Polycarbonate Greenhouses- Are they better than glass?
Many gardeners in Europe have been using greenhouse polycarbonate sheets rather than glass for years but British gardeners have really only started to see the light.
There are many myths about the limitations of polycarbonate but the reality is with good quality UV coatings it can offer distinct advantages over the traditional glass glazed greenhouse.
How many of you have witnessed a misdirected football or a confused pheasant hit and shatter a glass panel? It is surprisingly easy to break a greenhouse glass panel. My father had a slightly loose glass door panel on his aluminium greenhouse. Every time there were high winds or he shut the door carelessly it would fall out and shatter. He replaced it with a UV protected, polycarbonate 4 years ago and it’s still as good as new. In addition to this it is much safer particularily for the elderly or if young children are around.
Insulation is another factor to consider especially with some of the cold winters we have had over recent years. The U value represents the thermal insulation of a material . The lower it is the better as it shows the heat loss per sq metre. 4mm thick greenhouse glass has a U value of 6.0 W/M2K whereas 4mm clear multiwall polycarbonate has a U value of 3.8W/M2K. This means you should be able to save money by not having to have your greenhouse heater on for quite so long.
The weight of the polycarbonate is much lighter than the equivalent with glass . A 2’ x 4’ panel of glass weighs about 7.44 kg whereas the same size in 4mm multiwall polycarbonate weighs only 0.6 kg. This means your structure doesn’t need to be as bulky or costly. If you are worried about panels “blowing” out ensure you have a good base and invest in high quality galvanised W clips to hold the panels in place.
This all sounds great but are there any catches?
You may have heard that polycarbonate goes yellow or cloudy. If you buy a good quality branded polycarbonate such as Palram or Marlon it has a UV protective layer on the outside which stops the UV from discolouring the polycarbonate. These greenhouse glazing sheets will come with a 10 year guarantee to give you peace of mind.
What about mould or algae? You need to put aluminium tape over the cut edges of your polycarbonate to stop moisture getting in and algae spreading into it .
What about the light for your plants? 4mm glass has a light transmission of approximately 95% whereas 4mm multiwall polycarbonate is 82-88%. This is slightly lower but it does have the advantage that the layers in the polycarbonate will diffuse the light. This is good for many plants.
So as you can see polycarbonate has many advantages for the keen gardener. If you want to try it contact a reputable supplier that uses high quality branded polycarbonate.