Question 1

What is the Interlock® Slate & Cedar Shingle roofing system, and what is it made of?

Accepted Answer

It is a four-way interlocking aluminum shingle system: each panel is roll-formed from .019"-gauge aluminum and finished with the proprietary Alunar® Coating System for a low-gloss, fade-resistant designer finish. Because all four edges of every shingle lock into the adjacent panels, the field behaves as a continuous, wind-locked assembly rather than individual loose shingles. A full range of color-matched aluminum trims — ridge, valley, sidewall/endwall, and chimney backpan and collar — completes the system for a weather-tight envelope.

Question 2

How does a metal roof that looks like slate compare to genuine slate or asphalt shingles?

Accepted Answer

It reproduces the dimensional look of natural slate at a fraction of the weight and risk. Real slate and concrete tile are heavy and brittle, while asphalt shingles typically last only 15–25 years and are prone to cracking, curling and granule loss. Interlock's aluminum shingles won't rot, crack, curl or rust, are engineered as a lifetime system, and carry a one-time-transferable lifetime limited material warranty — slate aesthetics without the structural load or the recurring tear-off cost.

Question 3

How much does Interlock Slate weigh, and does the roof structure need reinforcement?

Accepted Answer

The system weighs less than 7% of a typical concrete-tile roof and under 30% of standard asphalt shingles — on the order of 40–50 lbs per 100 sq ft (one square) versus 700–900+ lbs for tile. That low dead load generally allows installation without engineered structural reinforcement and, on a sound deck, often directly over the existing roof. Final confirmation should always be made against the project's structural documents, but most residential retrofits require no framing upgrade.

Question 4

What roof slope (pitch) is required, and what are the underlayment rules?

Accepted Answer

Minimum slope is 3:12 when a self-adhered Ice & Water shield membrane is applied across the deck, or 5:12 minimum with standard synthetic underlayment. The entire roof area must be covered with synthetic roofing underlayment before shingle installation, over minimum ½" exterior-grade sheathing or closely fitted boards. These thresholds, together with the matched flashing details (valley trim, chimney backpan and collar, sidewall/endwall trims), are specified in the installation manual to maintain the weather-tight rating.

Question 5

Is Interlock Slate a "cool roof," and can it lower energy costs?

Accepted Answer

Yes — Interlock roofs are Cool Roof rated, with solar-reflectance and thermal-emittance performance verified under the Cool Roof Rating Council (CRRC) program and Oak Ridge National Laboratory (ORNL) testing. Reflective finishes reduce attic heat gain, which can lower cooling demand in warm climates and may contribute to ENERGY STAR or Title 24-type energy compliance depending on the color selected. Specific solar-reflectance and emittance values by color are published in the Interlock Energy Star & Solar Reflectance data sheet.

Question 6

Is the aluminum recyclable, and how sustainable is the system?

Accepted Answer

The shingles use an aluminum base that is sustainable and fully recyclable at end of life — aluminum is among the most recycled building materials in the world. Because the roof is engineered to last a lifetime rather than be replaced every 15–20 years, it avoids the repeated asphalt tear-offs that send roofing waste to landfills over the life of a building. Combined with its cool-roof reflectivity, it supports green-building objectives and can contribute to LEED-type material and energy credits.

Question 7

What warranty covers Interlock Slate & Cedar Shingle, and is it transferable?

Accepted Answer

The system is backed by the Guardian lifetime limited material warranty, which is one-time transferable to a subsequent homeowner — a meaningful resale advantage over the prorated warranties typical of asphalt shingles. Coverage applies to the material and the Alunar® finish under normal residential use, with 50-year coverage extended to the next homeowner on transfer. Full terms and conditions are detailed in the Guardian Warranty document, and registration should be completed and retained to preserve transfer rights.

Question 8

Is Interlock Slate code-compliant and third-party tested?

Accepted Answer

Yes — Interlock aluminum roofing carries independent code and performance validation. It holds an ICC-ES Evaluation Report (ESR-1790) for building-code compliance, Florida Building Code Product Approval (FL7263-R7) for high-wind and high-velocity-hurricane-zone use, and UL 2218 Class 4 impact (hail) certification, the highest impact rating issued. These reports give architects, builders and code officials the documentation needed for permitting and specification, and each is available as a separate download in this library.

Question 9

How does the roof perform in snow, wind, hail and freeze-thaw climates?

Accepted Answer

The four-way interlock mechanically ties every shingle to its neighbors, producing a wind-resistant, near-monolithic field that resists uplift and sheds snow rather than trapping it. The UL 2218 Class 4 rating means the panels withstand the impact of a 2-inch steel ball without cracking — the top hail rating, which can qualify homeowners for insurance premium discounts in hail-prone regions. The non-porous aluminum and interlocking design also resist the freeze-thaw cycling and ice-damming damage that degrade slate, tile and asphalt over time.

Question 10

Can Interlock Slate be installed over an existing roof, and what does that save?

Accepted Answer

In most cases yes — its very low weight allows installation over a structurally sound existing roof deck without a full tear-off, reducing labor, disposal fees and project disruption. Eliminating tear-off also keeps the home weather-protected throughout installation and avoids landfill tipping costs. The manual specifies deck condition, underlayment and fastening requirements; where the existing surface is uneven or deteriorated, removal and re-decking is recommended.

Interlock® Slate & Cedar Shingle Metal Roofing — Specification & Installation Manual

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