On 18/09/2012 11:51, Granity wrote:
Martin Brown;968990 Wrote:
On 17/09/2012 22:39, someone wrote:-
"Martin Brown" wrote in
message ...-
On 17/09/2012 13:47, harry.yates wrote:-
Can I have suggestions for alternative materials to use
instead of glass
for my greenhouse?-

If you intend to heat it then twinwall polycarbonate is
pretty good.
-
This sounds good to me as an alternative to installing the
difficult inner bubblewrap every autumn, with duck tape that
doesn't stick that well.

But as it's quite permanent, do you know how it is for
letting light through, e.g. UV and whatever rays it is that
plants need?-

If you use the 1cm thick stuff intended for conservatories I didn't find

there was much bother with lack of light. The light inside is more
diffuse but that helps prevent plant scorch. You do have to put it right

side out though. UV stabiliser is only on one side and it will yellow
badly if put in the wrong way up. A friend did this!

It is also worth having a panel of this stuff or plywood prepped for
emergency winter repairs on a heated greenhouse. eg.

'what' (http://tinyurl.com/8lu84ge)

Not that it helped me much in the storm of Xmas '97.

Isn't there a problem with polycarbonate in that it flexes in strong
winds and can pop out of it's fastening clips?

The 6mm stuff will jump out of clips at the slightest provocation and
you can't use glass style clips on their own. You have to put glazing
bars along the inside and bolt the polycarbonate down onto it or use the
dedicated structural fixings that conservatories are made of.

The latter is a much more expensive proposition but more likely to be
completely waterproof.

--
Regards,
Martin Brown