Help with putting up a 18ft Polytunnel

ballymac676

Hi I am looking for help from anyone who may have experience in putting up polytunnels. I purchased a few months ago from the North. Polytunnel is 18ft wide x 24ft long. The instructions are as clear as mud to me - I am hoping to get it up soon to have beds prepared for spring sowing. The plastic is not buried in ground but "clamped" between timber. thanks

dardevle

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not sure how much practical help i can give you, just wondering which company you purchased from?
instructions for polys do leave a lot to be desired and you may be better served by looking at examples on youtube,just look for tunnels constructed with base rails and it should give you a clue.....take things slowly, as a poorly installed tunnel will haunt you for as long as you use it.

if you have specific ?s just ask away.



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johngalway

One thing - that won't be of any help to you! - I keep reading how the plastic should be put on on a warm day, not a cool one. The theory being in warm weather the plastic is looser, so when you stretch it and the cooler weather comes it actually tightens up on the frame. But, if you put it on in cooler weather, when it warms up it'll loosen up and is, more prone to being removed by the wind.

I don't own one, I've never put one up, just recounting what I've read about them. Someone with experience of them will be able advise you better I'm sure.

ballymac676

Thanks for replies. Hope it is OK to say that I purchased from Morris Polytunnels. Because we have an exposed site I went for the thicker steel and hence the 18ft width. Was hoping to make a start this weekend but as usual it looks as though the weather is going to stop us. dardevle if it is OK I might come back to you for help when we get going here.

dardevle

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have nothing but good experience with morris tunnels (apart from the instructions),

at this point in time getting the layout for the anchor posts correct is the most important job and is pretty straightforward, just involves a lot of long measuring..... 4 corner positions first, then the location of the inner hoops from these, when you have these positions fixed with temporary stakes you can go ahead and excavate these positions in prep for concrete,take as much time as you need at this point because if the footprint of the poly is off, it will be translated into the dome itself further along.



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Roselm

Are you intending on burying the polythene? I would have thought that if it's just clamped between wooden boards (which aren't attached to anything) that the whole lot will lift off the frame when it gets windy?

dardevle

hi roselm
the plastic is sandwiched between 2 base rail timbers...usually a larger 4" x2" and a smaller batten type, the larger timber is in turn u-clamped to the hoop support legs(anchor posts) which are concreted into the ground, makes for a very sturdy and also very tidy tunnel when done correctly...also has the benefit of being somewhat adjustable if the plastic is clad on a cooler day, when it warms up and expands the u- clamps can be loosened and the timber readjusted downward to remove slack from the plastic.




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Roselm

dardevle wrote: »

hi roselm
the plastic is sandwiched between 2 base rail timbers...usually a larger 4" x2" and a smaller batten type, the larger timber is in turn u-clamped to the hoop support legs(anchor posts) which are concreted into the ground, makes for a very sturdy and also very tidy tunnel when done correctly...also has the benefit of being somewhat adjustable if the plastic is clad on a cooler day, when it warms up and expands the u- clamps can be loosened and the timber readjusted downward to remove slack from the plastic.




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Ah, thanks Dardevle. I hadn't heard of this way of doing things. Have only seen tunnels with the polythene buried

redser7

As you haven't started yet, buy 'The Polytunnel Handbook'. It has detailed instructions on erection. As mentioned, the most important thing for you is to get the foundation tubes located exactly square and in line. You use pythogoras's theorem to do that, otherwise known as the 3,4,5 rule. Google it and read up. Ask questions stage by stage or phone the seller if you get stuck. After sales support seems to be a necesity with a lot of tunnels.

ballymac676

Hi thanks again for replies. We have measured out the site using pythogoras's theorem. I am probably wrong but like most people unfamiliar with items I think I am some parts missing. Will be ring John (Moris) soon to go through the parts and this will hopefully help me understand the procedure a bit better. Will go to the library tomorrow and look up recommended book.