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dual wall (air gap) greenhouses - is it worth it?

Discussion in 'Greenhouse - Shade house.' started by yoodles, Apr 2, 2014.

  1. yoodles

    yoodles VIP Supporter

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    hi all, i live in the adelaide hills so i have the joy of 40+ in summer and down to -4 over night in winter.
    ive been looking at the possibility of doing a dual wall green house (small one for a dutch bucket setup) with say a 60 - 75mm gap in-between the outer and inner layer, has anyone else given this a shot, is it worth the extra experience or should i just go with dual wall poly carb sheeting?

    thanks
     
  2. JasonW

    JasonW Member

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    There is little difference in the R value between two layers of plastic and twin wall polycarbonate. The major difference is cost and function. We are in an area that can get a lot of hail in the summer months so we use twin wall polycarbonate for the roof and windows with another layer of plastic for the walls. Here is a good chart to show the R value you can get from different materials.
    http://www.littlegreenhouse.com/guide.shtml
     
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  3. Murray

    Murray Site Admin Staff Member

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    Depends where you live, but I would have one if I could afford it....for sure.
     
  4. yoodles

    yoodles VIP Supporter

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    im just going to build it myself, but being the poly carb is the most $$$$ part it does add to the price.
    but i figure if i set it up right i might run a 2nd AP system just for this green house and monitor it over winter with temps etc and possibly try at grow jades in the adelaide hills :)
     
  5. Pllatinum

    Pllatinum New Member

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    I built mine with double polyethylene. There's a 25mm gap between sheets. Is that something you're talking about?
     
  6. yoodles

    yoodles VIP Supporter

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    yes similar to that, do you have an air blower to inflate the layers or is it just gaped apart physically?
    does it make a difference?

    ive been thinking i might do a hybrid and put poly carb on the outside and plastic inside
     
  7. Pllatinum

    Pllatinum New Member

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    I don't have any sort of blower. I used 1" pvc pipe for the structure, and the poly wraps over the outside and then loops back and goes underneath to the inside. The 1" pipe keeps it spaced nicely. I'm finding that it stays insulated quite well (I'm in Minnesota, so that's a thing).
     
  8. KBiller

    KBiller New Member

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    Hello everyone first time poster and new to this aquaponic frenzy that is so easily to get addicted to. I myself discovered aquaponics just a few short months ago, actually Murray your short video on youtube got me hooked on the idea and my internet surfing has consisted of nothing more than anything aquaponics for about the last 4 months.

    Anyway getting back on subject I am currently in the construction phase of building my greenhouse and it will be a double walled poly greenhouse to house my future AP system.

    I'm in Virginia where the winter will be relatively light compared to other parts of the globe but it can occasionally get down to the single digits on a off night. I'm hoping to hold the heat in enough to run all year long efficiently.

    Ill be watching this post closely gaining any info I can for mine.
     

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  9. yoodles

    yoodles VIP Supporter

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    thats a nice sized greenhouse :)
     
  10. Bill C

    Bill C Member

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    Might not need a 2x walled GH in VA, as you said it does not get terribly cold for very long. I know that Nate Story uses a 2X walled GH but he is in Wyoming. Do you have an idea of how much total water will be in your system yet? The more water you have the more thermally stable the system will be.
     
  11. Granny's CSA

    Granny's CSA Member

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    Kbiller, we built our first greenhouse using cattle panels like you have. We really liked the setup and it worked great.
     
  12. yoodles

    yoodles VIP Supporter

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    KBiller, what have you used to attach the greenhouse film to the wood ?
    also did you build it in "pre fabricated" panels so to speak or built the frame in place and then attached the film?
    thanks
     
  13. miev77

    miev77 Member

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    Double layer with a blower really helps heating and cooling costs I have read it can reduce your electric bills by 40% so it is definitely worth it, and significantly cheaper in purchase price. Poly will stand up to snow loads with those cattle panels you have there no problem.
     

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