Metal Roofing in Chehalis, Washington — Lifetime Interlock® Aluminum Shingles Installed Locally

Yes—aluminum actually improves with freeze-thaw because it has no pores to trap water and crack. Chehalis averages about 45 freeze-thaw days per year with roughly 42 cm of snow, which is exactly the kind of climate where materials that absorb moisture fail fastest. Aluminum's oxide layer self-heals when scratched, so micro-damage from ice expansion doesn't propagate. The Alunar 70% PVDF fluorocarbon coating (warranted 30 years against fading) keeps the panel surface sealed. Compare that to asphalt, which becomes brittle in freeze cycles, or wood shakes, which split. You're looking at a roof that gets tougher as winters cycle through it.

The four-way interlocking panel design—each edge locks into the next—creates a continuous weather barrier that outperforms overlapped shingles. Chehalis receives about 1348 mm of rain annually, and with gusts routinely reaching 102 km/h, water gets driven sideways hard. Interlock's standing-seam and shingle profiles both shed water downslope before it can pool; the metal surface itself is non-porous, so water that reaches the underside has nowhere to soak in. Installed over a solid deck with underlayment, the system performs identically to asphalt in the rain—the metal is just the outer layer. Leaks come from installation gaps or flashing errors, not from the material itself.

Metal roofs shed snow faster than asphalt because the smooth, slippery surface doesn't grip it the way granules do, and the material expands and contracts with temperature swings—about 45 freeze-thaw days per year in Chehalis—creating tiny movements that loosen ice bonds. The four-way interlocking design distributes load evenly, and aluminum profiles (Slate, Cedar Shingle, Shake, Tile, Standing Seam) all have slopes engineered for drainage. If you want to keep snow for insulation or safety reasons, snow guards install on any profile. Aluminum is light enough—Shake installs at roughly 0.58 lb/sq ft—that even a heavy wet snow load stays well within structural limits without reinforcement.

Yes—that's one of aluminum's biggest practical advantages. Interlock's Tile profile (the heaviest option) weighs about 0.59 lb/sq ft, roughly 96% lighter than real slate or concrete tile. Your existing asphalt shingles are pulling roughly 2–3 lb/sq ft; the metal roof pulls less. This means no structural reinforcement, no engineer callout, and you avoid a costly tear-off and landfill haul. Most homes in Chehalis can accept a direct-over installation, which compresses the timeline and keeps labor costs down. The ICC-ES evaluation (ESR-1790, reissued 2025) confirms this method meets code for residential load paths.

Aluminum cannot rust because it contains no iron; instead, it forms a protective aluminum oxide layer that self-heals when scratched. This matters enormously in the Pacific Northwest's wet climate—1348 mm of rain per year and frequent gusts to 102 km/h mean moisture and salt spray constantly stress roofing materials. Steel metal roofs (used by competitors) require thick, expensive coatings because the base metal itself corrodes; once that coating chips, corrosion spreads underneath. Interlock uses roofing-grade 3105-H24 and 3003-H24 aluminum alloy (ASTM B209) with a Alunar 70% PVDF fluorocarbon finish on both sides—even if the topcoat fails, the underlying material is chemically immune to rust.

Chehalis experiences gusts around 102 km/h regularly, and Interlock's warranty covers wind speeds up to 120 mph (193 km/h) when installed to spec. The four-way interlocking design means each panel locks into its neighbors on all edges—top, bottom, left, right—so wind uplift has nowhere to find a weak seam. Contrast that with asphalt shingles, which nail down individually and rely on adhesive; once one shingle lifts, wind tears the rest. The aluminum profile doesn't degrade from UV or freeze-thaw the way that adhesive does. Proper installation by a trained crew (Interlock Metal Roofing PNW Inc. has served the region since 1997) is critical, but the material itself is engineered for this climate.

Interlock achieves UL 2218 Class 4, the highest impact rating available—the warranty even covers perforation from hailstones up to 1.5 inches. Chehalis's climate data doesn't flag hail as a frequent hazard, but spring wind gusts (routinely 102 km/h) can loft debris that dents softer materials. Aluminum's hardness resists denting better than asphalt or wood; dents are cosmetic, not structural, and the coating doesn't crack from impact the way brittle asphalt does. Many insurers offer discounts for Class 4 roofing because claim rates drop. Contact your agent with the UL 2218 rating and ESR-1790 code report—those documents often unlock savings.

Aluminum requires virtually none—no granule replacement, no algae treatment, no sealant reapplication. Asphalt shingles need inspection every 2–3 years and resealing every 5–7 years; wood shakes demand annual treatment to prevent rot and splitting in Chehalis's 1348 mm annual rainfall. Interlock's Alunar coating (warranted 30 years against chalking and fading per ASTM standards) stays stable through about 2811 annual sunshine hours and 42 cm of snow. Occasionally flush leaves from valleys; that's it. The CALGreen certification acknowledges the reduced-maintenance design. This adds up: over 50 years, you're avoiding dozens of service calls and material purchases.

Asphalt costs less upfront but requires replacement every 15–20 years. Interlock's Guardian warranty is a lifetime limited, non-prorated material warranty for the original owner, transferable for 50 years to the next owner—covering rust, rot, splitting, cracking, curling, and impact loss. Over 50 years, two asphalt roofs (roughly $8,000–12,000 each in labor and material) plus tear-off and landfill fees total $18,000+. Aluminum costs more initially but eliminates replacement and disposal cycles. Current regional promotion: no payments and no interest until Spring 2027 or 10% off installation. When you factor in zero maintenance in Chehalis's demanding climate (1348 mm rain, 42 cm snow, 45 freeze-thaw days), the gap narrows significantly—and metal wins if you stay 30+ years.

Yes—Interlock aluminum is roughly 95% recyclable at end-of-life, whereas asphalt shingles land in landfills for 300+ years. Chehalis homeowners installing metal avoid contributing to the tear-off-to-landfill cycle that happens every 15–20 years with asphalt. Aluminum manufactured since 1998 in Delta, BC, has been installed from coastal salt-air homes to an Antarctic research station, meaning the supply chain is proven and the material's durability means fewer replacement cycles. The Guardian warranty's 50-year transferable term encourages long-term stewardship—you're buying a roof that outlasts you, not a consumable. Recycling aluminum uses 5% of the energy required to smelt virgin ore, so at recycle time, the environmental payoff compounds.

Yes. Chehalis averages about 42 cm of snow, 1348 mm of rain, roughly 45 freeze–thaw days a year, with peak wind gusts near 102 km/h. Interlock® aluminum roofing is wind-rated to 193+ km/h (120 mph), UL 2218 Class 4 impact-rated and Class A fire-rated, and its four-way interlocking panels shed snow and resist ice dams and freeze–thaw cracking — all backed by a lifetime limited, transferable warranty.