I purchased a 12*8 self assemble polycarbonate greenhouse in February 2009. The assembly was quite difficult. When it was completed I was very pleased with the product. After two years small holes appeared in the top layer of the roof which did not cause a problem as it did not leak. The roofing panels slowly became more brittle and have now cracked and distorted and one has blown out despite the roof now being covered with a polythene sheet.
As the greenhouse cost over £500 I did expect the materials to last longer than four years before disintegrating. The company policy is that it has a one year guarantee and they now have no liability for a faulty product. There is a glowing write up in their brochure for polycarbonate sheeting but no mention of how long the material should last.
My advice is before buying make sure you get a guarantee on the materials or you may have money down the drain.
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