What Is a Polycarbonate Greenhouse?

"Greenhouse plastic" is a catch-all term, but the material covering most quality kits sold in Canada today is twin-wall polycarbonate — a rigid, UV-stabilized plastic sheet with a honeycomb air-gap structure between two layers. It's not the flimsy poly film you'd stretch over a hoop house, and it's not glass either. It's its own category, built to solve both of their weaknesses at once.

How it compares to glass

Glass looks classic, but it's heavy, expensive to ship, and it shatters — a real problem under hail or a falling branch. Polycarbonate is a fraction of the weight, flexes instead of cracking, and the twin-wall air gap gives it meaningfully better insulation than a single pane of glass. That insulation matters more in Canada than almost anywhere else greenhouses get sold.

How it compares to plastic film

Poly film greenhouses are cheap for a reason: the film degrades under UV exposure, tears in wind, and typically needs replacing every few years. UV-stabilized polycarbonate is rated for a decade or more outdoors without yellowing or going brittle, which is why we pair it with a frame that's warrantied for the same length of time.

What "4mm vs 6mm" actually means

Panel thickness affects both insulation and light transmission. 4mm panels let in slightly more light, which matters if you're growing light-hungry crops through a Canadian winter with already-short days. 6mm panels trade a small amount of light for extra insulation — a better call in colder regions or if you plan to heat the space through winter.

CE certification and UV protection

CE certification means the panels meet a recognized European standard for structural and material safety — not a marketing sticker, an actual third-party spec. UV stabilization is a coating baked into the panel itself, not sprayed on, so it doesn't wear off with washing or time.