Interlock Shake: Aluminum Shake Roofing Specs & Benefits
Quick answer
Interlock Shake is an aluminum, shake-look roofing system finished with the Alunar coating. Each panel is 0.028-inch aluminum, 47 inches long with a 12.5-inch weather exposure and a 3-panel overlap, weighs a fraction of wood or asphalt, and carries Interlock's non-prorated, one-time-transferable lifetime warranty.
What is Interlock Shake?
Interlock Shake is an interlocking aluminum panel embossed with the deep grain of hand-split cedar shake and finished in the Alunar coating with color-matching trims. Unlike real cedar, it will not rot, split, curl, absorb water, or feed a fire, and unlike asphalt it will not granule-shed or blow off in high wind. The panels lock together and include an anti-capillary detail that stops wind-driven water from tracking back under the course above.
Specifications at a glance
Each Shake panel is 0.028-inch aluminum, 47 inches long with a 12.5-inch course-to-weather exposure and a 3-panel overlap on the side lap. It installs over a minimum 1/2-inch solid sheathing covered with synthetic underlayment, at a minimum roof slope of 3:12 with an ice-and-water underlayment or 4:12 with a standard underlayment. The finished roof weighs less than 7% of a concrete tile roof and less than 30% of asphalt, so no special structural preparation is required.
Why homeowners choose it
It delivers the warmth of a cedar-shake roof with none of cedar's upkeep or fire and rot risk. Aluminum cannot rust; the interlocking panels stand up to severe weather and wind; and the Cool Roof-rated finish helps keep the home cooler and cut summer energy costs. It is low-maintenance, recyclable, light enough to install over an existing roof, and backed by a non-prorated, one-time-transferable lifetime warranty — meaning coverage is not reduced or depreciated over time.
What to expect with installation
Authorized installers lay the panels over solid sheathing and full synthetic underlayment, starting at the eave and hooking each course into the one below. Panels overlap on the side and fasten to the deck with concealed clips and fasteners, so no fasteners are exposed to the weather. Following the minimum slope, underlayment, and fastening requirements keeps the warranty valid.
Frequently Asked Questions
Is a metal shake roof better than real cedar?
For longevity and upkeep, most homeowners think so. Interlock Shake captures the cedar look but will not rot, split, curl, or burn, needs virtually no maintenance, and is backed by a lifetime warranty — where real cedar requires ongoing treatment and has a limited service life.
Is Interlock Shake fire safe?
Aluminum is non-combustible, and Class A or Class B roof assemblies are available under ICC-ES ESR-1790 when the specified underlayment is used. That is a meaningful advantage over combustible wood shake, especially in wildfire-prone areas.
Can it be installed over my existing roof?
Typically yes — at under 30% the weight of asphalt, Interlock Shake installs over solid sheathing without special framing. Your installer verifies the deck, slope, and local code.
What slope does Interlock Shake require?
A minimum of 3:12 with an ice-and-water underlayment, or 4:12 with a standard underlayment.
Sources
- Interlock Shake Specification Manual — Product specifications
- ICC-ES ESR-1790 — Shake panels — Fire & wind classification
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Last reviewed 2026-07-11 · Reviewed by Scott Plumptree, Director of Marketing