Polycarbonate Greenhouses

Polycarbonate greenhouses replace traditional glass with twin-wall or triple-wall polycarbonate sheets, lighter, virtually unbreakable, and 30-40% better at heat retention than glass. The trade-off is light transmission: glass passes 90-92% of available light, polycarbonate 80-85%, which matters for high-light crops like tomatoes but rarely for general year-round growing. Aosom UK, Buy Sheds Direct and Cherry Lane Garden Centres between them cover £39-£2,999 across the range. Twin-wall 4mm polycarbonate is the household standard; 6mm twin-wall is the cold-frame-comfort upgrade; 10mm twin-wall and triple-wall 16mm push into commercial-grade. Frame matters as much as the glazing: aluminium frames last 25+ years and resist UK weather without painting; powder-coated steel rusts at corners after 5-7 years. Look for at least one roof vent (heat builds up fast in spring); auto-opening vents at £30-£60 each are worth the upgrade for unattended ventilation.