Cold Makes Materials Brittle

Plexiglass becomes significantly more rigid in cold temperatures and loses its ability to flex. Instead of bending under load, it can crack under snow weight, ice expansion or even minor impacts. Polycarbonate is stronger, but over time freeze-thaw cycles and constant exposure still lead to fatigue and reduced durability.

Failures are rarely immediate. Materials weaken gradually, then one cold night or additional load can cause sudden cracking.

Snow Load Is Heavier Than Expected

Wet Canadian snow adds significant weight very quickly. Clear plastic panels tend to flex and bow under that load, especially if the structure isn’t overbuilt.

Unlike metal roofing, snow does not shed easily from these surfaces. It sits, builds up and transfers stress directly into the panels and connection points.

Thermal Expansion Causes Movement

Plastic expands and contracts much more than aluminum or glass. In Canadian conditions, where temperatures swing from deep cold to summer heat, this creates constant movement.

Over time this leads to loosening at fasteners, small gaps, warping and eventually cracking around stress points.

UV Exposure and Aging

Over time, UV exposure causes panels to yellow, lose clarity and develop micro-cracks. This not only affects appearance but also gradually reduces structural strength.

Condensation and Ice Issues

These roofs tend to trap moisture, leading to condensation buildup. In winter, this can freeze and create ice layers, affecting both comfort and usability.

Often the Weakest Part of the Build

Even with a solid aluminum frame and well-built enclosure, a plastic roof often becomes the weakest link. It may start strong, but over time it tends to show wear sooner than the rest of the structure.

What We Recommend Instead of Polycarbonate Roofs

For better year-round durability, weather protection, and long-term performance, we typically recommend stronger porch enclosure roof systems that are better suited for Canadian conditions.