Which is better for a greenhouse roof?

The polycarbonate. It is clear, so plants get daylight, and the UV coating keeps it from yellowing. Steel blocks all light.

Galvanized steel typically outlasts polycarbonate, which can become brittle and crack after years of sun and hail. The polycarbonate's UV coating slows yellowing but does not make it permanent.

Is the polycarbonate worth it over steel?

Only if you need light through the roof. For an opaque shed or fence, the Imperial steel is the sturdier, fire-safe choice at $21.83 at Home Depot as of November 6, 2026.

Can I put the polycarbonate over an existing metal roof?

Yes. Its corrugated profile matches standard 26.5 in corrugated metal, so it works as a skylight strip. Plan 24 in of effective coverage per panel with one-rib overlap.

Does the Imperial panel need painting?

No. The mill galvanized finish stands up to weather on its own, but you can paint it for a different look. Seal cut edges to slow rust.

How much area does one Imperial panel cover?

28.7 sq ft per 6 ft by 2.15 ft panel. The polycarbonate covers about 24 in by the panel length, so a 12 ft panel covers roughly 24 sq ft.

Clear Corrugated Polycarbonate Roofing Panels vs Imperial Corrugated Roof & Wall Panels

Buy the polycarbonate panels if you want light through the roof, such as a greenhouse, skylight strip or covered patio. Buy the Imperial steel panels if you want an opaque, fireproof, rot-proof roof or wall skin that can be painted. The polycarbonate is cheaper at the entry price, $15.00 at panelprestigeoutdoors.com as of November 6, 2026, versus $21.83 at Home Depot for the Imperial panel as of the same date, but the polycarbonate is local pickup only in Lake Stevens, WA, and the Imperial panel covers 28.7 sq ft per 6 ft sheet.

Today the Clear Corrugated Polycarbonate Roofing Panels costs $6.83 less at its best price.

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