Topic: poly tunnel rotting.

[Good Gourd 2]

We bought a poly tunnel last year, it only cost around a £100, fitted it with hot spot tape and made it secure by digging down the sides.  That was last Feb/March. Now it is just dropping apart not just at the seams but all over. Has anyone else had this problem.  We thought it should have lasted at least 2 years.

[ACE]

Mine is over 8 years old and is still good apart from being a bit cloudy in places. I would get back on to the suppliers and have a shout. I would have thought even the thinnest plastic should last longer than one year. If you do have to recover it get some clear builders membrane.

[realfood]

At that price it sounds as if it may be one of the imported ones. Is the cover reinforced with green or white fibers like postage stamps? I have seen this material break up in just over a year.

[Vinlander]

It's all about UV and how much expensive UV absorbing substance has been included in the sheet.

They shouldn't sell you cheap polythene as part of a horticultural package and you have a strong case to say that what you were sold was unfit for purpose because they didn't use horticultural grade sheet. If you can make it stick then you get a full refund. Have a word with your local Trading Standards Officer.

Builders' stuff can be very good but varies wildly - I have used black damp-proof membrane as a sheet mulch for years (black always lasts longer than clear) and you can get some that lasts 10+years and some that's shattered into a thousand pieces 3 years later - and it's a nightmare to clear up afterwards.

I got some clear tarp reinforced with 8mm mesh that  took just 2 years to degrade to an open mesh - I'd only recommend it to someone who wants a lot of bird-mesh in 2015.

I'd be interested to know if the scaffold-screening stuff fares better??

Incidentally Polycarbonate is very tough and almost immune to UV (though it does go yellowish in 10 years or so). Expensive solution but you can really rely on it to last - on the other hand it blocks so much UV that you can't grow cacti under it (except epis that are happy halfway up in a jungle).

Cheers.

[RobinOfTheHood]

I've been using scaffold sheet - Monarflex - for the last 5 years after buying a 45x2m roll from a scaffold hire firm. The standard stuff - which I have - is crap. 2 years tops, I've recovered my greenhouse 3 times in 5 years and it's due again now. My roll has run out now so I'm unsure what to use next.

I am told that there is a UV resistant grade of scaffold sheet for long term use which a pal has used for years on end without issue but it's not cheap.

[Vinlander]

Thanks for confirmation Robin - I suspected scaffold sheet would be designed to be used, scuffed, torn, dirtied - and thrown away.

I'm still mildly annoyed that the tarp was no better - everyone re-uses tarp - even builders.

Wouldn't it be nice if they sold thin sheet made from Polycarb or PET? (the bottles last decades in the sun) - it would be worth buying good thick easy-to-handle stuff if you could be sure it would last 10 years.

I did try splitting twinwall polycarb - but it's tricky work and even though it would pay off over 15-20 years it's just so galling to do all that work undoing that complex (and often very useful) extrusion when all the buggers had to do to please me was squirt it out flat from the start...

You can get PVC sheet in the useful 180-300 micron range and it looks fantastic - but after my experiences with corrugated PVC... I wouldn't trust it to outlive a parsnip seed.

On the other hand the stuff seaside restaurants use as a 'rollerblind' windbreak seems to last years - even in the Canaries. Maybe it's UPVC? Would love to get my hands on some big offcuts!

Cheers.

PS. if anyone knows a good strong, simple and quick way to make a 'quilt' from the flat sides cut from PET bottles then please tell me - welding doesn't work because the stuff wrinkles like crazy when heated.