Janet,
Some polycarbonate roofing sheet has uv filtration and reflective
qualities to cut down the amount of light, so watch which one you go for.
Another factor is cost, polycarb is more expensive than glass. Cutting to
size is easy as it can be cut with any decent saw. To fix, rather than
screwing, on the assumption that you have a wooden greenhouse, either use
glazing bars (from the same people that sell polycarb) or make some plastic
(or aluminium) clips with a single screw hole long enough to support the
sheet across the join (50mm x 20mm say). The sheets are incredibly light and
strong so won't require much support. Ensure that you seal both ends using
tape, otherwise you will find all sorts of insects getting into the
channels,

regards,

David


"Janet Tweedy" wrote in message
...
Just an idea to run past the experts but would it be at all possible to
screw sheets of that polycarbonate stuff on the inside of glass for
winter protection? If I drilled holes in the sheets and screwed them to
the wood structure would it be better than bubble wrap which is a swine
to re use and clean.

janet
--
Janet Tweedy
Dalmatian Telegraph
http://www.lancedal.demon.co.uk