downspouts, drip-edge management, and stainless steel hardware throughout to direct runoff away from staining-vulnerable surfaces. Certified Interlock installers are trained on copper-specific detailing — this is one of the reasons solid copper is installed via the dealer network rather than as a DIY product.

Is copper slate worth the investment on a heritage home retrofit?

For homes where architectural authenticity, multi-generational service life, and resale-value preservation are project priorities, solid copper slate is among the most defensible roofing specifications available. Documented installations from the 1700s remain in continuous service today. The Lifetime Transferable Warranty adds documentable resale value, and copper’s status as a permanent architectural material is recognized by heritage preservation authorities and historic-district review boards across North America.

Can copper slate be installed in coastal salt-air environments?

Yes — copper performs exceptionally well in coastal environments and is in many cases the preferred material specification. Unlike galvanized or Galvalume steel (which can fail at cut edges and fastener penetrations in salt-air exposure) and aluminum (which performs well but can develop oxide bloom in chloride-rich environments), copper develops a chloride-stabilized patina compound system that is fully compatible with marine atmospheres. Copper roofing on coastal civic and ecclesiastical buildings is documented in continuous service for centuries.

What insurance discount can copper slate roofing qualify for?

Solid Copper Slate carries the highest UL 2218 hail-impact classification (Class 4) and the strongest fire performance specification available (Class A inherent / non-combustible per ASTM E136). Insurers in hail-prone states (Texas, Oklahoma, Kansas, Colorado, the Carolinas) offer Class 4 premium discounts ranging from 5% to 35%, and wildfire-zone Class A discounts in California, Arizona, and Colorado. Contact your insurance provider with the Interlock® specifications and the Guardian Lifetime Warranty documentation to confirm applicable credits.