What is Polycarbonate (Greenhouses)?
Polycarbonate is a lightweight, virtually shatterproof plastic glazing material used as an alternative to glass in many UK greenhouses. Twin-wall or multi-wall polycarbonate panels trap air between layers, giving better insulation than single-pane glass, and its impact resistance makes it a popular choice for gardens with children or in hail-prone areas.
Polycarbonate’s strength comes from its layered construction – typically twin-wall or multi-wall – creating air pockets that significantly reduce heat transfer. This makes it far more thermally efficient than standard glass, crucial for greenhouse performance. Polycarbonate panels come in varying thicknesses, often measured in millimeters (e.g., 4mm, 6mm, 12mm), with thicker panels offering greater insulation and impact resistance. The UV stability of polycarbonate is also critical; look for grades specifically designed for outdoor use with a high UV protection rating (typically 99% or higher) to prevent yellowing and maintain clarity over time. Importantly, polycarbonate isn’t indestructible; while highly resistant to impacts from hail and falling objects, it can be damaged by sustained heavy loads or sharp tools. Careful installation is also key – using appropriate fixings designed for polycarbonate and avoiding overtightening is essential to prevent cracking.
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FAQ
What does ‘UV protection’ rating on polycarbonate mean?
The UV protection rating, usually a percentage (e.g., 99%), indicates how much of the harmful ultraviolet light from the sun is blocked by the panel. A higher percentage means less degradation and yellowing of the material over time, significantly extending its lifespan.
How does polycarbonate compare to glass in terms of insulation?
Polycarbonate offers approximately 2-3 times better thermal insulation than standard single-pane glass. This is due to the air gaps within the multi-wall construction, dramatically reducing heat loss during winter and heat gain during summer.
What size are polycarbonate greenhouse panels typically available in?
Polycarbonate sheets usually come in standard lengths (e.g., 2m or 3m) and widths (e.g., 1.2m or 1.8m). You can often purchase smaller quantities to cut to your specific requirements, but larger rolls are generally more cost-effective for larger greenhouses.
What type of fixings should I use when attaching polycarbonate?
You must use polycarbonate-specific fixings, typically using self-tapping screws with a neoprene washer. Standard wood screws will damage the material and compromise its strength; ensure the washers are correctly positioned to prevent water ingress.
Is it okay to paint polycarbonate?
While possible, painting polycarbonate is generally not recommended as it can reduce UV protection and alter the surface properties, potentially leading to premature degradation. If you do choose to paint, use a specialist UV-resistant exterior paint specifically designed for plastics.
What’s the difference between twin-wall and multi-wall polycarbonate?
Twin-wall panels have two layers of polycarbonate with an air gap between them, offering good insulation. Multi-wall panels (often 4 or 6 walls) have multiple air gaps, providing superior thermal performance but are typically more expensive.
How thick should I choose polycarbonate for my greenhouse?
For most UK greenhouses, a 6mm to 12mm panel thickness is recommended. Thicker panels (12mm+) offer better insulation and impact resistance but also add to the cost; consider your climate and usage when selecting the appropriate thickness.
What happens if polycarbonate gets damaged?
Minor scratches can usually be removed with a polycarbonate cleaner and polishing pad, but larger cracks or breaks require replacement of the affected panel. Carefully assess the extent of the damage before attempting any repairs.
Can I use polycarbonate in areas with high winds?
Yes, polycarbonate is designed to withstand moderate wind loads, however, ensure your greenhouse frame and fixings are also robust enough for the prevailing conditions – consult a structural engineer if you’re unsure about load-bearing capabilities.
Is polycarbonate more expensive than glass initially?
Polycarbonate panels typically have a higher initial cost compared to standard glass. However, the superior insulation properties and longer lifespan of polycarbonate often result in reduced energy costs over time, making it a more economical choice in the long run.