Plastic greenhouses

Various forms of plastic sheet and film have replaced glass in many modern greenhouses. The most widely used material is polyethyfilm – which is low in cost, lightweight, easy to fit, comes in wide sheets, and has a high light transmittance. Unfortunately, it also has a very short life and this is why it is almost entirely limited to commercial use in poly-tunnels and other agricultural enterprises. The standard grades of polyethyfilm have a lifespan of around nine months.

Other plastic materials have been more successful for hobby greenhouses but are much more expensive, these include polyvinyl chloride films and sheets, polyvinyl fluoride films, polycarbonate sheets, and acrylic sheets. These are all prone to tearing or to popping out of seals though, so maintenance is quite high.

Fibreglass reinforced plastic (FRP) sheets are used widely for glazing and their main advantages are that they are lightweight and impact resistant, compared to glass. They have a fairly high light transmitting function, only slightly less than that of glass or polyethylene. These are becoming more popular but obviously they cost more than any of the other forms of plasticized greenhouse window.

Glazing materials must transmit the maximum of amount of sunlight to the plants while also holding heat gain or loss to a minimum. Rigid, double-walled acrylic and polycarbonate glazing panels are relatively high in cost but they offer good insulating properties. Studies are currently testing a liquid foam or lightweight, polystyrene foam beads between two layers of covering to use to winterize greenhouses but at present the most common route is to use bubble wrap!