DIY Polytunnel Guttering

[Duronal]

I was having a good think today on how to bind guttering to a polytunnel. I've read about people using lengths of guttering on posts next to the tunnel and then running polythene to the guttering and fixing with tape, i've also had a look at the ready made self-adhesive guttering but both designs require a vertical service and due to my tunnels semi circle shape I don't really think these are viable options.

So i've come up with a lightweight, elegant and super cheap solution. The plan is to reuse the excess polyplastic that i trimmed after trenching to create a plastic gutter which runs into a water butt.

I'll try and attatch a diagram later to fully show the set up but i'll see if i can explain in detail here.

you will need a length of plastic/poly cover as long as your tunnel and approx 1 meter wide.

2 bamboo canes
a small section of copper pipe 7" long.
String/cable ties


Take a strip of plastic (the length of your tunnel) and lay 2 bamboo canes (butt to butt) down one of the long sides - make sure that these are longer than the length of plastic . Next slide a piece of copper plumbing pipe over the end of each cane (i'm sure blue mdpe pipe would work too) to fix the canes together. Now fold the plastic all the way round the bean canes once and then pinch in just enough to create a tube, fix this with poly tape/staples/sow. You should now have a piece of plastic with the side profile of the letter 'P'.

The next part of the plan is to erect a pair of bean row canes at each end of the tunnel - these should look like the letter A without the cross piece, make sure that these are securely tied/fixed 15cm below the top as this is where our joined canes will rest. Push these into the ground so that they're stable. Don't forget to make sure that the side where you want water to drain has to be lower than the other end for water to drain.

Next up pop the plastic canes onto this frame and make sure that you have an excess of plastic to the tunnel, this should hang and naturally create a U shape.

Fix the side of closest to the tunnel with poly repair tape, i suggest that you only use a small square at first so that you can run a check to make sure that your poly gutter is working. once you're happy that you have the right direction of flow then seal the edge with larger strips of poly repair tape.

place a water butt at the end where water is to drain and you should now have your very own DIY lightweight poly-gutter installed.

you may want to run the end of the gutter into a down pipe with a bucket catcher on the top so that you can filter the water for debris.

I will be trying to set this up tomorrow, if anyone can think of any problems then please pick holes as much as you like.

Kind regards

D

[Alison]

One of the manufacturers now sell a kit for poly tunnels. Don't know what it's like though.

[penny]

Sounds good to me I will give it a go ive been wondering about gutter on my tunnel for ages thank you.

[Duronal]

i managed to complete this little project today. It took about 2 hours as i had to make some additions to the design. Firstly i used 3 canes bound together instead of 1 to create a more sturdy side pole. This stopped the natural flex of the cane which was causing complications with the rain water draining to the butt. I have also included a mid support; this has been made from some spare timber driven into the ground with a U shaped plumbing clip on top.

I have only done half the tunnel this time as this design is in its infancy.
NB. I placed a couple of weights inside the poly gutter to help keep the shape during bluster conditions (like today!).

All in all the design seems to be working, i've thrown buckets of water at it and it's still there. Rain is forecast for tomorrow so i will try to report my results.

The most likely failure will be that of the repair tape as i need to go over the sealed edge with a continuous line of tape to ensure a better seal between gutter and polythene.

Photos will arrive tomorrow.

D

[Duronal]

I'm back! The gutter has now been resealed and the photos are below! Rain is forecast for tomorrow so i'm hoping to get some good results.

Enjoy

D

[Duronal]

Now that we've had some rain i can report that my design has been a resounding success.

In theory the active surface area of the tunnel and gutter means that i get 22.3 litres of water for every (uniform) 1mm of rain. In turn this means that i should be able to fill my barrel if we have 1 cubic cm (10mm).

I have altered the design to prevent failure along the sidepole by strengthening how the plastic is attatched. I have used cable ties through the round the plastic, in order to stop the plastic from tearing when under stress I re-used the old squares of polytape to reinforce the plastic on each side of the hole.

Finally i added a barrel and gutter end to allow me to channel the water where i want it to go. To ensure i had a good connection between butt and barrel i used the top of a 500ml water bottle as a funnel (this fits very nicely into the drain pipe and access hole in the barrel.)

Because I have sunk my barrel i've also installed a cheap draw pump to allow me to pump the water into a watering can. (this may be replaced with a powered pump at some later stage)

All in all everything works and i'm using less water than i was!

Hopefully someone will find this useful.

D

[supermum]

Aren't you worried the weight of the water in the gutter will rip the whole thing off the original wall and damage that ?

[Duronal]

Not really no, the lateral load on the polythene itself is very small and the polythene is enormously strong - certainly two guys pulling both ways on the plastic can't tear it in two without creating a failure point (hole). - In addition to the natural strength of the cover the tape which holds the gutter to the cover creates a contact point that is 5-6inches wide by 10 foot long (600 square inches in total) and thus any weight is spread pretty evenly.

To sure up the design i have added the middle support, this should stop any sagging of the canes and therefore prevent any water sitting in still in the gutter. Without this support I’d be less confident, but then again the commercial systems stick onto the poly with no supports at all and survive just fine.

IMHO the biggest danger to this design is wind. If the side support cane comes unstuck from the supports then the whole thing could balloon up and potentially rip itself off the polythene. I don't think the adhesive on the poly repair tape would hold onto the polythene long enough for it any damage to be done to the cover but the resulting rogue cane that is effectively attached to a sail would be a minor worry!

Once you factor in the huge attachment area that uses the polythene’s natural strength and the fact that in most scenarios the water is running out of the gutter (minimal weight) at a steady pace then I’m pretty sure it'll stay in place without becoming a danger. This said I will be regularly checking on the gutter over the season to report on it's longevity.

Having checked the water level today the gutter is certainly working as the barrel is now 1/4 full.

Cheers

D

[Duronal]

My 44 gallon barrel is now full and the seal on the poly is holding

[Duronal]

The last update......DO NOT add any weight inside the bag of polythene in any kind of windy conditions as this will be flung far and wide. the potential for polythene damage in this instance is quite large. It is also vital that you make sure that the side pole is fixed, it shoudn't be allowed to move up or down, let the poly move but restict anything solid.

I have installed another blue barrel and also hooked up a hand pump to help water transfer. Apart from the intial teething problems the gutter is working very well and the seal is holding.

[Duronal]

This design worked extremely well for a full season, the tape needed replacing at the beginning of the next season as snow had proved too much for the adhesive. All in all this was a cheap and easy solution to a problem. For the cost of new tape every year i'd recommend this to any tunnel user. If You can elevate your barrels or install a pump to create a high cistern - you can use natural water pressure to water the whole of the tunnel. Either via drip tubes or internal reservoirs.

[Glutton4...]

Thanks for updating this thread! This very subject has been debated on here recently, so it is useful to hear of a system that works. Especially as I am planning to actually put my Tunnel up this year. Have you done both sides now?

[chris]

I did wonder where you went, Duronal - from reading your helpful posts this year I'm going to be sowing my own potato strain (hopefully!) with some isolated flowers and hand pollination.