This is a public-interest archive. Personal data is pseudonymized and retained under GDPR Article 89.

Re: Polytunnel puzzle.

At 21:04 11/03/98 +0000, Eric Reinheimer wrote:
>Hello Ian,
>
>There are parts you can buy that are used in commercial poly 
>greenhouses to hold the plastic to the frame. I believe they are 
>metal channels with zig zag springs that secure the plastic into the 
>channels. I think they cost less than a dollar per foot.
>
>If you're interested, email me and I'll dig out the particulars.
>
>Eric
>
 Thanks Eric & others who responded to my question. I think I may have
misled people as to my requirements. I don't need to fix the the polythene
to the steel framework as such. The polythene will be stretched over the
metal hoops & secured along either side, probably by burying it in a trench.
At either end I have a timber framework, two horizontal beams (one at ground
level, & one at the appropriate height to form the top of a door frame.) Two
vertical beams form the two sides of the door frame. I believe that the most
appropriate means of fixing the poly at either end is to fold/pleat it &
then wrap the ends of the poly around battens, which are then nailed to the
timber framework. I guess what I really wanted to know was a). is there any
advice that could help me with what sounds to be a job that requires 10
pairs of hand ie folding, pleating, tightening, nailing etc, that could save
me some of the effort. For example is there any kind of clear setting
adhesive, with which I could glue the pleats in place, available? b)how
tight do I need to stretch the poly, to provide minimum wear & tear to the
poly? I've covered all of the frame with old carpet to lessen friction &
chose light colour carpet to minimise swings in temperature against the poly
as I believe that the cycle of hot/cold/hot/cold is likely to quicken the
deterioration of the poly.
c) any suggestions as to other means of dealing woith fixing the two ends.
ie alternatives to battens & nails
Basically what I want to end up with is a structure that is as durable as
possible, in a climate that varies between 40deg C days (like today, phew,
wilt) & 12 inches of snow (like we had a few months ago), and, fairly high
wind at any time of the year(we live on top of the hills). 

Just in case any of you are interested I did a breakdown of what it has cot
me so far (in Aussie dollars) :-

Polytunnel Greenhouse 4M wide x  6M long x approx 2.5M high.

Steel for framework (25 mm square galvanised tube  6.5M x 5
                                         7 x 10mm x 3mm flat bar (for
horizontal polysupport & bracing)
                                          Supplier bent the tube into
"arches" for $10 per length                                        $250
                                          scrap steel for brackets to attach
arches to pine posts                                       $nil
Timber   5 x 1.8M  treated pine posts (cut in half to form the base of the
structure on which the arches sit)
                                                                        Abou
t 450mm protrudes from the ground
$23
                  Timber framework at ends (salvaged when demolishing a
friends garage)                                              $nil
                   2 x 4M lengths of 100mm x 50mm treared pine (for base of
end framework                                                $33
                   3 "flyscreen" doors salvaged from the nature strips in
town on rubbish collection day                           $nil

Oxy/acetylene gases for welding
$ 40 (approx)

Polythene (ordered, not yet received)  11M x 9M (UV stabilised "greenhouse
standard")                                         $143   

This comes to a grand total of (tick,whirr) ..........$489 , which allowing
for a few nails, cut-off disks etc gives us $500 in round terms. I haven't
looked at prices of current  commercially made bolt together kits, but was
told by a neighbour that his 4 year old, & a quarter of the size of mine,
commercial polytunnel (or hoophouse for all you americans) cost him $700
new! Who can tell that I'm feeling rather smug & pleased with myself at the
moment :-))

regards
Ian
(from the Strzlecki Ranges, Australia).
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index