Anybody in the UK or Europe know of a cheap source of twinwall polycarbonate? 4mm, 6mm, or 10mm thickness is acceptable. I need 36m2 to cover the new greenhouse that I'm planning. So far the cheapest supply I have found comes to about £250.

Any other glazing options which are strong and durable would also be considered.

Thanks!

I know they make PMMA (polymethyl methacrylate), also called acrylic, twin wall panels in Europe. If you can get those I would recommend it as it doesn't yellow the way PC panels will over time.

Greg, the twin wall Polycarbonate panels that I have on my greenhouse are Teflon coated on one side. The coated side is placed toward the sun to prevent any degradation or yellowing. I have had PC glazing on my greenhouse for some years and, so far at least, I have seen no yellowing. Now that I read your post, I will keep an eye and see if I notice ay coloring.

I don't know much about polymethyl methacrylate. Does it allow more or less, or the same amount of light to pass into the greenhouse as polycarbonate? - Millet

Greg thanks for the tip I've never seen the acrylic twinwall sheets in the UK, I'll have a look for them.

The PMMA twin wall panels I'm familiar with are trade named Acrylite. Here are a few links:
http://greenhouse.acrylitebuildingproducts.com/content/product-advantages
http://www.acrylite.net/product/acrylite/en/products/multi-skin-sheet/alltop/pages/default.aspx
http://greenhouse.acrylitebuildingproducts.com/product/16mm-acrylite%C2%AE-high-impact-double-skinned-acrylic-sheet

Thanks Greg, I still can't find the acrylic twinwall sheets in the UK. I was thinking of using a clear reinforced tarpaulin. This would be much cheaper than twinwall polycarbonate but nowhere near as strong or secure. I even thought of using lots of clear plastic 2litre drinks bottles, but I can't even find those to buy in bulk.

Looks like I'll have to take a hit to the wallet and buy the twinwall polycarbonate, but at least it is the best greenhouse glazing available.