greenhouse glass vs polycarbonate

[Nik]

Just had a disaster at the plot. My half built greenhouse got picked up by the storm and dumped a few feet away. I've managed to save the frame bit I've lost a lot of glass. Replacement glass isn't cheap and as its quite an exposed spot I fear it may happen again. Replacing the lost panels with polycarbonate will be a lot cheaper and easier, but what is the disadvantage? What advantages does glass have over plastic apart from looking a bit nicer?

[Kristen]

Polycarbonate tends to blow out in a wind (the wind travelling over the structure creates negative pressure, same as air going over an airplane wing, which then provides list) and because Polycarbonate can "bow" it flexes, become too narrow in its bowed shape and thus pops out.

Can perhaps be "fixed" by silicon'ing them in.

My preference is glass, once its all in place and the greenhouse anchored down it shouldn't come out at all.

No experience of polycarbonate but does it deteriorate (light transmission?) with time, or become brittle?

It has other benefits - kids chucking stones / footballs / failing to make a crucial turn on a bicycle!!

[Thelma Sanders]

Once it's fixed down a greenhouse shouldn't blow away.
The weight of glass usually helps them stay put

If you go for plastic then silicone it in, as Kristen says, just be aware that the polycarb will discolour eventually, whereas glass doesn't.

[Greenleaves]

I have one of each and for me glass wins every time, but thats just personal choice. The pc one discolours quickly and is a faff reinforcing the panels but is easy to move.

[Potstubsdustbins]

Be aware if you use polycarbonate you will have to fasten it down very securely or it will become a kite.

It weighs very little my son and I carried my 6 x 8 into position fully glazed with no problem what so ever, it needed two of us to prevent the frame twisting not to carry the weight.

I secured my glazing with a good quality silicone sealant designed to bond metal and plastic in 6/7 years never lost a pane.

If you go the polycarbonate route be careful to check which side is out (it tells you on the plastic cover), otherwise you will get discolouration, also the inside is not UV protected.

[fishpond]

Having had polycarbonate, horticultural glass, and now toughened glass.
I can say that even though tg is very expensive this g/house is not going anywhere, it is very heavy.

[solway cropper]

How long do you intend to keep the greenhouse?

My big lean-to was erected about 30 years ago, before we moved here. All the glass is still crystal clear but a few panes that have been replaced by plastic are now varying shades of yellow-brown.

Call me old-fashioned but glass just seems more 'natural' for a greenhouse.

[polc1410]

I had a polycarb in a windy site. Needed the panes silicones in plus extra clips and some Louvre vents like you get on a toilet extractor fan to stop it from sucking the pains out.

Instead in January some monstrous winds too the door off then rocked it back and forth

Eventually the aluminium frame failed on a couple of braces and the structure failed and took the wooden base frame with it...

[rary]

I would go with P.C. I have lost 3 glasshouses to high winds and they were well secured, it just needs something to hit the glass and smash it for the wind to get in, I was picking up shards of glass for years, if you use P.C. as Potty said use good quality silicon sealant and if on a windy site strapping bolted through the frame.

[Kristen]

ON a windy site I would put a windbreak around a greenhouse - hedge or similar, but fencing if necessary. Not so close as to cast a shadow though. Apart from wind damage it also makes a huge difference to heat loss not having wind, even gentle breeze, continuous flowing over the glass. Even if not heating the greenhouse that can make a significant difference in Spring time.