Many customers come to us for polycarbonate sheet replacements. They complain that their old sheets have yellowed, aged severely or even cracked. Some failed only two to three years after installation, others three to four years. Customers are confused: “I thought polycarbonate sheets can last ten years. How could they become unusable within just a few years? We’ve lost confidence in polycarbonate sheets.”
What leads to such problems? We analyze the key causes below. You may refer to our previous article How to Distinguish High-Quality Polycarbonate Sheets for sheet selection guidance.
- The primary cause is counterfeit polycarbonate sheets. These products fail to meet the claimed thickness and weight standards, are manufactured with recycled materials, and lack a UV-protective coating. Such sheets are unreliable for outdoor use.
- Incorrect installation orientation. Polycarbonate sheets have two distinct sides. The side with printed text on the protective film must face outdoors. This side is coated with UV protection to resist ageing.
- Poor-quality silicone sealant. Sealants are classified as acidic or neutral. Only neutral silicone sealant should be used with polycarbonate sheets. Acidic glass sealants should generally be avoided.
- Improper installation. Construction quality greatly affects canopy service life. Professional installation needs to consider ventilation and waterproofing of panel holes, prevent sheet crushing during screw fastening, adopt dedicated waterproof screws, and avoid overly tight bending radii.
As of May 10, 2024, Has completed the 10,000-hour anti-ageing test. Light transmittance remained at 70% after the test.
How long does one hour of xenon lamp accelerated weathering test equal in real outdoor exposure?
A commonly referenced benchmark: 500 test hours approximate one year of outdoor service, for reference only.
There is no universally recognized conversion formula between accelerated testing hours and real-world conditions. Annual ultraviolet radiation, temperature and humidity vary greatly across regions and years.
Without UV coating, polycarbonate sheets lose ultraviolet resistance. Appearance changes are barely visible within the first 1–2 years after installation, followed by accelerated ageing, embrittlement, cracking and perforation.
